Android实现网络多线程断点续传下载实例

HttpURLConnection.getContentLength();//获取下载文件的长度RandomAccessFile file = new RandomAccessFile("QQWubiSetup.exe","rwd");file.setLength(filesize);//设置本地文件的长度

 <?xml version="1.0" encoding="utf-8"?> <resources>  <string name="hello">Hello World, MainActivity!</string>  <string name="app_name">Android网络多线程断点下载</string>  <string name="path">下载路径</string>  <string name="downloadbutton">下载</string>  <string name="sdcarderror">SDCard不存在或者写保护</string>  <string name="success">下载完成</string>  <string name="error">下载失败</string></resources>

 <?xml version="1.0" encoding="utf-8"?>  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:orientation="vertical"  android:layout_width="fill_parent"  android:layout_height="fill_parent">  <!-- 下载路径 -->  <TextView    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:text="@string/path"/>  <EditText     android:id="@+id/path"     android:text="http://www.winrar.com.cn/download/wrar380sc.exe"     android:layout_width="fill_parent"     android:layout_height="wrap_content">  </EditText>  <!-- 下载按钮 -->  <Button    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="@string/downloadbutton"    android:id="@+id/button"/>  <!-- 进度条 -->  <ProgressBar    android:layout_width="fill_parent"    android:layout_height="20dip"    style="?android:attr/progressBarStyleHorizontal"    android:id="@+id/downloadbar" />  <TextView    android:layout_width="fill_parent"    android:layout_height="wrap_content"    android:gravity="center"    android:id="@+id/resultView" />  </LinearLayout>

 <?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"   package="com.android.downloader"   android:versionCode="1"   android:versionName="1.0">  <uses-sdk android:minSdkVersion="8" />  <application android:icon="@drawable/icon" android:label="@string/app_name">    <activity android:name=".MainActivity"         android:label="@string/app_name">      <intent-filter>        <action android:name="android.intent.action.MAIN" />        <category android:name="android.intent.category.LAUNCHER" />      </intent-filter>    </activity>  </application>    <!-- 在SDCard中创建与删除文件权限 -->  <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>    <!-- 往SDCard写入数据权限 -->  <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>    <!-- 访问internet权限 -->  <uses-permission android:name="android.permission.INTERNET"/></manifest>

 package com.android.downloader;import java.io.File; import com.android.network.DownloadProgressListener;import com.android.network.FileDownloader; import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.ProgressBar;import android.widget.TextView;import android.widget.Toast; public class MainActivity extends Activity {  private EditText downloadpathText;  private TextView resultView;  private ProgressBar progressBar;    /**   * 当Handler被创建会关联到创建它的当前线程的消息队列，该类用于往消息队列发送消息   * 消息队列中的消息由当前线程内部进行处理   */  private Handler handler = new Handler(){     @Override    public void handleMessage(Message msg) {            switch (msg.what) {      case 1:                progressBar.setProgress(msg.getData().getInt("size"));        float num = (float)progressBar.getProgress()/(float)progressBar.getMax();        int result = (int)(num*100);        resultView.setText(result+ "%");                if(progressBar.getProgress()==progressBar.getMax()){          Toast.makeText(MainActivity.this, R.string.success, 1).show();        }        break;      case -1:        Toast.makeText(MainActivity.this, R.string.error, 1).show();        break;      }    }  };    /** Called when the activity is first created. */  @Override  public void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.main);        downloadpathText = (EditText) this.findViewById(R.id.path);    progressBar = (ProgressBar) this.findViewById(R.id.downloadbar);    resultView = (TextView) this.findViewById(R.id.resultView);    Button button = (Button) this.findViewById(R.id.button);        button.setOnClickListener(new View.OnClickListener() {            @Override      public void onClick(View v) {        // TODO Auto-generated method stub        String path = downloadpathText.getText().toString();        System.out.println(Environment.getExternalStorageState()+"------"+Environment.MEDIA_MOUNTED);                if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){          download(path, Environment.getExternalStorageDirectory());        }else{          Toast.makeText(MainActivity.this, R.string.sdcarderror, 1).show();        }      }    });  }     /**    * 主线程(UI线程)    * 对于显示控件的界面更新只是由UI线程负责，如果是在非UI线程更新控件的属性值，更新后的显示界面不会反映到屏幕上    * @param path    * @param savedir    */  private void download(final String path, final File savedir) {    new Thread(new Runnable() {            @Override      public void run() {        FileDownloader loader = new FileDownloader(MainActivity.this, path, savedir, 3);        progressBar.setMax(loader.getFileSize());//设置进度条的最大刻度为文件的长度                try {          loader.download(new DownloadProgressListener() {            @Override            public void onDownloadSize(int size) {//实时获知文件已经下载的数据长度              Message msg = new Message();              msg.what = 1;              msg.getData().putInt("size", size);              handler.sendMessage(msg);//发送消息            }          });        } catch (Exception e) {          handler.obtainMessage(-1).sendToTarget();        }      }    }).start();  }}

