1.簡介
Android中網絡請求一般使用Apache HTTP Client或者采用HttpURLConnect，但是直接使用這兩個類庫需要寫大量的代碼才能完成網絡post和get請求，而使用android-async-http這個庫可以大大的簡化操作，它是基于Apache’s HttpClient ，所有的請求都是獨立在UI主線程之外，通過回調方法處理請求結果，采用android Handler message 機制傳遞信息。
2.特性
(1)采用異步http請求，并通過匿名內部類處理回調結果
(2)http請求獨立在UI主線程之外
(3)采用線程池來處理并發請求
(4)采用RequestParams類創建GET/POST參數
(5)不需要第三方包即可支持Multipart file文件上傳
(6)大小只有25kb
(7)自動為各種移動電話處理連接斷開時請求重連
(8)超快的自動gzip響應解碼支持
(9)使用BinaryHttpResponseHandler類下載二進制文件(如圖片)
(10) 使用JsonHttpResponseHandler類可以自動將響應結果解析為json格式
(11)持久化cookie存儲，可以將cookie保存到你的應用程序的SharedPreferences中
3.使用方法
(1)到官網http://loopj.com/android-async-http/下載最新的android-async-http-1.4.4.jar，然后將此jar包添加進Android應用程序 libs文件夾
(2)通過import com.loopj.android.http.*;引入相關類
(3)創建異步請求
- AsyncHttpClient client = new AsyncHttpClient();
- client.get("http://www.google.com", new AsyncHttpResponseHandler() {
- @Override
- public void onSuccess(String response) {
- System.out.println(response);
- }
- });
4.建議使用靜態的Http Client對象
在下面這個例子，我們創建了靜態的http client對象，使其很容易連接到Twitter的API
- import com.loopj.android.http.*;
-
- public class TwitterRestClient {
- private static final String BASE_URL = "http://api.twitter.com/1/";
-
- private static AsyncHttpClient client = new AsyncHttpClient();
-
- public static void get(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
- client.get(getAbsoluteUrl(url), params, responseHandler);
- }
-
- public static void post(String url, RequestParams params, AsyncHttpResponseHandler responseHandler) {
- client.post(getAbsoluteUrl(url), params, responseHandler);
- }
-
- private static String getAbsoluteUrl(String relativeUrl) {
- return BASE_URL + relativeUrl;
- }
- }
然后我們可以很容易的在代碼中操作Twitter的API
- import org.json.*;
- import com.loopj.android.http.*;
-
- class TwitterRestClientUsage {
- public void getPublicTimeline() throws JSONException {
- TwitterRestClient.get("statuses/public_timeline.json", null, new JsonHttpResponseHandler() {
- @Override
- public void onSuccess(JSONArray timeline) {
- // Pull out the first event on the public timeline
- JSONObject firstEvent = timeline.get(0);
- String tweetText = firstEvent.getString("text");
-
- // Do something with the response
- System.out.println(tweetText);
- }
- });
- }
- }
5. AsyncHttpClient, RequestParams ,AsyncHttpResponseHandler三個類使用方法
(1)AsyncHttpClient
public class AsyncHttpClient extends java.lang.Object
該類通常用在android應用程序中創建異步GET, POST, PUT和DELETE HTTP請求，請求參數通過RequestParams實例創建，響應通過重寫匿名內部類 ResponseHandlerInterface的方法處理。
例子：
- AsyncHttpClient client = new AsyncHttpClient();
- client.get("http://www.google.com", new ResponseHandlerInterface() {
- @Override
- public void onSuccess(String response) {
- System.out.println(response);
- }
- });
(2)RequestParams
public class RequestParams extends java.lang.Object
用于創建AsyncHttpClient實例中的請求參數(包括字符串或者文件)的集合
例子：
- RequestParams params = new RequestParams();
- params.put("username", "james");
- params.put("password", "123456");
- params.put("email", "my@email.com");
- params.put("profile_picture", new File("pic.jpg")); // Upload a File
- params.put("profile_picture2", someInputStream); // Upload an InputStream
- params.put("profile_picture3", new ByteArrayInputStream(someBytes)); // Upload some bytes
-
- Map<String, String> map = new HashMap<String, String>();
- map.put("first_name", "James");
- map.put("last_name", "Smith");
- params.put("user", map); // url params: "user[first_name]=James&user[last_name]=Smith"
-
- Set<String> set = new HashSet<String>(); // unordered collection
- set.add("music");
- set.add("art");
- params.put("like", set); // url params: "like=music&like=art"
-
- List<String> list = new ArrayList<String>(); // Ordered collection
- list.add("Java");
- list.add("C");
