Android中线程和进度条的使用

当涉及到耗时的任务时，要用到进度条提示，也就是工作者线程和UI主线程的交互问题。

Andriod提供了几种在其他线程中访问UI线程的方法。

• Activity.runOnUiThread( Runnable )
• View.post( Runnable )
• View.postDelayed( Runnable, long )
• Hanlder
• 下面给出两个例子分别用handler和runOnUiThread访问UI主线程。

1、使用handler，普通进度条控件

TextView tvShowMessage;
Message message=null;   
Handler handler = new Handler()
{
     public void handleMessage(Message msg) { 
            switch (msg.what) {     
            case 1: 
                tvShowMessage.setText("步骤一");                        
                break;
            case 2:
                tvShowMessage.setText("步骤二");
                break;
            case 3:                  
                 tvShowMessage.setText("步骤三");
                break;

            }     
            super.handleMessage(msg); 
        } 
};

  class myThread implements Runnable {   
          public void run() {  
               message = new Message();     
              message.what = 1;     
              handler.sendMessage(message);             
  
              try {
                  Thread.sleep(500);
            } catch (InterruptedException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            message = new Message();     
            message.what = 2;     
            handler.sendMessage(message);
              try {
                  Thread.sleep(500);
            } catch (InterruptedException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

message = new Message();     
            message.what = 3;     
            handler.sendMessage(message);

}

}

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Request for the progress bar to be shown in the title
        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
        setContentView(R.layout.main);
        tvShowMessage=(TextView)findViewById(R.id.tvShowMessage);
        setProgressBarVisibility(true);     // Make sure the progress bar is visible
        new Thread(new myThread()).start();//启动线程  
    }

2、进度条对话框

    private ProgressDialog m_ProgressDialog = null;
    private Runnable viewOrders;

try
{
     //用线程启动进度条
       viewOrders = new Runnable(){
           @Override
           public void run() {
               dosomething();
           }
       };
       Thread thread =  new Thread(null, viewOrders, "Background");
       thread.start();
       m_ProgressDialog = ProgressDialog.show(CarSourceAdd.this,   
             "加载中", "请稍等...", true);
}
catch(Exception e)
{
     //。。。
}

 

    private void dosomething()
    {
          try {
       //耗时工作。。。

        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }    
      runOnUiThread(returnRes);
    }
    private Runnable returnRes = new Runnable() {
        @Override
        public void run() {
            m_ProgressDialog.dismiss();
            //执行成功后。。。
        }
    };