Android通过HTTP协议实现断点续传下载实例

概述整理文档，搜刮出一个Android通过HTTP协议实现断点续传下载的代码，稍微整理精简一下做下分享。

整理文档，搜刮出一个AndroID通过http协议实现断点续传下载的代码，稍微整理精简一下做下分享。

fileDownloader.java                                                                                                                

package cn.itcast.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 cn.itcast.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];                 httpURLConnection conn = (httpURLConnection) url.openConnection();       conn.setConnectTimeout(5*1000);       conn.setRequestMethod("GET");       conn.setRequestProperty("Accept","image/gif,image/jpeg,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    */   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,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);   } } 

DownloadThread.Java

package cn.itcast.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",*/*");         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,1024)) != -1) {           threadfile.write(buffer,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.java

package cn.itcast.net.download;  public interface DownloadProgressListener {   public voID onDownloadSize(int size); } 

DBOpenHelper.java

package cn.itcast.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 = "itcast.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);   }  } 

fileService.java

package cn.itcast.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,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();   }    } 

DownloadActivity.java

package cn.itcast.download;  import java.io.file;  import cn.itcast.net.download.DownloadProgressListener; import cn.itcast.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.Widget.button; import androID.Widget.EditText; import androID.Widget.Progressbar; import androID.Widget.TextVIEw; import androID.Widget.Toast;  public class DownloadActivity 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(DownloadActivity.this,R.string.success,1).show();         }         break;        case -1:         Toast.makeText(DownloadActivity.this,R.string.error,1).show();         break;       }     }   };      @OverrIDe   public voID onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);     setContentVIEw(R.layout.main);          downloadpathText = (EditText) this.findVIEwByID(R.ID.downloadpath);     progressbar = (Progressbar) this.findVIEwByID(R.ID.downloadbar);     resultVIEw = (TextVIEw) this.findVIEwByID(R.ID.result);     button button = (button) this.findVIEwByID(R.ID.button);     button.setonClickListener(new VIEw.OnClickListener() {            @OverrIDe       public voID onClick(VIEw v) {         String path = downloadpathText.getText().toString();         if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){           download(path,Environment.getExternalStorageDirectory());         }else{           Toast.makeText(DownloadActivity.this,R.string.sdcarderror,1).show();         }                }     });   }   //主线程(UI线程)   //业务逻辑正确，但是该程序运行的时候有问题   //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   private voID download(final String path,final file savedir) {     new Thread(new Runnable() {            @OverrIDe       public voID run() {         fileDownloader loader = new fileDownloader(DownloadActivity.this,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();   } } 

demo下载：MulThreadDownload_jb51.rar

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