【lombok】lombok---帮你简化生成必要但臃肿的java代码工具【映射注解和lombok注解同时使用以及映射注解放在属性和get方法上的区别】-阿里云开发者社区

官方地址：https://projectlombok.org/

GitHub:https://github.com/rzwitserloot/lombok

指导说明文档：http://jnb.ociweb.com/jnb/jnbJan2010.html

===============================================================================================================

本来来说，lombok作为一个目前为止【2017-11-27】java并未将其作为标准来推广。还有很多人问使用它是否合适。

这里不做这种讨论！！！

===============================================================================================================

在使用之前，要明确一点，在开发过程中，一般情况下，仅使用@Data 即可满足生成entity类的大部分情况。

摘自指导文档：

Essentially, using @Data on a class is the same as annotating the class with a default @ToString and @EqualsAndHashCode as well as annotating each field with both @Getter and @Setter.

实质上，在一个类上使用@Data与用默认的@ToString和@EqualsAndHashCode注释这个类以及用@Getter和@Setter注释每个字段是一样的。

===============================================================================================================

使用起来：

一.安装lombok插件【idea使用为例】

二.项目引入lombok依赖

        <!--lombok-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

版本这里不给了，想使用最新版本的，可以自己加上。

三.lombok注解使用详解

在上面安装插件的时候，可以看到有很多的注解是被支持的：

官方的指导文档，时间久远。所以就找到下面的注解进行详解。

@Getter and @Setter

【属性级别，生成本属性的get和set方法】

AccessLevel.PROTECTED　　默认生成的方法为public，此属性可以设置生成方法的访问修饰符【非必须】

转化前：

package com.sxd.entity;


import lombok.AccessLevel;
import lombok.Getter;
import lombok.Setter;

public class Order {

   @Getter @Setter private String orderId;
   @Getter(AccessLevel.PROTECTED) @Setter  private User user;
   @Getter @Setter(AccessLevel.NONE) private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public void setOrderId(String orderId)
  {
    this.orderId = orderId;
  }
  
  public String getOrderId()
  {
    return this.orderId;
  }
  
  public void setUser(User user)
  {
    this.user = user;
  }
  
  protected User getUser()
  {
    return this.user;
  }
  
  public String getProductName()
  {
    return this.productName;
  }
}

View Code

=============================================================================

@ToString

【类级别，生成自定义的toString()方法】

exclude="｛字段1，字段2｝"　　生成的toString（）不包含哪些字段【非必须】

callSuper=true　　如果继承的有父类的话，可以设置callSuper 让其调用父类的toString()方法【非必须】

转化前：

package com.sxd.entity;


import lombok.ToString;

@ToString(exclude = {"orderId","user"},callSuper = false)
public class Order {

    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public String toString()
  {
    return "Order(productName=" + this.productName + ")";
  }
}

View Code

不使用上述属性值的话：

转化前：

package com.sxd.entity;


import lombok.ToString;

@ToString
public class Order {

    private String orderId;
    private User user;
    private String productName;


}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public String toString()
  {
    return "Order(orderId=" + this.orderId + ", user=" + this.user + ", productName=" + this.productName + ")";
  }
}

View Code

===================================================================================

@EqualsAndHashCode

【类级别，生成自定义的equals()方法和HashCode()方法】

exclude="｛字段1，字段2｝"　　生成的方法不包含哪些字段【非必须】

callSuper=true　　如果继承的有父类的话，可以设置callSuper 让其调用父类的方法【非必须】

转化前：

package com.sxd.entity;


import lombok.EqualsAndHashCode;

@EqualsAndHashCode(exclude = {"orderId","user"},callSuper = false)
public class Order {

    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $productName = this.productName;result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$productName = this.productName;Object other$productName = other.productName;return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
}

View Code

=====================================================================================

@NonNull

【属性级别，验证不能为null的注解，如果执行加了这个注解的setter方法时设置为Null，抛异常java.lang.NullPointerException】

转化前：

package com.sxd.entity;


import lombok.Getter;
import lombok.NonNull;
import lombok.Setter;

public class Order {

    private String orderId;
    private User user;
    @NonNull @Getter @Setter private String productName;

    public Order() {

    }

}

View Code

编译后：

package com.sxd.entity;

import lombok.NonNull;

public class Order
{
  private String orderId;
  private User user;
  @NonNull
  private String productName;
  
  public void setProductName(@NonNull String productName)
  {
    if (productName == null) {
      throw new NullPointerException("productName");
    }
    this.productName = productName;
  }
  
  @NonNull
  public String getProductName()
  {
    return this.productName;
  }
}

View Code

如果去执行setter方法并赋值Null,则报错：

注意报错行数：

===========================================================================================

@NoArgsConstructor

【类级别，生成无参构造方法】

　focus=true　　当类中有final字段没有被初始化时，编译器会报错，此时可用@NoArgsConstructor(force = true)，然后就会为没有初始化的final字段设置默认值 0 / false / null。对于具有约束的字段（例如@NonNull字段），不会生成检查或分配，因此请注意，正确初始化这些字段之前，这些约束无效。

转化前：

package com.sxd.entity;

import lombok.NoArgsConstructor;

@NoArgsConstructor(force = true)
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
}

