Android開發之ProgressDialog在獨立Thread線程中更新進度

簡單的需求：在一個工作Thread中更新進度對話框ProgressDialog

遇到的問題：

1，創建需要Context，這個需要傳進來

2，Thread中不能創建ProgressDialog，否則需要創建Looper

3，直接在Thread中更新ProgressDialog不行，扔例外，不是創建Thread的View不允許更新

4，Thread外創建Handler，然后現成里Post，更本不會更新。

解決方案：

1，創建ProgressDialog，同時創建Handler，用Callback handleMessage更新對話框

2，Thread中調用sendMessage之后，還需要調用Thread.yield()或Thread.sleep(),否則同樣不更新。

示例代碼：

    final ProgressDialog pgDlg=new ProgressDialog(mContext);
    pgDlg.setTitle("Testing ...");pgDlg.setMessage(" ");
    pgDlg.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    pgDlg.setIndeterminate(false);    pgDlg.setMax(100);pgDlg.setProgress(0);
    pgDlg.setIcon(android.R.drawable.ic_menu_search);
    final  Handler dlgHandler=new Handler(new Handler.Callback() {
      @Override
      public boolean handleMessage(Message msg) {
        String s = (String)msg.obj;
        pgDlg.setMessage(s);
        if(msg.what>=100){
          pgDlg.setProgress(100);
          new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
              pgDlg.dismiss();
            }
          },1000);
        }else{
          pgDlg.setProgress(msg.what);
        }
        return true;
      }
    });
    pgDlg.show();
    new Thread(new Runnable() {
      @Override
      public void run() {
        BluetoothGattCharacteristic ctc=bleHelper.getCharacteristic(SampleGattAttributes.SERVICE_KeyService,SampleGattAttributes.CHARACTERISTIC_KeyCharacteristic);
        for (int i=0;i<cmdsToTest.length;i++){
          String cmd = cmdsToTest[i];
          final String msg=String.format("command>：%s", cmd);
          AppUtils.logD(msg);
          ObdCommand oc = new ObdCommand(cmd, cmd);
          final ObdCommandJob job = new ObdCommandJob(oc);
          CommandExecutor executor = new BleCommandExecutor(bleHelper,ctc, job) .setLocker(mJobLock, mJobCondition);
          try {
            mJobLock.lock();
            new Thread(executor).start();
            mJobCondition.await(5, TimeUnit.SECONDS);
          } catch (InterruptedException ex) {
            Log.e("", ex.getMessage());
            job.setState(ObdCommandJobState.EXECUTION_ERROR);
          } finally {
            mJobLock.unlock();
            bleHelper.resumeIO();
          }
          if (job.getState() != ObdCommandJobState.FINISHED) {
            errorMsg = String.format("test command %s failed!", job.getCommand().getCommand());
            if (resultListener != null) {
              resultListener.onTestDone(false, errorMsg);
              Message.obtain(dlgHandler,100,errorMsg).sendToTarget(); Thread.yield();
　　　　　　　　break;
            }
          }
          final int progress = i*100/cmdsToTest.length;
          Message.obtain(dlgHandler,progress,msg+"\nresult>:"+job.getCommand().getRawData()).sendToTarget();
          //pgDlg.setMessage(msg);  throw exception when access direct here
          //pgDlg.incrementProgressBy(progress );
          Thread.yield();//must yield to let message processed
        }
        if (resultListener != null) {
          resultListener.onTestDone(true, "");
          Message.obtain(dlgHandler,100,"done").sendToTarget(); Thread.yield();
        }
        bleHelper.close();
      }
    }).start();