Android入门：多线程断点下载详细介绍

package 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 = "download.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 service;  import java.util.HashMap; import java.util.Map;  import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; /**  * 业务bean  *  */ 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 net.download;  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 service.FileService; import android.content.Context; import android.util.Log; /**  * 文件下载器  * FileDownloader loader = new FileDownloader(context, "http://browse.babasport.com/ejb3/ActivePort.exe",         new File("D://androidsoft//test"), 2);     loader.getFileSize();//得到文件总大小     try {       loader.download(new DownloadProgressListener(){         public void onDownloadSize(int size) {           print("已经下载："+ size);         }            });     } catch (Exception e) {       e.printStackTrace();     }  */ 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];       //1.获得文件大小       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                  //2.如果以前已经下载过，则从数据库中导入记录，并继续下载                  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    */   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);       //如果线程数与以前不一样，则重新开始下       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 net.download;  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;   } } DownloadProgressListener.javapackage net.download;  //下载监听器 public interface DownloadProgressListener {   public void onDownloadSize(int size); } 

package org.xiazdong.download;  import java.io.File;  import net.download.DownloadProgressListener; import net.download.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.view.View.OnClickListener; 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 Button downloadButton;   private EditText urlpathEditText;   private TextView percentTextView;   private ProgressBar progressBar;   private Handler handler;   //主线程   private class UIHandler extends Handler{     @Override     public void handleMessage(Message msg) {       int downloadsize = msg.getData().getInt("downloadsize");       int percent = msg.getData().getInt("percent");       progressBar.setProgress(downloadsize);       percentTextView.setText(percent+"%");     }   }   private OnClickListener listener = new OnClickListener() {     DownloadThread thread;     class DownloadThread extends Thread{       private String url ;       private File saveDir;       private FileDownloader download;       public DownloadThread(String url, File saveDir) {         this.url = url;         this.saveDir = saveDir;       }       //子线程       @Override       public void run() {         download = new FileDownloader(MainActivity.this,url, saveDir, 3);         progressBar.setMax(download.getFileSize()); //设置最大刻度         try {           download.download(downListener);         } catch (Exception e) {           e.printStackTrace();         }       }     }     //由子线程调用     private DownloadProgressListener downListener = new DownloadProgressListener() {       @Override       public void onDownloadSize(int size) {         //实时跟踪下载的情况         int percent = (int)(((double)size)/progressBar.getMax()*100);         Message msg = new Message();         msg.what = 1;  //设置id         System.out.println(percent+"%");         System.out.println(size+"k");         msg.getData().putInt("percent", percent);         msg.getData().putInt("downloadsize",size);         handler.sendMessage(msg);                }     };          @Override     public void onClick(View v) {       if(v==downloadButton){         if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){           String url = urlpathEditText.getText().toString();           File saveDir = Environment.getExternalStorageDirectory();           download(url,saveDir);         }         else{           Toast.makeText(MainActivity.this, "SDCARD不存在", Toast.LENGTH_SHORT).show();         }       }     }      private void download(String url, File saveDir) {       thread = new DownloadThread(url,saveDir);       thread.start();            }   };   @Override   public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentView(R.layout.main);     downloadButton = (Button)findViewById(R.id.download);     urlpathEditText = (EditText)findViewById(R.id.path);     percentTextView = (TextView)findViewById(R.id.textView);     progressBar = (ProgressBar)findViewById(R.id.progressBar);      downloadButton.setOnClickListener(listener);     handler = new UIHandler();   } }