Android之多线程断点下载

Posted by jjx on March 30, 2016

本文主要包含多线程下载的一些简单demo,包括三部分

  1. java实现
  2. android实现
  3. XUtils开源库实现

注意下载添加网络权限与SD卡读写权限

java实现多线程下载

public class MutileThreadDownload {
  /**
   * 线程的数量
   */
  private static int threadCount = 3;

  /**
   * 每个下载区块的大小
   */
  private static long blocksize;

  /**
   * 正在运行的线程的数量
   */
  private static int runningThreadCount;

  /**
   * @param args
   * @throws Exception
   */
  public static void main(String[] args) throws Exception {
    // 服务器文件的路径
    String path = "http://192.168.1.100:8080/ff.exe";
    URL url = new URL(path);
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setRequestMethod("GET");
    conn.setConnectTimeout(5000);
    int code = conn.getResponseCode();
    if (code == 200) {
      long size = conn.getContentLength();// 得到服务端返回的文件的大小
      System.out.println("服务器文件的大小:" + size);
      blocksize = size / threadCount;
      // 1.首先在本地创建一个大小跟服务器一模一样的空白文件。
      File file = new File("temp.exe");
      RandomAccessFile raf = new RandomAccessFile(file, "rw");
      raf.setLength(size);
      // 2.开启若干个子线程分别去下载对应的资源。
      runningThreadCount = threadCount;
      for (int i = 1; i <= threadCount; i++) {
        long startIndex = (i - 1) * blocksize;
        long endIndex = i * blocksize - 1;
        if (i == threadCount) {
          // 最后一个线程
          endIndex = size - 1;
        }
        System.out.println("开启线程:" + i + "下载的位置:" + startIndex + "~"
            + endIndex);
        new DownloadThread(path, i, startIndex, endIndex).start();
      }
    }
    conn.disconnect();
  }

  private static class DownloadThread extends Thread {
    private int threadId;
    private long startIndex;
    private long endIndex;
    private String path;

    public DownloadThread(String path, int threadId, long startIndex,
        long endIndex) {
      this.path = path;
      this.threadId = threadId;
      this.startIndex = startIndex;
      this.endIndex = endIndex;
    }

    @Override
    public void run() {
      try {
        // 当前线程下载的总大小
        int total = 0;
        File positionFile = new File(threadId + ".txt");
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url
            .openConnection();
        conn.setRequestMethod("GET");
        // 接着从上一次的位置继续下载数据
        if (positionFile.exists() && positionFile.length() > 0) {// 判断是否有记录
          FileInputStream fis = new FileInputStream(positionFile);
          BufferedReader br = new BufferedReader(
              new InputStreamReader(fis));
          // 获取当前线程上次下载的总大小是多少
          String lasttotalstr = br.readLine();
          int lastTotal = Integer.valueOf(lasttotalstr);
          System.out.println("上次线程" + threadId + "下载的总大小:"
              + lastTotal);
          startIndex += lastTotal;
          total += lastTotal;// 加上上次下载的总大小。
          fis.close();
        }

        conn.setRequestProperty("Range", "bytes=" + startIndex + "-"
            + endIndex);
        conn.setConnectTimeout(5000);
        int code = conn.getResponseCode();
        System.out.println("code=" + code);
        InputStream is = conn.getInputStream();
        File file = new File("temp.exe");
        RandomAccessFile raf = new RandomAccessFile(file, "rw");
        // 指定文件开始写的位置。
        raf.seek(startIndex);
        System.out.println("第" + threadId + "个线程:写文件的开始位置:"
            + String.valueOf(startIndex));
        int len = 0;
        byte[] buffer = new byte[512];
        while ((len = is.read(buffer)) != -1) {
          RandomAccessFile rf = new RandomAccessFile(positionFile,
              "rwd");
          raf.write(buffer, 0, len);
          total += len;
          rf.write(String.valueOf(total).getBytes());
          rf.close();
        }
        is.close();
        raf.close();

      } catch (Exception e) {
        e.printStackTrace();
      } finally {
        // 只有所有的线程都下载完毕后 才可以删除记录文件。
        synchronized (MutileThreadDownload.class) {
          System.out.println("线程" + threadId + "下载完毕了");
          runningThreadCount--;
          if (runningThreadCount < 1) {
            System.out.println("所有的线程都工作完毕了。删除临时记录的文件");
            for (int i = 1; i <= threadCount; i++) {
              File f = new File(i + ".txt");
              System.out.println(f.delete());
            }
          }
        }

