android handler msg的使用 实现进度条

package com.app.threadtest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;

public class MyActivity extends Activity {
	//private static final int PROGRESS = 0x1;

	private ProgressBar mProgress;
	private Button mButton;
	private int mProgressStatus = 0;

	private Handler mHandler = new Handler();
	
	protected void onCreate(Bundle icicle) {
		super.onCreate(icicle);

		setContentView(R.layout.progressbar_activity);
		mProgress = (ProgressBar) findViewById(R.id.progress_bar);
		
		// 按钮事件
		mButton = (Button) findViewById(R.id.button1);
		mButton.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				
				// Start lengthy operation in a background thread
				new Thread(new Runnable() {
					public void run() {
						while (mProgressStatus < 100) {
							mProgressStatus = doWork();

							// Update the progress bar
							mHandler.post(new Runnable() {
								public void run() {
									mProgress.setProgress(mProgressStatus);
								}
							});
						}
					}
				}).start();
			}
		});
	}
	protected int doWork() {
		mProgressStatus++;
		return mProgressStatus;
	}
}