package com.android.service;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper; public class DBOpenHelper extends SQLiteOpenHelper {  private static final String DBNAME = "down.db";  private static final int VERSION = 1;    public DBOpenHelper(Context context) {    super(context, DBNAME, null, VERSION);  }    @Override  public void onCreate(SQLiteDatabase db) {    db.execSQL("CREATE TABLE IF NOT EXISTS filedownlog (id integer primary key autoincrement, downpath varchar(100), threadid INTEGER, downlength INTEGER)");  }   @Override  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    db.execSQL("DROP TABLE IF EXISTS filedownlog");    onCreate(db);  }}

package com.android.service;import java.util.HashMap;import java.util.Map; import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase; public class FileService {  private DBOpenHelper openHelper;   public FileService(Context context) {    openHelper = new DBOpenHelper(context);  }    /**   * 获取每条线程已经下载的文件长度   * @param path   * @return   */  public Map<Integer, Integer> getData(String path){    SQLiteDatabase db = openHelper.getReadableDatabase();    Cursor cursor = db.rawQuery("select threadid, downlength from filedownlog where downpath=?", new String[]{path});    Map<Integer, Integer> data = new HashMap<Integer, Integer>();        while(cursor.moveToNext()){      data.put(cursor.getInt(0), cursor.getInt(1));    }        cursor.close();    db.close();    return data;  }    /**   * 保存每条线程已经下载的文件长度   * @param path   * @param map   */  public void save(String path, Map<Integer, Integer> map){//int threadid, int position    SQLiteDatabase db = openHelper.getWritableDatabase();    db.beginTransaction();        try{      for(Map.Entry<Integer, Integer> entry : map.entrySet()){        db.execSQL("insert into filedownlog(downpath, threadid, downlength) values(?,?,?)",            new Object[]{path, entry.getKey(), entry.getValue()});      }      db.setTransactionSuccessful();    }finally{      db.endTransaction();    }        db.close();  }    /**   * 实时更新每条线程已经下载的文件长度   * @param path   * @param map   */  public void update(String path, Map<Integer, Integer> map){    SQLiteDatabase db = openHelper.getWritableDatabase();    db.beginTransaction();        try{      for(Map.Entry<Integer, Integer> entry : map.entrySet()){        db.execSQL("update filedownlog set downlength=? where downpath=? and threadid=?",            new Object[]{entry.getValue(), path, entry.getKey()});      }            db.setTransactionSuccessful();    }finally{      db.endTransaction();    }        db.close();  }    /**   * 当文件下载完成后，删除对应的下载记录   * @param path   */  public void delete(String path){    SQLiteDatabase db = openHelper.getWritableDatabase();    db.execSQL("delete from filedownlog where downpath=?", new Object[]{path});    db.close();  }}

package com.android.network;public interface DownloadProgressListener {  public void onDownloadSize(int size);} 

