Android消息机制之Message类等与AsyncTask类分别处理进度条

两种方式各有不同，AsyncTask类从操作上更简单并且容易实现，而用第一种方法则要用到4个类：Handler, Message, Looper, Thread类，原因是进度条这种耗时的操作一般要放入子线程处理，而子线程无权改动UI线程的任何组件，只能动过Handler类传递Message来改动

　Activity组件准备：

public class MainActivity extends Activity {
    
    private ProgressBar progressBar1 = null;
    private TextView progressBar1Text = null;
    private ProgressBar progressBar2 = null;
    private TextView progressBar2Text = null;
    private Button startBtn = null;
    private MyHandler myHandler = null;
    
    private static final int SETPROGRESS = 1;
    private static final int FINISH = 2;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        progressBar1 = (ProgressBar) findViewById(R.id.progressBar1);
        progressBar1Text = (TextView) findViewById(R.id.progressBar1Text);
        progressBar2 = (ProgressBar) findViewById(R.id.progressBar2);
        progressBar2Text = (TextView) findViewById(R.id.progressBar2Text);
        myHandler = new MyHandler();
        
        startBtn = (Button) findViewById(R.id.startBtn);
        startBtn.setOnClickListener(new StartBtnListener());
        
    }

开始按钮监听：

    private class StartBtnListener implements OnClickListener {

        @Override
        public void onClick(View v) {
            // 异步处理进度条
            MyAsyncTask mat = new MyAsyncTask();
            mat.execute(100);
            
            // handler + message 处理进度条
            new Thread(new MyThread()).start();
        }
        
    }

异步处理类：

AsyncTask<Integer, Integer, String>

第一参数：传入的延时参数； 第二参数：即时进度 ；第三参数：任务结束后的返回值

    // 使用异步处理工具类完成更新进度条
    private class MyAsyncTask extends AsyncTask<Integer, Integer, String> {
        
        @Override
        protected void onPostExecute(String result) {
            MainActivity.this.progressBar1Text.setText(result);    
        }

        @Override
        protected void onProgressUpdate(Integer... values) {
            MainActivity.this.progressBar1Text.setText("进度: " + values[0]);
        }

        @Override
        protected String doInBackground(Integer... params) {
            for (int i = 0; i < MainActivity.this.progressBar1.getMax(); i++) {
                MainActivity.this.progressBar1.setProgress(i);
                // 更新操作,传给onProgressUpdate方法
                this.publishProgress(i);
                try {
                    Thread.sleep(params[0]);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } 
            
            // 传给onPostExecute方法
            return "执行完毕哦";
        }
        
    }