The implementation principle of multi‑thread download and resumable data transfer ., Multi-thread resumable upload

The implementation principle of multi‑thread download and resumable data transfer ., Multi-thread resumable upload

Package com. zzw. constant; public class Contant {public static int threadCount = 3;} 1 package com. zzw. download; 2 3 import java. io. bufferedReader; 4 import java. io. file; 5 import java. io. fileInputStream; 6 import java. io. fileOutputStream; 7 import java. io. IOException; 8 import java. io. inputStream; 9 import java. io. inputStreamReader; 10 import java. io. randomAccessFile; 11 import java.net. httpURLConn Ection; 12 import java.net. malformedURLException; 13 import java.net. URL; 14 import java.net. URLConnection; 15 16 import javax. tools. fileObject; 17 18 import com. zzw. constant. contant; 19 20 public class TestDownload 21 {22 // public static int threadCount = 3; 23 public static int blockSize = 0; 24 25 public static void main (String [] args) throws Exception 26 {27 URL url = new URL ("http: // localho St: 8080/download/cc.zip "); 28 29 HttpURLConnection conn = (HttpURLConnection) url. openConnection (); 30 conn. setRequestMethod ("GET"); 31 conn. setReadTimeout (10000); 32 33 long length = conn. getContentLength (); 34 35 conn. connect (); // connect 36 File file = new File ("cc.zip"); 37 38 RandomAccessFile randomFile = new RandomAccessFile (file, "rwd"); 39 randomFile. setLength (length); 40 41 // The download size of each thread is 42 S Ystem. out. println ("total size:" + length); 43 blockSize = (int) (length/Contant. threadCount); 44 System. out. println ("Download size of each thread:" + blockSize); 45 long start = 1; 46 long end = 0; 47 for (int I = 1; I <(Contant. threadCount + 1); I ++) 48 {49 50 // 1> 0-46354938 123456 51 // 2> 46354939-(46354939 + 46354938) 52 // 3> 53 start = blockSize * (I-1); 54 end = blockSize * I-1; 55 if (I = Contant. threadCoun T) 56 {57 end = length; 58} 59 System. out. println ("the" + I + "thread download interval:" + start + "-" + end); 60 new downloadThread (file, I, start, end ). start (); 61} 62 63 conn. disconnect (); 64} 65} 66 67 class downloadThread extends Thread 68 {69 private File path; // address of the local disk 70 private String url = "http: // localhost: 8080/download/cc.zip "; // the address of the HTTP request 71 private Integer threadID; // The number of threads currently 72 private lo Ng start; // start position of the thread to download 73 private long end; // end position of the thread 74 75 public downloadThread (File path, Integer threadID, long start, 76 long end) {77 this. path = path; 78 this. threadID = threadID; 79 this. start = start; 80 this. end = end; 81 82} 83 84 @ Override 85 public void run () 86 {87 try {88 System. out. println (threadID + "Enable Read"); 89 File contextFile = new File (threadID + ". txt "); 90 if (! ContextFile. exists () 91 {92 contextFile. createNewFile (); 93} 94 95 // read the data in the disconnection information to re-specify where to start writing 96 BufferedReader reader = new BufferedReader (new InputStreamReader (new FileInputStream (contextFile ))); 97 String info = reader. readLine (); 98 if (null! = Info & info. length ()> 0) 99 {100 start = start + Integer. parseInt (info); 101} 102 103 System. out. println ("start ........ = "+ start); 104 URL uri = new URL (url); 105 HttpURLConnection conn = (HttpURLConnection) uri. openconnections (); 106 conn. setRequestProperty ("Range", "bytes =" + start + "-" + end); 107 conn. setReadTimeout (50000); 108 conn. setConnectTimeout (50000); 109 110 conn. connect (); 111 112 // make the http request only Request a segment 113 System. out. println ("bytes =" + start + "-" + end); 114 115 200 // determine if it is? 116 int status = conn. getResponseCode (); 117 118 if (status/100 = 2) 119 {120 int total = 0; // The total number of bytes downloaded is 121. // FileOutputStream out = new FileOutputStream (new File (threadID + ". txt "); unreliable 122 RandomAccessFile random = new RandomAccessFile (path," rw "); 123 124 random. seek (start); 125 InputStream in = conn. getInputStream (); 126 byte [] buffer = new byte [1024]; 127 int len = 0; 128 129 while (len = in. read (bu Ffer ))! =-1) 130 {131 RandomAccessFile duandian = new RandomAccessFile (contextFile, "rwd"); 132 random. write (buffer, 0, len); 133 total + = len; 134 duandian. write (String. valueOf (total ). getBytes (); 135 duandian. close (); 136} 137 in. close (); 138 random. close (); 139} 140 conn. disconnect (); 141 System. out. println (threadID + "read completed"); 142} catch (MalformedURLException e) {143 e. printStackTrace (); 144} catch (IOException e) {145 e. printStackTrace (); 146} finally147 {148 synchronized (TestDownload. class) 149 {150 Contant. threadCount --; 151 System. out. println ("Contant. threadCount = "+ Contant. threadCount); 152 if (Contant. threadCount = 0) 153 {154 for (int I = 1; I <4; I ++) 155 {156 File contextFile = new File (I + ". txt "); 157 System. out. println (contextFile. delete () + "ccc"); 158} 159} 160} 161} 162} 163}