- params.put("languages", list); // url params: "languages[]=Java&languages[]=C"
-
- String[] colors = { "blue", "yellow" }; // Ordered collection
- params.put("colors", colors); // url params: "colors[]=blue&colors[]=yellow"
-
- List<Map<String, String>> listOfMaps = new ArrayList<Map<String, String>>();
- Map<String, String> user1 = new HashMap<String, String>();
- user1.put("age", "30");
- user1.put("gender", "male");
- Map<String, String> user2 = new HashMap<String, String>();
- user2.put("age", "25");
- user2.put("gender", "female");
- listOfMaps.add(user1);
- listOfMaps.add(user2);
- params.put("users", listOfMaps); // url params: "users[][age]=30&users[][gender]=male&users[][age]=25&users[][gender]=female"
-
- AsyncHttpClient client = new AsyncHttpClient();
- client.post("http://myendpoint.com", params, responseHandler);
(3)public class AsyncHttpResponseHandler extends java.lang.Object implements ResponseHandlerInterface
用于攔截和處理由AsyncHttpClient創建的請求。在匿名類AsyncHttpResponseHandler中的重寫 onSuccess(int, org.apache.http.Header[], byte[])方法用于處理響應成功的請求。此外，你也可以重寫 onFailure(int, org.apache.http.Header[], byte[], Throwable), onStart(), onFinish(), onRetry() 和onProgress(int, int)方法
例子：
- AsyncHttpClient client = new AsyncHttpClient();
- client.get("http://www.google.com", new AsyncHttpResponseHandler() {
- @Override
- public void onStart() {
- // Initiated the request
- }
-
- @Override
- public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
- // Successfully got a response
- }
-
- @Override
- public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error)
- {
- // Response failed :(
- }
-
- @Override
- public void onRetry() {
- // Request was retried
- }
-
- @Override
- public void onProgress(int bytesWritten, int totalSize) {
- // Progress notification
- }
-
- @Override
- public void onFinish() {
- // Completed the request (either success or failure)
- }
- });
6.利用PersistentCookieStore持久化存儲cookie
PersistentCookieStore類用于實現Apache HttpClient的CookieStore接口，可以自動的將cookie保存到Android設備的SharedPreferences中，如果你打算使用cookie來管理驗證會話，這個非常有用，因為用戶可以保持登錄狀態，不管關閉還是重新打開你的app
(1)首先創建 AsyncHttpClient實例對象
- AsyncHttpClient myClient = new AsyncHttpClient();
(2)將客戶端的cookie保存到PersistentCookieStore實例對象,帶有activity或者應用程序context的構造方法
- PersistentCookieStore myCookieStore = new PersistentCookieStore(this);
- myClient.setCookieStore(myCookieStore);
(3)任何從服務器端獲取的cookie都會持久化存儲到myCookieStore中，添加一個cookie到存儲中，只需要構造一個新的cookie對象，并且調用addCookie方法
- BasicClientCookie newCookie = new BasicClientCookie("cookiesare", "awesome");
- newCookie.setVersion(1);
- newCookie.setDomain("mydomain.com");
- newCookie.setPath("/");
- myCookieStore.addCookie(newCookie);
7.利用RequestParams上傳文件
類RequestParams支持multipart file 文件上傳
(1)在RequestParams 對象中添加InputStream用于上傳
- InputStream myInputStream = blah;
- RequestParams params = new RequestParams();
- params.put("secret_passwords", myInputStream, "passwords.txt");
(2)添加文件對象用于上傳
- File myFile = new File("/path/to/file.png");
- RequestParams params = new RequestParams();
- try {
- params.put("profile_picture", myFile);
- } catch(FileNotFoundException e) {}
(3)添加字節數組用于上傳
- byte[] myByteArray = blah;
- RequestParams params = new RequestParams();
- params.put("soundtrack", new ByteArrayInputStream(myByteArray), "she-wolf.mp3");
8.用BinaryHttpResponseHandler下載二進制數據
- BinaryHttpResponseHandler用于獲取二進制數據如圖片和其他文件
- AsyncHttpClient client = new AsyncHttpClient();
- String[] allowedContentTypes = new String[] { "image/png", "image/jpeg" };
- client.get("http://example.com/file.png", new BinaryHttpResponseHandler(allowedContentTypes) {
- @Override
- public void onSuccess(byte[] fileData) {
- // Do something with the file
- }
- });
參考資料：
http://loopj.com/android-async-http/