Android Asynchronous-Http-Client断点续传

本文基于AsyncHttpClient实现了断点续传的功能（对于AsyncHttpClient导入及基本用法请参照我的上一篇文章）

1、先看下功能UI界面(下载：实现对文件的请求；取消：取消当前下载；删除：取消当前下载，删除下载的文件，将进度条重置)

注意：您应该验证，当你在下载过程中，取消了下载后，再次点击下载时是否从上次下载结束的地方开始请求。

2、UI布局文件

三、activity类文件

package com.analysys.asynchttpclientdemothree.activities;import android.media.MediaPlayer;
 import android.os.Handler;
 import android.os.Message;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ProgressBar;
 import android.widget.TextView;
 import android.widget.Toast;import com.analysys.asynchttpclientdemothree.R;
 import com.analysys.asynchttpclientdemothree.http_request_engine.HttpRequestEngine;import java.io.File;
 import java.io.IOException;public class MainActivity extends AppCompatActivity implements View.OnClickListener{private Button get;private Button cancel;private Button deleteButton;private TextView textView;private ProgressBar progressBar;//下面的地址是mp3文件地址，可能会失效；如果失效，您自己替换啊private String url = "http://wzg.free.fr/Joyeux-anniversaire.mp3";private MediaPlayer mediaPlayer;@Override
     protected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initView();}private void initView(){get = (Button)findViewById(R.id.getButtonId);get.setOnClickListener(this);cancel = (Button)findViewById(R.id.cancelButtonId);cancel.setOnClickListener(this);deleteButton = (Button)findViewById(R.id.deleteButtonId);deleteButton.setOnClickListener(this);textView = (TextView)findViewById(R.id.textViewId);progressBar = (ProgressBar)findViewById(R.id.progressBarId);}private void get(){File filesDir = this.getFilesDir();filesDir = new File(filesDir.getAbsoluteFile() + "/App");filesDir.mkdirs();HttpRequestEngine.get(url, new MainHandle(), filesDir.getAbsolutePath() + "/my.mp3");}private void cancel(){//先停止网络请求
         HttpRequestEngine.cancelGet();}private void delete(){//先停止网络请求
         HttpRequestEngine.cancelGet();//再处理本地UI
         progressBar.setProgress(0);if (mediaPlayer != null){mediaPlayer.stop();mediaPlayer.release();mediaPlayer = null;}//再删除文件
         File filesDir = MainActivity.this.getFilesDir();File file = new File(filesDir.getAbsoluteFile() + "/App/my.mp3");if (file.exists()){file.delete();}}@Override
     public void onClick(View v) {switch (v.getId()) {case R.id.getButtonId:get();break;case R.id.cancelButtonId:cancel();break;case R.id.deleteButtonId:delete();break;}}public class MainHandle extends Handler{public void handleMessage(Message msg) {//处理下载进度的回调
             if (msg.what == HttpRequestEngine.progressNotificationId){progressBar.setProgress(msg.arg1);textView.setText(msg.arg1 + "%");}//处理下载完成的回调
             if (msg.what == HttpRequestEngine.successNotificationId){File filesDir = MainActivity.this.getFilesDir();File file = new File(filesDir.getAbsoluteFile() + "/App/my.mp3");if (file.exists()){Log.d("MQL", "大小: " + file.length());MainActivity.this.installMp3(file);}}//处理下载失败的回调
             if (msg.what == HttpRequestEngine.failureNotificationId){Toast toast = Toast.makeText(MainActivity.this, (String)msg.obj, Toast.LENGTH_LONG);toast.show();}}}//播放
     private void installMp3(File file) {	

	if(mediaPlayer!=null && mediaPlayer.isPlaying()){

		return;

	}mediaPlayer = new MediaPlayer();try {mediaPlayer.setDataSource(file.getAbsolutePath());mediaPlayer.prepare();mediaPlayer.start();} catch (Exception e) {e.printStackTrace();}}
 }
 