View Code

=====================================================================================

@RequiredArgsConstructor

【类级别，生成有或无参的静态方法，用于获取本对象】

staticName = "自定义静态方法名"

转化前：

package com.sxd.entity;


import lombok.RequiredArgsConstructor;

@RequiredArgsConstructor(staticName = "build")
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

转化后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public static Order build()
  {
    return new Order();
  }
}

View Code

===============================================================================

@AllArgsConstructor

【类级别，生成全参构造方法】

转化前：

package com.sxd.entity;


import lombok.AllArgsConstructor;

@AllArgsConstructor
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

import java.beans.ConstructorProperties;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  @ConstructorProperties({"orderId", "user", "productName"})
  public Order(String orderId, User user, String productName)
  {
    this.orderId = orderId;this.user = user;this.productName = productName;
  }
}

View Code

================================================================================

@Data

【类级别，此注解为lombok中最常用注解】

【@Data 包含了@ToString，@EqualsAndHashCode，@Getter / @Setter和@RequiredArgsConstructor的功能】

staticConstructor="静态实例化方法名"

转化前：

package com.sxd.entity;


import lombok.Data;

@Data(staticConstructor = "build")
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public static Order build()
  {
    return new Order();
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $orderId = getOrderId();result = result * 59 + ($orderId == null ? 43 : $orderId.hashCode());Object $user = getUser();result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $productName = getProductName();result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$orderId = getOrderId();Object other$orderId = other.getOrderId();
    if (this$orderId == null ? other$orderId != null : !this$orderId.equals(other$orderId)) {
      return false;
    }
    Object this$user = getUser();Object other$user = other.getUser();
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$productName = getProductName();Object other$productName = other.getProductName();return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
  
  public void setOrderId(String orderId)
  {
    this.orderId = orderId;
  }
  
  public void setUser(User user)
  {
    this.user = user;
  }
  
  public void setProductName(String productName)
  {
    this.productName = productName;
  }
  
  public String toString()
  {
    return "Order(orderId=" + getOrderId() + ", user=" + getUser() + ", productName=" + getProductName() + ")";
  }
  
  public String getOrderId()
  {
    return this.orderId;
  }
  
  public User getUser()
  {
    return this.user;
  }
  
  public String getProductName()
  {
    return this.productName;
  }
}

View Code

@Accessors

【类级别，控制get、set方法】

fluent　　 boolean值，默认为false。此字段主要为控制生成的getter和setter方法前面是否带get/set；false带，true不带
chain 　　boolean值，默认false。如果设置为true，setter返回的是此对象，方便链式调用方法
prefix 　　设置前缀例如：@Accessors(prefix = "abc") private String abcAge 当生成get/set方法时，会把此前缀去掉

转化前：【注意三个属性设值以及生成】

package com.sxd.entity;


import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(fluent = false,chain = false,prefix = "aaa")
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public String toString()
  {
    return "Order(orderId=" + this.orderId + ", user=" + this.user + ", productName=" + this.productName + ")";
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $orderId = this.orderId;result = result * 59 + ($orderId == null ? 43 : $orderId.hashCode());Object $user = this.user;result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $productName = this.productName;result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$orderId = this.orderId;Object other$orderId = other.orderId;
    if (this$orderId == null ? other$orderId != null : !this$orderId.equals(other$orderId)) {
      return false;
    }
    Object this$user = this.user;Object other$user = other.user;
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$productName = this.productName;Object other$productName = other.productName;return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
}

View Code

===========================================================

转化前：【注意fluent】

package com.sxd.entity;


import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(fluent = true,chain = false)
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public void productName(String productName)
  {
    this.productName = productName;
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $orderId = orderId();result = result * 59 + ($orderId == null ? 43 : $orderId.hashCode());Object $user = user();result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $productName = productName();result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public void orderId(String orderId)
  {
    this.orderId = orderId;
  }
  
  public void user(User user)
  {
    this.user = user;
  }
  
  public String toString()
  {
    return "Order(orderId=" + orderId() + ", user=" + user() + ", productName=" + productName() + ")";
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$orderId = orderId();Object other$orderId = other.orderId();
    if (this$orderId == null ? other$orderId != null : !this$orderId.equals(other$orderId)) {
      return false;
    }
    Object this$user = user();Object other$user = other.user();
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$productName = productName();Object other$productName = other.productName();return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
  
  public String orderId()
  {
    return this.orderId;
  }
  
  public User user()
  {
    return this.user;
  }
  
  public String productName()
  {
    return this.productName;
  }
}

View Code

==============================================================================

转化前：【注意chain】

package com.sxd.entity;


import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(fluent = false,chain = true)
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public Order setProductName(String productName)
  {
    this.productName = productName;return this;
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $orderId = getOrderId();result = result * 59 + ($orderId == null ? 43 : $orderId.hashCode());Object $user = getUser();result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $productName = getProductName();result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public Order setOrderId(String orderId)
  {
    this.orderId = orderId;return this;
  }
  
  public Order setUser(User user)
  {
    this.user = user;return this;
  }
  
  public String toString()
  {
    return "Order(orderId=" + getOrderId() + ", user=" + getUser() + ", productName=" + getProductName() + ")";
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$orderId = getOrderId();Object other$orderId = other.getOrderId();
    if (this$orderId == null ? other$orderId != null : !this$orderId.equals(other$orderId)) {
      return false;
    }
    Object this$user = getUser();Object other$user = other.getUser();
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$productName = getProductName();Object other$productName = other.getProductName();return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
  
  public String getOrderId()
  {
    return this.orderId;
  }
  
  public User getUser()
  {
    return this.user;
  }
  
  public String getProductName()
  {
    return this.productName;
  }
}

View Code

===================================================================

转化前：【注意prefix】

package com.sxd.entity;


import lombok.Data;
import lombok.experimental.Accessors;