      }
    }
  }
}

安卓实现

public class MainActivity extends Activity {
  protected static final int DOWNLOAD_ERROR = 1;
  private static final int THREAD_ERROR = 2;
  public static final int DWONLOAD_FINISH = 3;
  private EditText et_path;
  private EditText et_count;
  /**
   * 存放进度条的布局
   */
  private LinearLayout ll_container;
  
  /**
   * 进度条的集合
   */
  private List<ProgressBar> pbs;
  
  /**
   * android下的消息处理器,在主线程创建,才可以更新ui
   */
  private Handler handler = new Handler(){
    public void handleMessage(Message msg) {
      switch (msg.what) {
      case DOWNLOAD_ERROR:
        Toast.makeText(getApplicationContext(), "下载失败", 0).show();
        break;
      case THREAD_ERROR:
        Toast.makeText(getApplicationContext(), "下载失败,请重试", 0).show();
        break;
      case DWONLOAD_FINISH:
        Toast.makeText(getApplicationContext(), "下载完成", 0).show();
        break;
      }
    };
  };
  
  /**
   * 线程的数量
   */
  private int threadCount = 3;

  /**
   * 每个下载区块的大小
   */
  private long blocksize;

  /**
   * 正在运行的线程的数量
   */
  private  int runningThreadCount;


  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    et_path = (EditText) findViewById(R.id.et_path);
    et_count = (EditText) findViewById(R.id.et_count);
    ll_container = (LinearLayout) findViewById(R.id.ll_container);
  }

  /**
   * 下载按钮的点击事件
   * @param view
   */
  public void downLoad(View view){
    //下载文件的路径
    final String path = et_path.getText().toString().trim();
    if(TextUtils.isEmpty(path)){
      Toast.makeText(this, "对不起下载路径不能为空", 0).show();
      return;
    }
    String count = et_count.getText().toString().trim();
    if(TextUtils.isEmpty(path)){
      Toast.makeText(this, "对不起,线程数量不能为空", 0).show();
      return;
    }
    threadCount = Integer.parseInt(count);
    //清空掉旧的进度条
    ll_container.removeAllViews();
    //在界面里面添加count个进度条
    pbs = new ArrayList<ProgressBar>();
    for(int j=0;j<threadCount;j++){
      ProgressBar pb = (ProgressBar) View.inflate(this, R.layout.pb, null);
      ll_container.addView(pb);
      pbs.add(pb);
    }
    Toast.makeText(this, "开始下载", 0).show();
    new Thread(){
      public void run() {
        try {
          URL url = new URL(path);
          HttpURLConnection conn = (HttpURLConnection) url.openConnection();
          conn.setRequestMethod("GET");
          conn.setConnectTimeout(5000);
          int code = conn.getResponseCode();
          if (code == 200) {
            long size = conn.getContentLength();// 得到服务端返回的文件的大小
            System.out.println("服务器文件的大小:" + size);
            blocksize = size / threadCount;
            // 1.首先在本地创建一个大小跟服务器一模一样的空白文件。
            File file = new File(Environment.getExternalStorageDirectory(),getFileName(path));
            RandomAccessFile raf = new RandomAccessFile(file, "rw");
            raf.setLength(size);
            // 2.开启若干个子线程分别去下载对应的资源。
            runningThreadCount = threadCount;
            for (int i = 1; i <= threadCount; i++) {
              long startIndex = (i - 1) * blocksize;
              long endIndex = i * blocksize - 1;
              if (i == threadCount) {
                // 最后一个线程
                endIndex = size - 1;
              }
              System.out.println("开启线程:" + i + "下载的位置:" + startIndex + "~"
                  + endIndex);
              int threadSize = (int) (endIndex - startIndex);
              pbs.get(i-1).setMax(threadSize);
              new DownloadThread(path, i, startIndex, endIndex).start();
            }
          }
          conn.disconnect();
        } catch (Exception e) {
          e.printStackTrace();
          Message msg = Message.obtain();
          msg.what = DOWNLOAD_ERROR;
          handler.sendMessage(msg);
        }
        
      };
    }.start();
    
  }
  private class DownloadThread extends Thread {
    
    private int threadId;
    private long startIndex;
    private long endIndex;
    private String path;

    public DownloadThread(String path, int threadId, long startIndex,
        long endIndex) {
      this.path = path;
      this.threadId = threadId;
      this.startIndex = startIndex;
      this.endIndex = endIndex;
    }