package com.android.network;import java.io.File;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.URL;import java.util.LinkedHashMap;import java.util.Map;import java.util.UUID;import java.util.concurrent.ConcurrentHashMap;import java.util.regex.Matcher;import java.util.regex.Pattern;import com.android.service.FileService;import android.content.Context;import android.util.Log;public class FileDownloader {  private static final String TAG = "FileDownloader";  private Context context;  private FileService fileService;     /* 已下载文件长度 */  private int downloadSize = 0;  /* 原始文件长度 */  private int fileSize = 0;  /* 线程数 */  private DownloadThread[] threads;  /* 本地保存文件 */  private File saveFile;  /* 缓存各线程下载的长度*/  private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();   /* 每条线程下载的长度 */  private int block;  /* 下载路径 */  private String downloadUrl;  /**   * 获取线程数   */  public int getThreadSize() {    return threads.length;  }  /**   * 获取文件大小   * @return   */  public int getFileSize() {    return fileSize;  }   /**   * 累计已下载大小   * @param size   */  protected synchronized void append(int size) {    downloadSize += size;  }  /**   * 更新指定线程最后下载的位置   * @param threadId 线程id   * @param pos 最后下载的位置   */  protected synchronized void update(int threadId, int pos) {    this.data.put(threadId, pos);    this.fileService.update(this.downloadUrl, this.data);  }  /**   * 构建文件下载器   * @param downloadUrl 下载路径   * @param fileSaveDir 文件保存目录   * @param threadNum 下载线程数   */  public FileDownloader(Context context, String downloadUrl, File fileSaveDir, int threadNum) {    try {      this.context = context;      this.downloadUrl = downloadUrl;      fileService = new FileService(this.context);      URL url = new URL(this.downloadUrl);      if(!fileSaveDir.exists()) fileSaveDir.mkdirs();      this.threads = new DownloadThread[threadNum];                HttpURLConnection conn = (HttpURLConnection) url.openConnection();      conn.setConnectTimeout(5*1000);      conn.setRequestMethod("GET");      conn.setRequestProperty("Accept", "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");      conn.setRequestProperty("Accept-Language", "zh-CN");      conn.setRequestProperty("Referer", downloadUrl);       conn.setRequestProperty("Charset", "UTF-8");      conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");      conn.setRequestProperty("Connection", "Keep-Alive");      conn.connect();      printResponseHeader(conn);      if (conn.getResponseCode()==200) {        this.fileSize = conn.getContentLength();//根据响应获取文件大小        if (this.fileSize <= 0) throw new RuntimeException("Unkown file size ");        String filename = getFileName(conn);//获取文件名称        this.saveFile = new File(fileSaveDir, filename);//构建保存文件        Map<Integer, Integer> logdata = fileService.getData(downloadUrl);//获取下载记录        if(logdata.size()>0){//如果存在下载记录          for(Map.Entry<Integer, Integer> entry : logdata.entrySet())            data.put(entry.getKey(), entry.getValue());//把各条线程已经下载的数据长度放入data中        }        if(this.data.size()==this.threads.length){//下面计算所有线程已经下载的数据长度          for (int i = 0; i < this.threads.length; i++) {            this.downloadSize += this.data.get(i+1);          }          print("已经下载的长度"+ this.downloadSize);        }        //计算每条线程下载的数据长度        this.block = (this.fileSize % this.threads.length)==0? this.fileSize / this.threads.length : this.fileSize / this.threads.length + 1;      }else{        throw new RuntimeException("server no response ");      }    } catch (Exception e) {      print(e.toString());      throw new RuntimeException("don't connection this url");    }  }  /**   * 获取文件名   * @param conn   * @return   */  private String getFileName(HttpURLConnection conn) {    String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1);    if(filename==null || "".equals(filename.trim())){//如果获取不到文件名称      for (int i = 0;; i++) {        String mine = conn.getHeaderField(i);        if (mine == null) break;        if("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())){          Matcher m = Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase());          if(m.find()) return m.group(1);        }      }      filename = UUID.randomUUID()+ ".tmp";//默认取一个文件名    }    return filename;  }  /**   * 开始下载文件   * @param listener 监听下载数量的变化,如果不需要了解实时下载的数量,可以设置为null   * @return 已下载文件大小   * @throws Exception   */  public int download(DownloadProgressListener listener) throws Exception{    try {      RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw");      if(this.fileSize>0) randOut.setLength(this.fileSize);      randOut.close();      URL url = new URL(this.downloadUrl);      if(this.data.size() != this.threads.length){       this.data.clear();        for (int i = 0; i < this.threads.length; i++) {          this.data.put(i+1, 0);//初始化每条线程已经下载的数据长度为0        }      }      for (int i = 0; i < this.threads.length; i++) {//开启线程进行下载        int downLength = this.data.get(i+1);                if(downLength < this.block && this.downloadSize<this.fileSize){//判断线程是否已经完成下载,否则继续下载            this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1);          this.threads[i].setPriority(7);          this.threads[i].start();        }else{          this.threads[i] = null;        }      }      this.fileService.save(this.downloadUrl, this.data);      boolean notFinish = true;//下载未完成      while (notFinish) {// 循环判断所有线程是否完成下载        Thread.sleep(900);        notFinish = false;//假定全部线程下载完成                for (int i = 0; i < this.threads.length; i++){          if (this.threads[i] != null && !this.threads[i].isFinish()) {//如果发现线程未完成下载            notFinish = true;//设置标志为下载没有完成                        if(this.threads[i].getDownLength() == -1){//如果下载失败,再重新下载              this.threads[i] = new DownloadThread(this, url, this.saveFile, this.block, this.data.get(i+1), i+1);              this.threads[i].setPriority(7);              this.threads[i].start();            }          }        }          if(listener!=null) listener.onDownloadSize(this.downloadSize);//通知目前已经下载完成的数据长度      }      fileService.delete(this.downloadUrl);    } catch (Exception e) {      print(e.toString());      throw new Exception("file download fail");    }    return this.downloadSize;  }  /**   * 获取Http响应头字段   * @param http   * @return   */  public static Map<String, String> getHttpResponseHeader(HttpURLConnection http) {    Map<String, String> header = new LinkedHashMap<String, String>();        for (int i = 0;; i++) {      String mine = http.getHeaderField(i);      if (mine == null) break;      header.put(http.getHeaderFieldKey(i), mine);    }        return header;  }   /**   * 打印Http头字段   * @param http   */  public static void printResponseHeader(HttpURLConnection http){    Map<String, String> header = getHttpResponseHeader(http);        for(Map.Entry<String, String> entry : header.entrySet()){      String key = entry.getKey()!=null ? entry.getKey()+ ":" : "";      print(key+ entry.getValue());    }  }   private static void print(String msg){    Log.i(TAG, msg);  }}