@Data
@Accessors(fluent = false,chain = true,prefix = "product")
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public String toString()
  {
    return "Order(orderId=" + this.orderId + ", user=" + this.user + ", productName=" + getName() + ")";
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $orderId = this.orderId;result = result * 59 + ($orderId == null ? 43 : $orderId.hashCode());Object $user = this.user;result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $productName = getName();result = result * 59 + ($productName == null ? 43 : $productName.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Order;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Order)) {
      return false;
    }
    Order other = (Order)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$orderId = this.orderId;Object other$orderId = other.orderId;
    if (this$orderId == null ? other$orderId != null : !this$orderId.equals(other$orderId)) {
      return false;
    }
    Object this$user = this.user;Object other$user = other.user;
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$productName = getName();Object other$productName = other.getName();return this$productName == null ? other$productName == null : this$productName.equals(other$productName);
  }
  
  public Order setName(String productName)
  {
    this.productName = productName;return this;
  }
  
  public String getName()
  {
    return this.productName;
  }
}

View Code

=========================================================================

@Cleanup

【代码级别，清理资源/关闭资源注解】

转化前：

public void testCleanUp() {
    try {
        @Cleanup ByteArrayOutputStream baos = new ByteArrayOutputStream();
        baos.write(new byte[] {'Y','e','s'});
        System.out.println(baos.toString());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

View Code

编译后：

public void testCleanUp() {
    try {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        try {
            baos.write(new byte[]{'Y', 'e', 's'});
            System.out.println(baos.toString());
        } finally {
            baos.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

View Code

=========================================================================

@Synchronized

【方法级别，同步/线程安全注解】

转化前：

private DateFormat format = new SimpleDateFormat("MM-dd-YYYY");

@Synchronized
public String synchronizedFormat(Date date) {
    return format.format(date);
}

View Code

编译后：

private final java.lang.Object $lock = new java.lang.Object[0];
private DateFormat format = new SimpleDateFormat("MM-dd-YYYY");

public String synchronizedFormat(Date date) {
    synchronized ($lock) {
        return format.format(date);
    }
}

View Code

=========================================================================

@Wither

【属性级别，提供了给final字段赋值的一种方法】

转化前：

import lombok.AccessLevel;
import lombok.NonNull;
import lombok.experimental.Wither;
public class WitherExample {
@Wither private final int age;
@Wither(AccessLevel.PROTECTED) @NonNull private final String name;

public WitherExample(String name, int age) {
  if (name == null) throw new NullPointerException();
  this.name = name;
  this.age = age;
}
}

View Code

编译后：

import lombok.NonNull;
public class WitherExample {
private final int age;
private @NonNull final String name;

public WitherExample(String name, int age) {
  if (name == null) throw new NullPointerException();
  this.name = name;
  this.age = age;
}

public WitherExample withAge(int age) {
  return this.age == age ? this : new WitherExample(age, name);
}

protected WitherExample withName(@NonNull String name) {
  if (name == null) throw new java.lang.NullPointerException("name");
  return this.name == name ? this : new WitherExample(age, name);
}
}

View Code

==================================================================================

@Builder

【类级别，为你的类生成复杂的构建器API】

转化前：

package com.sxd.entity;


import lombok.Builder;


@Builder
public class Order {
    private String orderId;
    private User user;
    private String productName;

}

View Code

编译后：

package com.sxd.entity;

import java.beans.ConstructorProperties;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public static class OrderBuilder
  {
    private String orderId;
    private User user;
    private String productName;
    
    public String toString()
    {
      return "Order.OrderBuilder(orderId=" + this.orderId + ", user=" + this.user + ", productName=" + this.productName + ")";
    }
    
    public Order build()
    {
      return new Order(this.orderId, this.user, this.productName);
    }
    
    public OrderBuilder productName(String productName)
    {
      this.productName = productName;return this;
    }
    
    public OrderBuilder user(User user)
    {
      this.user = user;return this;
    }
    
    public OrderBuilder orderId(String orderId)
    {
      this.orderId = orderId;return this;
    }
  }
  
  public static OrderBuilder builder()
  {
    return new OrderBuilder();
  }
  
  @ConstructorProperties({"orderId", "user", "productName"})
  Order(String orderId, User user, String productName)
  {
    this.orderId = orderId;this.user = user;this.productName = productName;
  }
}

View Code

==============================================================

@Delegate

【属性级别，同化所在属性的类型的方法到本类中】

转化前：【本属性类型为String】

package com.sxd.entity;


import lombok.experimental.Delegate;


public class Order {
    private String orderId;
    private User user;
    @Delegate private String productName;