    @Override
    public void run() {
      try {
        // 当前线程下载的总大小
        int total = 0;
        File positionFile = new File(Environment.getExternalStorageDirectory(),getFileName(path)+threadId + ".txt");
        URL url = new URL(path);
        HttpURLConnection conn = (HttpURLConnection) url
            .openConnection();
        conn.setRequestMethod("GET");
        // 接着从上一次的位置继续下载数据
        if (positionFile.exists() && positionFile.length() > 0) {// 判断是否有记录
          FileInputStream fis = new FileInputStream(positionFile);
          BufferedReader br = new BufferedReader(
              new InputStreamReader(fis));
          // 获取当前线程上次下载的总大小是多少
          String lasttotalstr = br.readLine();
          int lastTotal = Integer.valueOf(lasttotalstr);
          System.out.println("上次线程" + threadId + "下载的总大小:"
              + lastTotal);
          startIndex += lastTotal;
          total += lastTotal;// 加上上次下载的总大小。
          fis.close();
          //存数据库。
          //_id path threadid total
        }

        conn.setRequestProperty("Range", "bytes=" + startIndex + "-"
            + endIndex);
      
        conn.setConnectTimeout(5000);
        int code = conn.getResponseCode();
        System.out.println("code=" + code);
        InputStream is = conn.getInputStream();
        File file = new File(Environment.getExternalStorageDirectory(),getFileName(path));
        RandomAccessFile raf = new RandomAccessFile(file, "rw");
        // 指定文件开始写的位置。
        raf.seek(startIndex);
        System.out.println("第" + threadId + "个线程:写文件的开始位置:"
            + String.valueOf(startIndex));
        int len = 0;
        byte[] buffer = new byte[1024];
        while ((len = is.read(buffer)) != -1) {
          RandomAccessFile rf = new RandomAccessFile(positionFile,
              "rwd");
          raf.write(buffer, 0, len);
          total += len;
          rf.write(String.valueOf(total).getBytes());
          rf.close();
          pbs.get(threadId-1).setProgress(total);
        }
        is.close();
        raf.close();

      } catch (Exception e) {
        e.printStackTrace();
        Message msg = Message.obtain();
        msg.what = THREAD_ERROR;
        handler.sendMessage(msg);
      } finally {
        // 只有所有的线程都下载完毕后 才可以删除记录文件。
        synchronized (MainActivity.class) {
          System.out.println("线程" + threadId + "下载完毕了");
          runningThreadCount--;
          if (runningThreadCount < 1) {
            System.out.println("所有的线程都工作完毕了。删除临时记录的文件");
            for (int i = 1; i <= threadCount; i++) {
              File f = new File(Environment.getExternalStorageDirectory(),getFileName(path)+ i + ".txt");
              System.out.println(f.delete());
            }
            Message msg = Message.obtain();
            msg.what = DWONLOAD_FINISH;
            handler.sendMessage(msg);
          }
        }

      }
    }
  }
  //http://192.168.1.100:8080/aa.exe
  private String getFileName(String path){
    int start = path.lastIndexOf("/")+1;
    return path.substring(start);
  }
  
}

利用XUtils开源框架实现,需要XUtils的jar包

public class MainActivity extends Activity {
  private EditText et_path;
  private TextView tv_info;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    et_path = (EditText) findViewById(R.id.et_path);
    tv_info = (TextView) findViewById(R.id.tv_info);
  }

  public void download(View view){
    String path = et_path.getText().toString().trim();
    if(TextUtils.isEmpty(path)){
      Toast.makeText(this, "请输入下载的路径", 0).show();
      return;
    }else{
      HttpUtils http = new HttpUtils();
      HttpHandler handler = http.download(path,
          "/sdcard/xxx.zip",
            true, // 如果目标文件存在,接着未完成的部分继续下载。服务器不支持RANGE时将从新下载。
            true, // 如果从请求返回信息中获取到文件名,下载完成后自动重命名。
            new RequestCallBack<File>() {

                @Override
                public void onStart() {
                  tv_info.setText("conn...");
                }

                @Override
                public void onLoading(long total, long current, boolean isUploading) {
                  tv_info.setText(current + "/" + total);
                }

                @Override
                public void onSuccess(ResponseInfo<File> responseInfo) {
                  tv_info.setText("downloaded:" + responseInfo.result.getPath());
                }
                @Override
                public void onFailure(HttpException error, String msg) {
                  tv_info.setText(msg);
                }
        });
    }
  }
}

完成