Volley - Android HTTP client
Part 1 - Quickstart
Were can I get it?
Download volley library and import it as a library project or make a jar file.
git clone https://android.googlesource.com/platform/frameworks/volley
Why Volley?
-
Simple
-
Powerful
-
Extendable
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Built-in memory cache
-
Built-in disk cache
How to use it?
Step 1 - Create request queue
RequestQueue requestQueue = Volley.newRequestQueue(context.getApplicationContext());
Step 2 - Create request
StringRequest request = new StringRequest( Request.Method.GET, url, listener, errorListener);
Step 3 - Create listeners
Response.Listener<String> listener = new Response.Listener<String>() {
@Override
public void onResponse(String response) {
L.d("Success Response: " + response.toString());
}};Response.ErrorListener errorListener = new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
if (error.networkResponse != null) {
L.d("Error Response code: " + error.networkResponse.statusCode);
}
}};
Step 4 - Add request to queue
requestQueue.add(request);
Request methods:
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Request.Method.GET
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Request.Method.POST
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Request.Method.PUT
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Request.Method.DELETE
Request types:
Every request listener returns appropriate type.
-
String
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Json Object
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Json Array
-
Bitmap
You can create your own type
Example of request which adds some cookie.
public class CookieRequest extends StringRequest {
private String mCookieValue;
public CookieRequest(String url, String cookieValue,
Response.Listener<String> listener,
Response.ErrorListener errorListener) {
super(Method.GET, url, listener, errorListener);
mCookieValue = cookieValue;
}
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
Map<String, String> map = new HashMap<String, String>();
map.put("Cookie", mCookieValue);
return map;
}}
How to pass post request parameters?
You need to override getParams() method.
StringRequest request = new StringRequest(
Request.Method.POST,
url,
listener,
errorListener) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> map = new HashMap<String, String>();
map.put("name", "Jon Doe");
map.put("age", "21");
return map;
}};
How to set request retry policy?
StringRequest request = new StringRequest( Request.Method.GET, url, listener, errorListener);request.setRetryPolicy( new DefaultRetryPolicy( DefaultRetryPolicy.DEFAULT_TIMEOUT_MS, // 2500 DefaultRetryPolicy.DEFAULT_MAX_RETRIES, // 1 DefaultRetryPolicy.DEFAULT_BACKOFF_MULT)); //1f
HTTP basic authorization
StringRequest request = new StringRequest(
Request.Method.GET,
url,
listener,
errorListener) {
@Override
public Map<String, String> getHeaders() throws AuthFailureError {
return createBasicAuthHeader("user", "passwd");
}};
Map<String, String> createBasicAuthHeader(String username, String password) {
Map<String, String> headerMap = new HashMap<String, String>();
String credentials = username + ":" + password;
String base64EncodedCredentials =
Base64.encodeToString(credentials.getBytes(), Base64.NO_WRAP);
headerMap.put("Authorization", "Basic " + base64EncodedCredentials);
return headerMap;}
How to cancel request?
StringRequest request1 = new StringRequest(...);request1.setTag("weather-screen"); // request tagStringRequest request2 = new StringRequest(...);request2.setTag("weather-screen"); // request tagrequestQueue.add(request1);requestQueue.add(request2);
To cancel request you just need to remember request tag and call cancelAll(...) method.
requestQueue.cancelAll("weather-screen"); // cancel all requests with "weather-screen" tag
SEE ALSO:
本文转自 h2appy 51CTO博客，原文链接：http://blog.51cto.com/h2appy/1661624，如需转载请自行联系原作者