}

View Code

编译后：

package com.sxd.entity;

import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.util.Locale;
import java.util.stream.IntStream;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  
  public IntStream codePoints()
  {
    return this.productName.codePoints();
  }
  
  public IntStream chars()
  {
    return this.productName.chars();
  }
  
  public String intern()
  {
    return this.productName.intern();
  }
  
  public char[] toCharArray()
  {
    return this.productName.toCharArray();
  }
  
  public String trim()
  {
    return this.productName.trim();
  }
  
  public String toUpperCase()
  {
    return this.productName.toUpperCase();
  }
  
  public String toUpperCase(Locale arg0)
  {
    return this.productName.toUpperCase(arg0);
  }
  
  public String toLowerCase()
  {
    return this.productName.toLowerCase();
  }
  
  public String toLowerCase(Locale arg0)
  {
    return this.productName.toLowerCase(arg0);
  }
  
  public String[] split(String arg0)
  {
    return this.productName.split(arg0);
  }
  
  public String[] split(String arg0, int arg1)
  {
    return this.productName.split(arg0, arg1);
  }
  
  public String replace(CharSequence arg0, CharSequence arg1)
  {
    return this.productName.replace(arg0, arg1);
  }
  
  public String replaceAll(String arg0, String arg1)
  {
    return this.productName.replaceAll(arg0, arg1);
  }
  
  public String replaceFirst(String arg0, String arg1)
  {
    return this.productName.replaceFirst(arg0, arg1);
  }
  
  public boolean contains(CharSequence arg0)
  {
    return this.productName.contains(arg0);
  }
  
  public boolean matches(String arg0)
  {
    return this.productName.matches(arg0);
  }
  
  public String replace(char arg0, char arg1)
  {
    return this.productName.replace(arg0, arg1);
  }
  
  public String concat(String arg0)
  {
    return this.productName.concat(arg0);
  }
  
  public CharSequence subSequence(int arg0, int arg1)
  {
    return this.productName.subSequence(arg0, arg1);
  }
  
  public String substring(int arg0, int arg1)
  {
    return this.productName.substring(arg0, arg1);
  }
  
  public String substring(int arg0)
  {
    return this.productName.substring(arg0);
  }
  
  public int lastIndexOf(String arg0, int arg1)
  {
    return this.productName.lastIndexOf(arg0, arg1);
  }
  
  public int lastIndexOf(String arg0)
  {
    return this.productName.lastIndexOf(arg0);
  }
  
  public int indexOf(String arg0, int arg1)
  {
    return this.productName.indexOf(arg0, arg1);
  }
  
  public int indexOf(String arg0)
  {
    return this.productName.indexOf(arg0);
  }
  
  public int lastIndexOf(int arg0, int arg1)
  {
    return this.productName.lastIndexOf(arg0, arg1);
  }
  
  public int lastIndexOf(int arg0)
  {
    return this.productName.lastIndexOf(arg0);
  }
  
  public int indexOf(int arg0, int arg1)
  {
    return this.productName.indexOf(arg0, arg1);
  }
  
  public int indexOf(int arg0)
  {
    return this.productName.indexOf(arg0);
  }
  
  public boolean endsWith(String arg0)
  {
    return this.productName.endsWith(arg0);
  }
  
  public boolean startsWith(String arg0)
  {
    return this.productName.startsWith(arg0);
  }
  
  public boolean startsWith(String arg0, int arg1)
  {
    return this.productName.startsWith(arg0, arg1);
  }
  
  public boolean regionMatches(boolean arg0, int arg1, String arg2, int arg3, int arg4)
  {
    return this.productName.regionMatches(arg0, arg1, arg2, arg3, arg4);
  }
  
  public boolean regionMatches(int arg0, String arg1, int arg2, int arg3)
  {
    return this.productName.regionMatches(arg0, arg1, arg2, arg3);
  }
  
  public int compareToIgnoreCase(String arg0)
  {
    return this.productName.compareToIgnoreCase(arg0);
  }
  
  public int compareTo(String arg0)
  {
    return this.productName.compareTo(arg0);
  }
  
  public boolean equalsIgnoreCase(String arg0)
  {
    return this.productName.equalsIgnoreCase(arg0);
  }
  
  public boolean contentEquals(CharSequence arg0)
  {
    return this.productName.contentEquals(arg0);
  }
  
  public boolean contentEquals(StringBuffer arg0)
  {
    return this.productName.contentEquals(arg0);
  }
  
  public byte[] getBytes()
  {
    return this.productName.getBytes();
  }
  
  public byte[] getBytes(Charset arg0)
  {
    return this.productName.getBytes(arg0);
  }
  
  public byte[] getBytes(String arg0)
    throws UnsupportedEncodingException
  {
    return this.productName.getBytes(arg0);
  }
  
