PC版与Android手机版带断点续传的多线程下载

 public class MultiDownload {    static int ThreadCount = ;    static int finishedThread = ;    //确定下载地址    static String filename = "EditPlus.exe";    static String path = "http://...:/"+filename;    public static void main(String[] args) {      //、发送get请求，去获得下载文件的长度     try {       URL url = new URL(path);       HttpURLConnection conn = (HttpURLConnection) url.openConnection();       conn.setRequestMethod("GET");       conn.setConnectTimeout();       conn.setReadTimeout();       if (conn.getResponseCode()==) {         //如果请求成功，拿到所请求资源文件的长度         int length = conn.getContentLength();         //、生成一个与原文件同样的大小的临时文件，以免下载一半存储空间不够了         File file = new File(filename);//演示，所以将保存的文件目录放在工程的同目录         //使用RandomAccessFile 生成临时文件，可以用指针定位文件的任意位置，         //而且能够实时写到硬件底层设备，略过缓存，这对下载文件是突然断电等意外是有好处的         RandomAccessFile raf = new RandomAccessFile(file, "rwd");//rwd, 实时写到底层设备         //设置临时文件的大小         raf.setLength(length);         raf.close();         //、计算出每个线程应该下载多少个字节         int size = length/ThreadCount;//如果有余数，负责最后一部分的线程负责下砸         //开启多线程         for (int threadId = ; threadId < ThreadCount; threadId++) {           //计算每个线程下载的开始位置和结束位置           int startIndex = threadId*size; // 开始 = 线程id * size           int endIndex = (threadId+)*size - ; //结束 = （线程id + )*size -            //如果是最后一个线程，那么结束位置写死为文件结束位置           if (threadId == ThreadCount - ) {             endIndex = length - ;           }           //System.out.println("线程"+threadId+"的下载区间是： "+startIndex+"----"+endIndex);           new DownloadThread(startIndex,endIndex,threadId).start();         }       }     } catch (MalformedURLException e) {       e.printStackTrace();     } catch (IOException e) {       e.printStackTrace();     }   } } class DownloadThread extends Thread{   private int startIndex;   private int endIndex;   private int threadId;   public DownloadThread(int startIndex, int endIndex, int threadId) {     super();     this.startIndex = startIndex;     this.endIndex = endIndex;     this.threadId = threadId;   }    public void run() {      //每个线程再次发送http请求，下载自己对应的那部分数据     try {       File progressFile = new File(threadId+".txt");       //判断进度文件是否存在，如果存在，则接着断点继续下载，如果不存在，则从头下载       if (progressFile.exists()) {         FileInputStream fis = new FileInputStream(progressFile);         BufferedReader br = new BufferedReader(new InputStreamReader(fis));         //从进度文件中度取出上一次下载的总进度，然后与原本的开始进度相加，得到新的开始进度         startIndex += Integer.parseInt(br.readLine());         fis.close();       }       System.out.println("线程"+threadId+"的下载区间是:"+startIndex+"----"+endIndex);       //、每个线程发送http请求自己的数据       URL url = new URL(MultiDownload.path);       HttpURLConnection conn = (HttpURLConnection) url.openConnection();       conn.setRequestMethod("GET");       conn.setConnectTimeout();       conn.setReadTimeout();       //设置本次http请求所请求的数据的区间       conn.setRequestProperty("Range", "bytes="+startIndex+"-"+endIndex);       //请求部分数据，响应码是       if (conn.getResponseCode()==) {         //此时，流里只有ThreadCount分之一的原文件数据         InputStream is = conn.getInputStream();         byte[] b = new byte[];         int len = ;         int total = ;//total 用于保存断点续传的断点         //拿到临时文件的输出流         File file = new File(MultiDownload.filename);         RandomAccessFile raf = new RandomAccessFile(file, "rwd");         //把文件的写入位置移动至 startIndex         raf.seek(startIndex);         while ((len = is.read(b))!=-) {           //每次读取流里数据之后，同步把数据写入临时文件           raf.write(b, , len);           total += len;           //System.out.println("线程" + threadId + "下载了" + total);           //生成一个一个专门用来记录下载进度的临时文件           RandomAccessFile progressRaf = new RandomAccessFile(progressFile, "rwd");           progressRaf.write((total+"").getBytes());           progressRaf.close();         }         System.out.println("线程"+threadId+"下载完了---------------------");         raf.close();         //当所有的线程下载完之后，将进度文件删除         MultiDownload.finishedThread++;         synchronized (MultiDownload.path) {//所有线程使用同一个锁           if (MultiDownload.finishedThread==MultiDownload.ThreadCount) {             for (int i = ; i < MultiDownload.ThreadCount; i++) {               File f = new File(i+".txt");               f.delete();             }             MultiDownload.finishedThread=;           }         }       }       } catch (Exception e) {       e.printStackTrace();     }   } }

