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實(shí)現(xiàn)android 上面多線程斷點(diǎn)續(xù)傳下載 ，支持暫停，記憶任務(wù)。
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源碼片段

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(, null); // 設(shè)置客戶端可以接受的返回?cái)?shù)據(jù)類型 
                  
                http.setRequestProperty("Accept-Language", "zh-CN"); 
                http.setRequestProperty("Referer", downUrl.toString());// 設(shè)置請(qǐng)求的來源，便于對(duì)訪問來源進(jìn)行統(tǒng)計(jì) 
                http.setRequestProperty("Charset", "UTF-8"); 
  
                // 計(jì)算該線程下載的開始位置 
                int startPos = block * (threadId - 1) + downloadedLength; 
                  
                /** 
                 * 每塊結(jié)束的位置（***一塊需特殊處理，因?yàn)椴荒芷骄峙涿繅K大下，***一塊可能會(huì)有余數(shù)） 
                 */ 
                //int endPosition = (i + 1) != threadCount ? ((i + 1) * blockSize - 1): fileSize; 
                // 計(jì)算該線程下載的結(jié)束位置 
                int endPos = threadId!=threadCount? (block *threadId):fileSize; 
                // 設(shè)置獲取實(shí)體數(shù)據(jù)的范圍,如果超過了實(shí)體數(shù)據(jù)的大小會(huì)自動(dòng)返回實(shí)際的數(shù)據(jù)大小 
                http.setRequestProperty("Range", "bytes=" + startPos + "-"+ endPos); 
                // 客戶端用戶代理 
                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)"); 
  
                // 使用長連接 
                http.setRequestProperty("Connection", "Keep-Alive"); 
                // 獲取遠(yuǎn)程連接的輸入流 
                InputStream inStream = http.getInputStream(); 
                // 設(shè)置本地?cái)?shù)據(jù)緩存的大小為1M 
                byte[] buffer = new byte[1024]; 
                // 設(shè)置每次讀取的數(shù)據(jù)量 
                int offset = 0; 
                // 打印該線程開始下載的位置 
                print("Thread " + this.threadId 
                        + " starts to download from position " + startPos); 
                RandomAccessFile threadFile = new RandomAccessFile( 
                        this.saveFile, "rwd"); 
                // 文件指針指向開始下載的位置 
                threadFile.seek(startPos); 

源碼鏈接：http://down.51cto.com/data/1980815