  @Deprecated
  public void getBytes(int arg0, int arg1, byte[] arg2, int arg3)
  {
    this.productName.getBytes(arg0, arg1, arg2, arg3);
  }
  
  public void getChars(int arg0, int arg1, char[] arg2, int arg3)
  {
    this.productName.getChars(arg0, arg1, arg2, arg3);
  }
  
  public int offsetByCodePoints(int arg0, int arg1)
  {
    return this.productName.offsetByCodePoints(arg0, arg1);
  }
  
  public int codePointCount(int arg0, int arg1)
  {
    return this.productName.codePointCount(arg0, arg1);
  }
  
  public int codePointBefore(int arg0)
  {
    return this.productName.codePointBefore(arg0);
  }
  
  public int codePointAt(int arg0)
  {
    return this.productName.codePointAt(arg0);
  }
  
  public char charAt(int arg0)
  {
    return this.productName.charAt(arg0);
  }
  
  public boolean isEmpty()
  {
    return this.productName.isEmpty();
  }
  
  public int length()
  {
    return this.productName.length();
  }
}

View Code

==========================================================================

转化前：【所在属性类型为List】

package com.sxd.entity;


import lombok.experimental.Delegate;

import java.util.List;


public class Order {
    private String orderId;
    private User user;
    private String productName;
    @Delegate  private List<Integer> arrList;

}

View Code

编译后：

package com.sxd.entity;

import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Spliterator;
import java.util.function.UnaryOperator;

public class Order
{
  private String orderId;
  private User user;
  private String productName;
  private List<Integer> arrList;
  
  public Spliterator<Integer> spliterator()
  {
    return this.arrList.spliterator();
  }
  
  public List<Integer> subList(int arg0, int arg1)
  {
    return this.arrList.subList(arg0, arg1);
  }
  
  public ListIterator<Integer> listIterator(int arg0)
  {
    return this.arrList.listIterator(arg0);
  }
  
  public ListIterator<Integer> listIterator()
  {
    return this.arrList.listIterator();
  }
  
  public int lastIndexOf(Object arg0)
  {
    return this.arrList.lastIndexOf(arg0);
  }
  
  public int indexOf(Object arg0)
  {
    return this.arrList.indexOf(arg0);
  }
  
  public Integer remove(int arg0)
  {
    return (Integer)this.arrList.remove(arg0);
  }
  
  public void add(int arg0, Integer arg1)
  {
    this.arrList.add(arg0, arg1);
  }
  
  public Integer set(int arg0, Integer arg1)
  {
    return (Integer)this.arrList.set(arg0, arg1);
  }
  
  public Integer get(int arg0)
  {
    return (Integer)this.arrList.get(arg0);
  }
  
  public void clear()
  {
    this.arrList.clear();
  }
  
  public void sort(Comparator<? super Integer> arg0)
  {
    this.arrList.sort(arg0);
  }
  
  public void replaceAll(UnaryOperator<Integer> arg0)
  {
    this.arrList.replaceAll(arg0);
  }
  
  public boolean retainAll(Collection<?> arg0)
  {
    return this.arrList.retainAll(arg0);
  }
  
  public boolean removeAll(Collection<?> arg0)
  {
    return this.arrList.removeAll(arg0);
  }
  
  public boolean addAll(int arg0, Collection<? extends Integer> arg1)
  {
    return this.arrList.addAll(arg0, arg1);
  }
  
  public boolean addAll(Collection<? extends Integer> arg0)
  {
    return this.arrList.addAll(arg0);
  }
  
  public boolean containsAll(Collection<?> arg0)
  {
    return this.arrList.containsAll(arg0);
  }
  
  public boolean remove(Object arg0)
  {
    return this.arrList.remove(arg0);
  }
  
  public boolean add(Integer arg0)
  {
    return this.arrList.add(arg0);
  }
  
  public <T> T[] toArray(T[] arg0)
  {
    return this.arrList.toArray(arg0);
  }
  
  public Object[] toArray()
  {
    return this.arrList.toArray();
  }
  
  public Iterator<Integer> iterator()
  {
    return this.arrList.iterator();
  }
  
  public boolean contains(Object arg0)
  {
    return this.arrList.contains(arg0);
  }
  
  public boolean isEmpty()
  {
    return this.arrList.isEmpty();
  }
  
  public int size()
  {
    return this.arrList.size();
  }
}

View Code

============================================================================

@SneakyThrows

【异常处理注解，这里不做详细解释】

转化前：

@SneakyThrows
public void testSneakyThrows() {
    throw new IllegalAccessException();
}

View Code

编译后：

public void testSneakyThrows() {
    try {
        throw new IllegalAccessException();
    } catch (java.lang.Throwable $ex) {
        throw lombok.Lombok.sneakyThrow($ex);
    }
}

View Code

============================================================================

@_({注解1，注解2})或@_(注解) 配合onMethod=使用

【属性级别，用于将注解放在注解中使用】

转化前：

package com.sxd.entity;

import lombok.Getter;
import lombok.Setter;

import javax.persistence.Column;
import javax.persistence.Id;

public class Order {

    @Getter(onMethod = @_({@Column,@Id}))
    @Setter
    private String id;
}

View Code

编译后：

package com.sxd.entity;

import javax.persistence.Column;
import javax.persistence.Id;

public class Order
{
  private String id;
  
  @Column
  @Id
  public String getId()
  {
    return this.id;
  }
  
  public void setId(String id)
  {
    this.id = id;
  }
}

View Code

【注意：这个时而有用，时而报错，具体问题依旧找不到~~~~~~~~~~~~具体看附录2】

============================================================================================================

