Android多线程断点续传下载实现代码

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import...;

public class MainActivity extends AppCompatActivity {

  private EditText et_path;
  private EditText et_threadCount;
  private LinearLayout ll_pb;
  private String path;

  private static int runningThread;// 代表正在运行的线程
  private int threadCount;
  private List pbList;//集合存储进度条的引用

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    et_path = findViewById(R.id.et_path);
    et_threadCount = findViewById(R.id.et_threadCount);
    ll_pb = findViewById(R.id.ll_pb);
    //添加一个进度条的引用
    pbList = new ArrayList();
  }

  //点击按钮实现下载逻辑
  public void click(View view) {
    //获取下载路径
    path = et_path.getText().toString().trim();
    //获取线程数量
    String threadCounts = et_threadCount.getText().toString().trim();
    //移除以前的进度条添加新的进度条
    ll_pb.removeAllViews();
    threadCount = Integer.parseInt(threadCounts);
    pbList.clear();
    for (int i = 0; i  0) {
          FileInputStream fis = new FileInputStream(file);
          BufferedReader bufr = new BufferedReader(new InputStreamReader(fis));
          String lastPosition = bufr.readLine();
          int lastPosition1 = Integer.parseInt(lastPosition);

          //赋值给进度条位置
          pblastPosition = lastPosition1 - startIndex;
          // 改变一下startIndex的值
          startIndex = lastPosition1 + 1;
          System.out.println("线程id：" + threadID + "真实下载的位置：" + lastPosition + "-------" + endIndex);

          bufr.close();
          fis.close();

        }

        conn.setRequestProperty("Range", "bytes=" + startIndex + "-" + endIndex);
        int code = conn.getResponseCode();
        if (code == 206) {
          // 随机读写文件对象
          RandomAccessFile raf = new RandomAccessFile(getFileName(path), "rw");
          // 每个线程从自己的位置开始写

          raf.seek(startIndex);
          InputStream in = conn.getInputStream();
          // 把数据写到文件中
          int len = -1;
          byte[] buffer = new byte[1024];
          int totle = 0;// 代表当前线程下载的大小
          while ((len = in.read(buffer)) != -1) {
            raf.write(buffer, 0, len);
            totle += len;

            // 实现断点续传就是把当前线程下载的位置保存起来，下次再下载的时候按照上次下载的位置继续下载
            int currentThreadPosition = startIndex + totle;// 存到一个txt文本中
            // 用来存储当前线程当前下载的位置
            RandomAccessFile raff = new RandomAccessFile(getFileName(path) + threadID + ".txt", "rwd");
            raff.write(String.valueOf(currentThreadPosition).getBytes());
            raff.close();

            //设置进度条当前的进度
            pbList.get(threadID).setMax(PbMaxSize);
            pbList.get(threadID).setProgress(pblastPosition + totle);
          }
          raf.close();
          System.out.println("线程ID:" + threadID + "下载完成");
          // 将产生的txt文件删除，每个线程下载完成的具体时间不知道
          synchronized (DownLoadThread.class) {
            runningThread--;
            if (runningThread == 0) {
              //说明线程执行完毕
              for (int i = 0; i