package com.android.network;import java.io.File;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.HttpURLConnection;import java.net.URL;import android.util.Log;public class DownloadThread extends Thread {  private static final String TAG = "DownloadThread";  private File saveFile;  private URL downUrl;  private int block;    /* 下载开始位置 */  private int threadId = -1;    private int downLength;  private boolean finish = false;  private FileDownloader downloader;    public DownloadThread(FileDownloader downloader, URL downUrl, File saveFile, int block, int downLength, int threadId) {    this.downUrl = downUrl;    this.saveFile = saveFile;    this.block = block;    this.downloader = downloader;    this.threadId = threadId;    this.downLength = downLength;  }    @Override  public void run() {    if(downLength < block){//未下载完成      try {        HttpURLConnection http = (HttpURLConnection) downUrl.openConnection();        http.setConnectTimeout(5 * 1000);        http.setRequestMethod("GET");        http.setRequestProperty("Accept", "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");        http.setRequestProperty("Accept-Language", "zh-CN");        http.setRequestProperty("Referer", downUrl.toString());         http.setRequestProperty("Charset", "UTF-8");        int startPos = block * (threadId - 1) + downLength;//开始位置        int endPos = block * threadId -1;//结束位置        http.setRequestProperty("Range", "bytes=" + startPos + "-"+ endPos);//设置获取实体数据的范围        http.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");        http.setRequestProperty("Connection", "Keep-Alive");                InputStream inStream = http.getInputStream();        byte[] buffer = new byte[1024];        int offset = 0;        print("Thread " + this.threadId + " start download from position "+ startPos);        RandomAccessFile threadfile = new RandomAccessFile(this.saveFile, "rwd");        threadfile.seek(startPos);                while ((offset = inStream.read(buffer, 0, 1024)) != -1) {          threadfile.write(buffer, 0, offset);          downLength += offset;          downloader.update(this.threadId, downLength);          downloader.append(offset);        }                threadfile.close();        inStream.close();        print("Thread " + this.threadId + " download finish");        this.finish = true;      } catch (Exception e) {        this.downLength = -1;        print("Thread "+ this.threadId+ ":"+ e);      }    }  }  private static void print(String msg){    Log.i(TAG, msg);  }    /**   * 下载是否完成   * @return   */  public boolean isFinish() {    return finish;  }    /**   * 已经下载的内容大小   * @return 如果返回值为-1,代表下载失败   */  public long getDownLength() {    return downLength;  }}