最后，如果使用了lombok的话，如何在实体类上声明实体对数据表的映射？

注意：@Column等注解是可以直接放在字段上而不用放在get方法上

例如：创建不同包下同名的实体类User.java

自己写get/set方法的User类如下：

package com.sxd.entity;



import org.hibernate.annotations.GenericGenerator;

import javax.persistence.*;

@Entity
@GenericGenerator(name = "uuid2", strategy = "org.hibernate.id.UUIDGenerator" )
public class User {
    private String id;
    private String username;
    private String password;
    private Integer age;

    @Id
    @GeneratedValue(generator = "uuid2")
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @Column(nullable = false)
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Column(nullable = false)
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Column(nullable = false)
    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public User() {

    }

    public User(String id, String username, String password, Integer age) {
        this.id = id;
        this.username = username;
        this.password = password;
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", age=" + age +
                '}';
    }
}

View Code

编译完是：

package com.sxd.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import org.hibernate.annotations.GenericGenerator;

@Entity
@GenericGenerator(name="uuid2", strategy="org.hibernate.id.UUIDGenerator")
public class User
{
  private String id;
  private String username;
  private String password;
  private Integer age;
  
  @Id
  @GeneratedValue(generator="uuid2")
  public String getId()
  {
    return this.id;
  }
  
  public void setId(String id)
  {
    this.id = id;
  }
  
  @Column(nullable=false)
  public String getUsername()
  {
    return this.username;
  }
  
  public void setUsername(String username)
  {
    this.username = username;
  }
  
  @Column(nullable=false)
  public String getPassword()
  {
    return this.password;
  }
  
  public void setPassword(String password)
  {
    this.password = password;
  }
  
  @Column(nullable=false)
  public Integer getAge()
  {
    return this.age;
  }
  
  public void setAge(Integer age)
  {
    this.age = age;
  }
  
  public User() {}
  
  public User(String id, String username, String password, Integer age)
  {
    this.id = id;
    this.username = username;
    this.password = password;
    this.age = age;
  }
  
  public String toString()
  {
    return "User{id='" + this.id + '\'' + ", username='" + this.username + '\'' + ", password='" + this.password + '\'' + ", age=" + this.age + '}';
  }
}

View Code

===================　　　　　　　　　　　　　　　　　　　　　==================================

使用lombok之后如下：

package com.sxd.controller;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.experimental.Accessors;
import org.hibernate.annotations.GenericGenerator;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
@GenericGenerator(name = "uuid2", strategy = "org.hibernate.id.UUIDGenerator" )
@Data(staticConstructor = "of")
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
public class User {
    @Id
    @GeneratedValue(generator = "uuid2")private String id;
    private String username;

    @Column(nullable = false)
    private String password;

    @Column(nullable = false)
    private Integer age;


}

View Code

编译完是：

package com.sxd.controller;

import java.beans.ConstructorProperties;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import org.hibernate.annotations.GenericGenerator;

@Entity
@GenericGenerator(name="uuid2", strategy="org.hibernate.id.UUIDGenerator")
public class User
{
  @Id
  @GeneratedValue(generator="uuid2")
  private String id;
  private String username;
  @Column(nullable=false)
  private String password;
  @Column(nullable=false)
  private Integer age;
  
  public User setAge(Integer age)
  {
    this.age = age;return this;
  }
  
  public String toString()
  {
    return "User(id=" + getId() + ", username=" + getUsername() + ", password=" + getPassword() + ", age=" + getAge() + ")";
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $id = getId();result = result * 59 + ($id == null ? 43 : $id.hashCode());Object $username = getUsername();result = result * 59 + ($username == null ? 43 : $username.hashCode());Object $password = getPassword();result = result * 59 + ($password == null ? 43 : $password.hashCode());Object $age = getAge();result = result * 59 + ($age == null ? 43 : $age.hashCode());return result;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof User;
  }
  
  public User setId(String id)
  {
    this.id = id;return this;
  }
  
  public User setUsername(String username)
  {
    this.username = username;return this;
  }
  
  public User setPassword(String password)
  {
    this.password = password;return this;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof User)) {
      return false;
    }
    User other = (User)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$id = getId();Object other$id = other.getId();
    if (this$id == null ? other$id != null : !this$id.equals(other$id)) {
      return false;
    }
    Object this$username = getUsername();Object other$username = other.getUsername();
    if (this$username == null ? other$username != null : !this$username.equals(other$username)) {
      return false;
    }
    Object this$password = getPassword();Object other$password = other.getPassword();
    if (this$password == null ? other$password != null : !this$password.equals(other$password)) {
      return false;
    }
    Object this$age = getAge();Object other$age = other.getAge();return this$age == null ? other$age == null : this$age.equals(other$age);
  }
  
  @ConstructorProperties({"id", "username", "password", "age"})
  public User(String id, String username, String password, Integer age)
  {
    this.id = id;this.username = username;this.password = password;this.age = age;
  }
  
  public String getId()
  {
    return this.id;
  }
  
  public String getUsername()
  {
    return this.username;
  }
  
  public String getPassword()
  {
    return this.password;
  }
  
  public Integer getAge()
  {
    return this.age;
  }
  
  public User() {}
}

View Code

有一个疑问，映射注解放在属性上和放在get方法上有什么区别？？？【看附录3】

===============================================================附录1：equals()方法和hashCode()方法的意义==========================================================

