Android Asynchronous Http Client-Android异步网络请求客户端接口

1.简介

Android中网络请求一般使用Apache HTTP Client或者采用HttpURLConnect，但是直接使用这两个类库需要写大量的代码才能完成网络post和get请求，而使用android-async-http这个库可以大大的简化操作，它是基于Apache’s HttpClient ，所有的请求都是独立在UI主线程之外，通过回调方法处理请求结果，采用android
Handler message 机制传递信息。

2.特性

(1)采用异步http请求，并通过匿名内部类处理回调结果

(2)http请求独立在UI主线程之外

(3)采用线程池来处理并发请求

(4)采用RequestParams类创建GET/POST参数

(5)不需要第三方包即可支持Multipart file文件上传

(6)大小只有25kb

(7)自动为各种移动电话处理连接断开时请求重连

(8)超快的自动gzip响应解码支持

(9)使用BinaryHttpResponseHandler类下载二进制文件(如图片)

(10) 使用JsonHttpResponseHandler类可以自动将响应结果解析为json格式

(11)持久化cookie存储，可以将cookie保存到你的应用程序的SharedPreferences中

3.使用方法

(1)到官网http://loopj.com/android-async-http/下载最新的android-async-http-1.4.4.jar，然后将此jar包添加进Android应用程序
libs文件夹

(2)通过import com.loopj.android.http.*;引入相关类

(3)创建异步请求

[java] view
plaincopy

AsyncHttpClient client = new AsyncHttpClient();

client.get("http://www.google.com", new AsyncHttpResponseHandler() {

@Override

public void onSuccess(String response) {

System.out.println(response);

}

});

4.建议使用静态的Http Client对象

在下面这个例子，我们创建了静态的http client对象，使其很容易连接到Twitter的API

[java] view
plaincopy

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;

}

}

然后我们可以很容易的在代码中操作Twitter的API

[java] view
plaincopy

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三个类使用方法

(1)AsyncHttpClient

public class AsyncHttpClient extends java.lang.Object

该类通常用在android应用程序中创建异步GET, POST, PUT和DELETE HTTP请求，请求参数通过RequestParams实例创建，响应通过重写匿名内部类 ResponseHandlerInterface的方法处理。

例子：

[java] view
plaincopy

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

用于创建AsyncHttpClient实例中的请求参数(包括字符串或者文件)的集合

例子：

[java] view
plaincopy

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

用于拦截和处理由AsyncHttpClient创建的请求。在匿名类AsyncHttpResponseHandler中的重写 onSuccess(int, org.apache.http.Header[], byte[])方法用于处理响应成功的请求。此外，你也可以重写 onFailure(int, org.apache.http.Header[],
byte[], Throwable), onStart(), onFinish(), onRetry() 和onProgress(int, int)方法

例子：

[java] view
plaincopy

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持久化存储cookie

PersistentCookieStore类用于实现Apache HttpClient的CookieStore接口，可以自动的将cookie保存到Android设备的SharedPreferences中，如果你打算使用cookie来管理验证会话，这个非常有用，因为用户可以保持登录状态，不管关闭还是重新打开你的app

(1)首先创建 AsyncHttpClient实例对象

[java] view
plaincopy

AsyncHttpClient myClient = new AsyncHttpClient();

(2)将客户端的cookie保存到PersistentCookieStore实例对象,带有activity或者应用程序context的构造方法

[java] view
plaincopy

PersistentCookieStore myCookieStore = new PersistentCookieStore(this);

myClient.setCookieStore(myCookieStore);

(3)任何从服务器端获取的cookie都会持久化存储到myCookieStore中，添加一个cookie到存储中，只需要构造一个新的cookie对象，并且调用addCookie方法

[java] view
plaincopy

BasicClientCookie newCookie = new BasicClientCookie("cookiesare", "awesome");

newCookie.setVersion(1);

newCookie.setDomain("mydomain.com");

newCookie.setPath("/");

myCookieStore.addCookie(newCookie);

7.利用RequestParams上传文件

类RequestParams支持multipart file 文件上传

(1)在RequestParams 对象中添加InputStream用于上传

[java] view
plaincopy

InputStream myInputStream = blah;

RequestParams params = new RequestParams();

params.put("secret_passwords", myInputStream, "passwords.txt");

(2)添加文件对象用于上传

[java] view
plaincopy

File myFile = new File("/path/to/file.png");

RequestParams params = new RequestParams();

try {

params.put("profile_picture", myFile);

} catch(FileNotFoundException e) {}

(3)添加字节数组用于上传

[java] view
plaincopy

byte[] myByteArray = blah;

RequestParams params = new RequestParams();

params.put("soundtrack", new ByteArrayInputStream(myByteArray), "she-wolf.mp3");

8.用BinaryHttpResponseHandler下载二进制数据

[java] view
plaincopy

BinaryHttpResponseHandler用于获取二进制数据如图片和其他文件

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

}

});

参考资料：http://loopj.com/android-async-http/