public class MainActivity extends Activity {  static int ThreadCount = ;  static int FinishedThread = ;  int currentProgess;  static String Filename = "QQPlayer.exe";  static String Path = "http://...:/"+Filename;  static MainActivity ma;  static ProgressBar pb;  static TextView tv;  static Handler handler = new Handler(){    public void handleMessage(android.os.Message msg){      tv.setText((long)pb.getProgress()* /pb.getMax() +"%");    };  };  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    ma = this;    pb = (ProgressBar) findViewById(R.id.pb);    tv = (TextView) findViewById(R.id.tv);  }  public void download(View v){    Thread t = new Thread(){      public void run() {        //发送http请求获取文件的长度，创建临时文件        try {          URL url= new URL(Path);          HttpURLConnection conn = (HttpURLConnection) url.openConnection();          conn.setRequestMethod("GET");          conn.setConnectTimeout();          conn.setReadTimeout();          if (conn.getResponseCode()==) {            int length = conn.getContentLength();            //设置进度条的最大值就是原文件的总长度            pb.setMax(length);            //生成一个与原文件相同大小的临时文件            File file = new File(Environment.getExternalStorageDirectory(),Filename);            RandomAccessFile raf = new RandomAccessFile(file, "rwd");            raf.setLength(length);            raf.close();            //计算每个线程需要下载的数据大小            int size = length/ThreadCount;            //开启多线程            for (int threadId = ; threadId < ThreadCount; threadId++) {              int startIndex = threadId*size;              int endIndex = (threadId + )*size - ;              if (threadId==ThreadCount - ) {                endIndex = length - ;              }              new DownloadThread(startIndex, endIndex, threadId).start();            }          }        } catch (Exception e) {          e.printStackTrace();        }      }    };    t.start();  }  class DownloadThread extends Thread{    private int startIndex;    private int endIndex;    private int threadId;    public DownloadThread(int startIndex, int endIndex, int threadId) {      super();      this.startIndex = startIndex;      this.endIndex = endIndex;      this.threadId = threadId;    }    public void run() {      // 每个线程发送http请求自己的数据      try{        //先判断是不是断点续传        File progessFile = new File(Environment.getExternalStorageDirectory(),threadId+".txt");        if (progessFile.exists()) {          FileReader fr = new FileReader(progessFile);          BufferedReader br = new BufferedReader(fr);          int lastProgess = Integer.parseInt(br.readLine());          startIndex += lastProgess;          //把上次下载的进度显示至进度条          currentProgess +=lastProgess;          pb.setProgress(currentProgess);          //发消息，让主线程刷新文本进度          handler.sendEmptyMessage();          br.close();          fr.close();        }        URL url = new URL(Path);        HttpURLConnection conn = (HttpURLConnection) url.openConnection();        conn.setRequestMethod("GET");        conn.setConnectTimeout();        conn.setReadTimeout();        conn.setRequestProperty("Range", "bytes="+startIndex+"-"+endIndex);        if (conn.getResponseCode()==) {          InputStream is = conn.getInputStream();          byte[] buffer = new byte[];          int len = ;          int total = ;          File file = new File(Environment.getExternalStorageDirectory(),Filename);          RandomAccessFile raf = new RandomAccessFile(file, "rwd");          raf.seek(startIndex);          while ((len = is.read(buffer))!= -) {            raf.write(buffer, , len);            total += len;            //每次读取流里数据之后，把本次读取的数据的长度显示至进度条            currentProgess += len;            pb.setProgress(currentProgess);            //发消息，让主线程刷新文本进度            handler.sendEmptyMessage();            //生成临时文件保存下载进度，用于断点续传，在所有线程现在完毕后删除临时文件            RandomAccessFile progressRaf = new RandomAccessFile(progessFile, "rwd");            progressRaf.write((total+"").getBytes());            progressRaf.close();          }          raf.close();          System.out.println("线程"+threadId+"下载完了");          //当所有线程都下在完了之后，删除临时进度文件          FinishedThread++;          synchronized (Path) {            if (FinishedThread==ThreadCount) {              for (int i = ; i < ThreadCount; i++) {                File f = new File(Environment.getExternalStorageDirectory(),i+".txt");                f.delete();              }              FinishedThread=;            }          }        }      } catch (Exception e) {        e.printStackTrace();      }    }  }}