多线程下载文件

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="vertical"
 6     tools:context=".MainActivity" >
 7 
 8     <EditText
 9         android:id="@+id/et_path"
10         android:layout_width="fill_parent"
11         android:layout_height="wrap_content"
12         android:text="http://202.96.2.126/android/360.exe"
13         android:hint="请输入地址" />
14     
15      <ProgressBar
16         android:id="@+id/pb"
17         style="?android:attr/progressBarStyleHorizontal"
18         android:layout_width="fill_parent"
19         android:layout_height="wrap_content" />"
20      
21     <Button 
22         android:onClick="downLoad"
23         android:layout_width="wrap_content"
24         android:layout_height="wrap_content"
25         android:text="下载"
26         />
27 
28    
29 
30 </LinearLayout>

 <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

  1 package com.example.mymutildownload;
  2 
  3 import java.io.File;
  4 import java.io.FileInputStream;
  5 import java.io.InputStream;
  6 import java.io.RandomAccessFile;
  7 import java.net.HttpURLConnection;
  8 import java.net.URL;
  9 
 10 import android.os.Bundle;
 11 import android.app.Activity;
 12 import android.text.TextUtils;
 13 import android.view.Menu;
 14 import android.view.View;
 15 import android.widget.EditText;
 16 import android.widget.ProgressBar;
 17 import android.widget.Toast;
 18 
 19 public class MainActivity extends Activity {
 20 
 21     private EditText et_path;
 22     private ProgressBar pb;
 23     private static int threadCount=3;
 24     private static int liveThread = 3;
 25     private static int currentLength = 0;
 26     @Override
 27     protected void onCreate(Bundle savedInstanceState) {
 28         super.onCreate(savedInstanceState);
 29         setContentView(R.layout.activity_main);
 30         et_path = (EditText)findViewById(R.id.et_path);
 31         pb = (ProgressBar)findViewById(R.id.pb);
 32     }
 33 
 34 
 35     public void downLoad(View view){
 36         final String path = et_path.getText().toString().trim();
 37         if(TextUtils.isEmpty(path)){
 38             Toast.makeText(this, "路径不能为空", 0).show();
 39             return;
 40         }
 41         
 42         new Thread(){
 43             public void run(){
 44                 try {
 45                     URL url = new URL(path);
 46                     HttpURLConnection conn = (HttpURLConnection) url.openConnection();
 47                     conn.setReadTimeout(5000);
 48                     conn.setRequestMethod("GET");
 49                     int code = conn.getResponseCode();
 50                     if(code == 200){
 51                         int length = conn.getContentLength();
 52                         System.out.println("文件的长度:" + length);
 53                         //生成一个文件
 54                         RandomAccessFile raf = new RandomAccessFile("/sdcard/360.exe", "rwd");
 55                         raf.setLength(length);
 56                         raf.close();
 57                         
 58                         //设置进度条的长度
 59                         pb.setMax(length);
 60                         //文件大小
 61                         int blockSize = length / threadCount;
 62                         for(int threadId=1; threadId <= threadCount; threadId++){
 63                             //下载的起始位置
 64                             int startIndex = (threadId - 1) * blockSize;
 65                             //结束位置
 66                             int endIndex = threadId * blockSize - 1;    
 67                             if(threadId == threadCount){
 68                                 endIndex = length;
 69                             }        
 70                             System.out.println("线程" + threadId + "的起始位置为:" + startIndex + " 结束位置为:" + endIndex);
 71                             //启动线程
 72                             new DownloadThread(threadId, startIndex, endIndex, path).start();
 73                         }
 74                     }
 75                 } catch (Exception e) {
 76                     // TODO Auto-generated catch block
 77                     e.printStackTrace();
 78                     System.out.println("链接失败");
 79                 }
 80             };
 81         }.start();
 82     }
 83     
 84     
 85     public class DownloadThread extends Thread{
 86         private int threadId;
 87         private int startIndex;
 88         private int endIndex;
 89         private String path;
 90         public DownloadThread(int threadId, int startIndex, int endIndex,
 91                 String path) {
 92             this.threadId = threadId;
 93             this.startIndex = startIndex;
 94             this.endIndex = endIndex;
 95             this.path = path;
 96         }
 97         @Override
 98         public void run(){
 99             try {
100                 //判断文件是否存在
101                 File tmpFile = new File("/sdcard/" + threadId + ".txt");
102                 if(tmpFile.exists()){
103                     FileInputStream fis = new FileInputStream(tmpFile);
104                     byte[] buf = new byte[1024];
105                     fis.read(buf);
106                     String downedLen = new String(buf).trim();
107                     startIndex = Integer.parseInt(downedLen);
108                     fis.close();
109                 }
110                 
111                 System.out.println("线程" + threadId + "aaaaaaaaaaaa的起始位置为:" + startIndex + " 结束位置为:" + endIndex);
112                 URL url = new URL(path);
113                 HttpURLConnection conn = (HttpURLConnection) url.openConnection();
114                 conn.setReadTimeout(5000);
115                 conn.setRequestMethod("GET");
116                 conn.setRequestProperty("Range", "bytes=" + startIndex + "-" + endIndex);
117                 int code = conn.getResponseCode();
118                 System.out.println("返回码是:" + code);
119                 InputStream is = conn.getInputStream();
120                 RandomAccessFile raf = new RandomAccessFile("/sdcard/360.exe", "rwd");
121                 raf.seek(startIndex);
122                 int len=0;
123                 byte[] buffer = new byte[1024];
124                 //位置计算
125                 int pos = startIndex;
126                 while((len = is.read(buffer)) != -1){
127                     RandomAccessFile info = new RandomAccessFile("/sdcard/" + threadId + ".txt", "rw");
128                     raf.write(buffer, 0, len);
129                     pos = pos + len;
130                     //System.out.println("线程" + threadId + "已经下载的" + pos);
131                     //设置进度条
132                     synchronized(MainActivity.this){
133                         currentLength = currentLength + len;
134                         pb.setProgress(currentLength);
135                     }
136                     
137                     info.write((pos + "").getBytes());
138                     info.close();
139                 }
140                 is.close();
141                 raf.close();
142                 System.out.println("线程" + threadId + "下载完毕!");
143             } catch (Exception e) {
144                 // TODO Auto-generated catch block
145                 e.printStackTrace();
146             }finally{
147                 liveThread--;
148                 if(liveThread == 0){
149                     for(int i=1; i <= threadCount; i++){
150                         File delFile = new File("/sdcard/" + i + ".txt");
151                         delFile.delete();
152                     }
153                     System.out.println("删除了文件");
154                 }
155             }
156             
157         }
158     }
159     @Override
160     public boolean onCreateOptionsMenu(Menu menu) {
161         // Inflate the menu; this adds items to the action bar if it is present.
162         getMenuInflater().inflate(R.menu.main, menu);
163         return true;
164     }
165     
166 }