摘录：

1.hashcode是用来查找的，如果你学过数据结构就应该知道，在查找和排序这一章有  
例如内存中有这样的位置  
0  1  2  3  4  5  6  7    
而我有个类，这个类有个字段叫ID,我要把这个类存放在以上8个位置之一，如果不用hashcode而任意存放，那么当查找时就需要到这八个位置里挨个去找，或者用二分法一类的算法。  
但如果用hashcode那就会使效率提高很多。  
我们这个类中有个字段叫ID,那么我们就定义我们的hashcode为ID％8，然后把我们的类存放在取得得余数那个位置。比如我们的ID为9，9除8的余数为1，那么我们就把该类存在1这个位置，如果ID是13，求得的余数是5，那么我们就把该类放在5这个位置。这样，以后在查找该类时就可以通过ID除 8求余数直接找到存放的位置了。  
  
2.但是如果两个类有相同的hashcode怎么办那（我们假设上面的类的ID不是唯一的），例如9除以8和17除以8的余数都是1，那么这是不是合法的，
回答是：可以这样。那么如何判断呢？在这个时候就需要定义 equals了。  
也就是说，我们先通过 hashcode来判断两个类是否存放某个桶里，但这个桶里可能有很多类，那么我们就需要再通过 equals 来在这个桶里找到我们要的类。  
那么。重写了equals()，为什么还要重写hashCode()呢？  
想想，你要在一个桶里找东西，你必须先要找到这个桶啊，你不通过重写hashcode()来找到桶，光重写equals()有什么用啊

==============================================================附录2：@Getter()等lombok注解配合hibernate的映射注解怎么使用===========================================================

如果在项目中真的使用lombok的注解的话，映射注解应该如何处理呢？

寥寥无几的资料中有大概类似于如下的写法：

　　@Getter(onMethod = @_({@Id,@Column(name="id",nullable=false),@GeneratedValue(strategy= GenerationType.AUTO)}))
    @Setter
    private Integer id;

亲自试了一下，

如下：

报错如下：

其实在@Getter()注解接口中定义如下：

但是具体怎么去写，还没有研究出来。

【如有解决方法，不吝赐教！！】

所以，最终按照并列将注解写在属性上，而不是在@Getter（）注解中写@Column（）注解。

如下：

@Data(staticConstructor = "of")
@NoArgsConstructor
@AllArgsConstructor
@Accessors(chain = true)
@Entity
@GenericGenerator(name = "uuid2", strategy = "org.hibernate.id.UUIDGenerator" )
public class Member {


    @Id
    @GeneratedValue(generator = "uuid2")
    @Column(name = "memberId")
    private String memberId;

    @OneToOne(cascade = {CascadeType.MERGE,CascadeType.REFRESH},fetch = FetchType.EAGER)
    private User user;

    @Column(name="memberGrade",nullable = false)
    @NonNull
    private Integer memberGrade;
}

View Code

编译完成如下：

package com.sxd.entity;

import java.beans.ConstructorProperties;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToOne;
import lombok.NonNull;
import org.hibernate.annotations.GenericGenerator;

@Entity
@GenericGenerator(name="uuid2", strategy="org.hibernate.id.UUIDGenerator")
public class Member
{
  @Id
  @GeneratedValue(generator="uuid2")
  @Column(name="memberId")
  private String memberId;
  @OneToOne(cascade={javax.persistence.CascadeType.MERGE, javax.persistence.CascadeType.REFRESH}, fetch=FetchType.EAGER)
  private User user;
  @Column(name="memberGrade", nullable=false)
  @NonNull
  private Integer memberGrade;
  
  public String toString()
  {
    return "Member(memberId=" + getMemberId() + ", user=" + getUser() + ", memberGrade=" + getMemberGrade() + ")";
  }
  
  public int hashCode()
  {
    int PRIME = 59;int result = 1;Object $memberId = getMemberId();result = result * 59 + ($memberId == null ? 43 : $memberId.hashCode());Object $user = getUser();result = result * 59 + ($user == null ? 43 : $user.hashCode());Object $memberGrade = getMemberGrade();result = result * 59 + ($memberGrade == null ? 43 : $memberGrade.hashCode());return result;
  }
  
  public Member setMemberId(String memberId)
  {
    this.memberId = memberId;return this;
  }
  
  public Member setUser(User user)
  {
    this.user = user;return this;
  }
  
  public Member setMemberGrade(@NonNull Integer memberGrade)
  {
    if (memberGrade == null) {
      throw new NullPointerException("memberGrade");
    }
    this.memberGrade = memberGrade;return this;
  }
  
  protected boolean canEqual(Object other)
  {
    return other instanceof Member;
  }
  
  public boolean equals(Object o)
  {
    if (o == this) {
      return true;
    }
    if (!(o instanceof Member)) {
      return false;
    }
    Member other = (Member)o;
    if (!other.canEqual(this)) {
      return false;
    }
    Object this$memberId = getMemberId();Object other$memberId = other.getMemberId();
    if (this$memberId == null ? other$memberId != null : !this$memberId.equals(other$memberId)) {
      return false;
    }
    Object this$user = getUser();Object other$user = other.getUser();
    if (this$user == null ? other$user != null : !this$user.equals(other$user)) {
      return false;
    }
    Object this$memberGrade = getMemberGrade();Object other$memberGrade = other.getMemberGrade();return this$memberGrade == null ? other$memberGrade == null : this$memberGrade.equals(other$memberGrade);
  }
  