四、HttpRequestEngine文件（该文件实现了断点续传的功能，提供对外的请求接口、取消接口）

package com.analysys.asynchttpclientdemothree.http_request_engine;import android.os.Handler;
 import android.os.Message;
 import android.util.Log;
 import java.io.File;import com.loopj.android.http.*;
 import cz.msebera.android.httpclient.Header;
 import cz.msebera.android.httpclient.HttpResponse;/**
  * Created by MQL on 2016/9/27.
  * 功能：提供网络请求
  */
 public class HttpRequestEngine {private static AsyncHttpClient client = new AsyncHttpClient();private static RequestHandle getRequestHandle;  //使用它取消具体某个请求
     private static Handler mainHandler;             //回调通知
 
     private static String Tag = "MQL";private static String targetFilePath;           //目标文件保存路径
     private static long fromLength = 0;             //请求前，本地已有的字节大小
 
     public static final int progressNotificationId = 1000;public static final int successNotificationId = 1001;public static final int failureNotificationId = 1002;//不带参数的get请求
     public static void get(String url, Handler mainHandler,String targetFilePath ){//先取消当前活动的请求
         cancelGet();//记录Handler For Callback;记录目标文件保存路径
         HttpRequestEngine.mainHandler = mainHandler;HttpRequestEngine.targetFilePath = targetFilePath;//发送新的请求
         HttpRequestEngine.get(url, new FileAsyncHttpResponseHandler(new File(targetFilePath), true) {@Override
             public void onPreProcessResponse(ResponseHandlerInterface instance, HttpResponse response) {Log.d("MQL", "onPreProcessResponse");if (response.getStatusLine().getStatusCode() == 416){//416: request Range Not Satisfiable, 出现这种请求立即取消请求
 
                     if (HttpRequestEngine.mainHandler != null){Message msg1 = new Message();msg1.what = HttpRequestEngine.progressNotificationId;msg1.arg1 = 100;HttpRequestEngine.mainHandler.sendMessage(msg1);Message msg2 = new Message();msg2.what = HttpRequestEngine.successNotificationId;HttpRequestEngine.mainHandler.sendMessage(msg2);}cancelGet();}else if (response.getStatusLine().getStatusCode() == 403){//Forbidden
                     if (HttpRequestEngine.mainHandler != null){Message msg = new Message();msg.what = HttpRequestEngine.failureNotificationId;msg.obj = "Forbidden";HttpRequestEngine.mainHandler.sendMessage(msg);}cancelGet();}}public void onSuccess(int statusCode, Header[] headers, File file){Log.d("MQL", "onSuccess");if (statusCode == 206) {if (HttpRequestEngine.mainHandler != null){Message msg = new Message();msg.what = HttpRequestEngine.successNotificationId;HttpRequestEngine.mainHandler.sendMessage(msg);}}}public void onFailure(int statusCode, Header[] headers, Throwable throwable, File file){Log.d("MQL", "onFailure: " + throwable.toString());if (HttpRequestEngine.mainHandler != null){Message msg = new Message();msg.what = HttpRequestEngine.failureNotificationId;msg.obj = throwable.toString();HttpRequestEngine.mainHandler.sendMessage(msg);}}public void onProgress(long bytesWritten, long totalSize) {Log.d("MQL", "" + (bytesWritten + HttpRequestEngine.fromLength)  + ", " + (totalSize + HttpRequestEngine.fromLength));int progress = (int)((totalSize > 0) ? ((bytesWritten + HttpRequestEngine.fromLength) * 1.0 / (totalSize + HttpRequestEngine.fromLength)) * 100 : -1);if (HttpRequestEngine.mainHandler != null){Message msg = new Message();msg.what = HttpRequestEngine.progressNotificationId;msg.arg1 = progress;HttpRequestEngine.mainHandler.sendMessage(msg);}}} );}//不带参数的get请求
     private static void get(String url, AsyncHttpResponseHandler responseHandler) {//获取文件大小
         File file = new File(HttpRequestEngine.targetFilePath);HttpRequestEngine.fromLength = 0;if (file.exists()){HttpRequestEngine.fromLength = file.length();}//通过设置请求头，使请求可以断点处继续请求
         client.addHeader("Range", "bytes=" + HttpRequestEngine.fromLength + "-");HttpRequestEngine.getRequestHandle = client.get(url, responseHandler);}//取消不带参数的get请求
     public static void cancelGet(){if (HttpRequestEngine.getRequestHandle != null){HttpRequestEngine.getRequestHandle.cancel(true);HttpRequestEngine.getRequestHandle = null;}if (HttpRequestEngine.mainHandler != null){HttpRequestEngine.mainHandler = null;}}
 }