Android 异步Http框架简介和实现原理

在前几篇文章中《Android 采用get方式提交数据到服务器》《Android 采用post方式提交数据到服务器》《Android 采用HttpClient提交数据到服务器》介绍了android的两种提交数据到服务器的方法

本文将介绍另外一种基于框架android-async-http的方法来实现

android-async-http是一个强大的网络请求库，这个网络请求库是基于Apache HttpClient库之上的一个异步网络请求处理库，网络处理均基于Android的非UI线程，通过回调方法处理请求结果。android-async-http是一个强大的第三方开源网络请求库

官网源码：https://github.com/loopj/android-async-http

官网教程：http://loopj.com/android-async-http/

新建项目，先到github上：https://github.com/loopj/android-async-http/tree/1.4.0

下载相应的zip文件，解压缩后将src中的com文件夹复制到项目的src目录

Android 异步Http框架简介和实现原理_第1张图片

下面使用框架android-async-http，代码如下：

package com.wuyudong.asynchttp;import java.net.URLEncoder;import com.loopj.android.http.AsyncHttpClient;import com.loopj.android.http.AsyncHttpResponseHandler;import android.os.Bundle;import android.app.Activity;import android.view.View;import android.widget.Toast;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }    public void click(View view) {        // 用户名密码提交到服务器        AsyncHttpClient client = new AsyncHttpClient();        String path = "http://169.254.168.71:8080/web/LoginServlet?username="                + URLEncoder.encode("wuyudong") + "&password="                + URLEncoder.encode("123");        client.get(path, new AsyncHttpResponseHandler() {            @Override            public void onSuccess(String content) {                // TODO Auto-generated method stub                super.onSuccess(content);                Toast.makeText(MainActivity.this, "请求成功！", 0).show();            }            @Override            public void onFailure(Throwable error, String content) {                // TODO Auto-generated method stub                super.onFailure(error, content);                Toast.makeText(MainActivity.this, "请求失败！", 0).show();            }        });    }}

可以看到代码量减少了很多

下面来实现一个精简版的异步框架

新建项目

AsyncHttpClient.java

package com.wuyudong.AsyncClient;import java.io.IOException;import java.io.InputStream;import org.apache.http.HttpResponse;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.methods.HttpGet;import org.apache.http.impl.client.DefaultHttpClient;import android.os.Message;public class AsyncHttpClient {    public void get(final String path, final MyHandler myHandler) {        new Thread() {            @Override            public void run() {                HttpClient client = new DefaultHttpClient();                HttpGet httpGet = new HttpGet(path);                try {                    HttpResponse response = client.execute(httpGet);                    InputStream is = response.getEntity().getContent();                    String content = StreamTools.readInputStream(is);                    // 执行成功                    Message msg = new Message();                    msg.what = 0;                    msg.obj = "请求成功";                    myHandler.sendMessage(msg);                } catch (Exception e) {                    e.printStackTrace();                    // 执行失败                    Message msg = new Message();                    msg.what = 1;                    msg.obj = "请求失败";                    myHandler.sendMessage(msg);                }            }        }.start();    }}

MainActivity.java

package com.wuyudong.AsyncClient;import java.net.URLEncoder;import android.os.Bundle;import android.app.Activity;import android.view.View;import android.widget.Toast;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }    public void click(View view) {        // 1、开启子线程 执行一个http请求，在后台执行 在子线程执行        // 2、 子线程执行完毕后通知ui界面        AsyncHttpClient client = new AsyncHttpClient();        String path = "http://169.254.168.71:8080/web/LoginServlet?username="                + URLEncoder.encode("wuyudong") + "&password="                + URLEncoder.encode("123");        client.get(path, new MyHandler() {            @Override            public void onFailure(String content) {                Toast.makeText(MainActivity.this, content, 1).show();                super.onFailure(content);            }            @Override            public void onSuccess(String content) {                Toast.makeText(MainActivity.this, content, 0).show();                super.onSuccess(content);            }        });    }}

MyHandler.java

package com.wuyudong.AsyncClient;import android.os.Handler;import android.os.Message;public class MyHandler extends Handler {    public void onFailure(String content) {    }    public void onSuccess(String content) {    }    @Override    public void handleMessage(Message msg) {        String content = (String) msg.obj;        switch (msg.what) {        case 0:            onSuccess(content);            break;        case 1:            onFailure(content);            break;        default:            break;        }        super.handleMessage(msg);    }}

StreamTools.java

package com.wuyudong.AsyncClient;import java.io.ByteArrayOutputStream;import java.io.InputStream;public class StreamTools {    /**     * 把输入流的内容转化成字符串     *      * @param is     * @return     */    public static String readInputStream(InputStream is) {        try {            ByteArrayOutputStream baos = new ByteArrayOutputStream();            int len = 0;            byte[] buffer = new byte[1024];            while ((len = is.read(buffer)) != -1) {                baos.write(buffer, 0, len);            }            is.close();            baos.close();            byte[] result = baos.toByteArray();            String str = new String(result);            // 试着解析result里面的字符串            if (str.contains("gb2312")) {                return new String(result, "gb2312");            } else if(str.contains("utf-8")){                return str;            } else {                return null;            }                        //return new String(result, "gb2312");        } catch (Exception e) {            e.printStackTrace();            return null;        }    }}

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