  @ConstructorProperties({"memberId", "user", "memberGrade"})
  public Member(String memberId, User user, @NonNull Integer memberGrade)
  {
    if (memberGrade == null) {
      throw new NullPointerException("memberGrade");
    }
    this.memberId = memberId;this.user = user;this.memberGrade = memberGrade;
  }
  
  public String getMemberId()
  {
    return this.memberId;
  }
  
  public User getUser()
  {
    return this.user;
  }
  
  @NonNull
  public Integer getMemberGrade()
  {
    return this.memberGrade;
  }
  
  public Member() {}
}

View Code

那么最后看附录3，了解最后一个问题，映射注解放在属性上和放在get方法上有什么区别？

=======================================================================附录3：映射注解放在属性上和放在get()方法上有什么区别======================================================================

摘录自：http://blog.csdn.net/most_rabbitfishes/article/details/70904949

对于属性字段和表的字段关系对应的注解属性的位置，一般我们采用以下两种方式:

第一种：

是把注解@Column(name ="xx")放在field上，一种是把注解放在get方法上一般放在field上看起来比较集中、清晰；

第二种：

是把注解@Column(name= "xx")放在get方法上，这种方式看起来比较散漫、不很清楚；

但是第一种方式这样做实际上破坏了java面向对象的封装性，原因是一般我们写javaBean，成员变量通常定义为private，目的就是不让别人来直接访问的私有属性，而我们把注解放在私有成员的变量上，就是默认hibernate可以直接访问我们的私有的成员变量，所以我们定义属性为private，就实际没有多大意义，至于hibernate为什么能访问，hibernate采用java的反射机制完全可以访问私有成员变量！所以应该放在get方法上，第二种方式这个时候就显得更加合理。

随即，我采用了附录2中实体用于hibernate自动生成数据表的表结构：

Hibernate自动帮我们建表:

如果我们采用注解的方式在我们的实体Bean上，又想通过扫描这些注解的Bean，通过Hibernate自动帮我们建表，那么你就会发现字段注解的位置不同甚至会影响到建表的结构，尤其是大字段、外键约束的生成效果。

如果采用第一种方式注解到私有字段上，这种帮我们建立表结构、约束条件和大字段Lob类型这些都是非常正常的，而通过第二种方式注解到get方法上，这种帮我们的建立的表大部分正常字段正常，而外键关联的和大字段就会出现问题.

虽然项目的开发我们不采用hibernate帮我们自动建表，通常我们还是要手动的建表，所以这一些是对于通过Hibernate帮我们自动建表要考虑的！而实际开发中，已注解在get方法上为多数！

结论：如上将注解建立在属性上，生成的表结构，约束条件，外键等都正常，所以，如果你要使用hibernate的生成策略，在你建立好实体之后自动去建立数据表的话，同时使用lombok的注解和映射注解都放在属性上是合适的！！！

【lombok】lombok---帮你简化生成必要但臃肿的java代码工具【映射注解和lombok注解同时使用以及映射注解放在属性和get方法上的区别】

@Getter and @Setter

=============================================================================

@ToString

===================================================================================

@EqualsAndHashCode

=====================================================================================

@NonNull

===========================================================================================

@NoArgsConstructor

=====================================================================================

@RequiredArgsConstructor

===============================================================================

@AllArgsConstructor

================================================================================

@Data

@Accessors

=========================================================================

@Cleanup

=========================================================================

@Synchronized

=========================================================================

@Wither

==================================================================================

@Builder

==============================================================

@Delegate

============================================================================

@SneakyThrows

============================================================================

@_({注解1，注解2})或@_(注解) 配合onMethod=使用

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【lombok】lombok---帮你简化生成必要但臃肿的java代码工具 【映射注解和lombok注解同时使用 以及 映射注解放在属性和get方法上的区别】

@Getter and @Setter

=============================================================================

@ToString

===================================================================================

@EqualsAndHashCode

=====================================================================================

@NonNull

===========================================================================================

@NoArgsConstructor

=====================================================================================

@RequiredArgsConstructor

===============================================================================

@AllArgsConstructor

================================================================================

@Data

@Accessors

=========================================================================

@Cleanup

=========================================================================

@Synchronized

=========================================================================

@Wither

==================================================================================

@Builder

==============================================================

@Delegate

============================================================================

@SneakyThrows

============================================================================

@_({注解1，注解2})或@_(注解) 配合onMethod=使用

热门文章

最新文章

相关课程

相关电子书

相关实验场景

【lombok】lombok---帮你简化生成必要但臃肿的java代码工具【映射注解和lombok注解同时使用以及映射注解放在属性和get方法上的区别】