Android開發之通過Handler的post方法更新UI

在Android中可以通過handler方法完成數據的線程間的傳遞，但一定要將handler得到的數據通過loop傳遞到主線程再更新UI嗎？其實也可以直接使用handler設計的post方法進行實現，handler的post方法是在主線程運行的，可以直接進行UI的更新操作。

MainActivity的代碼

package com.example.e15_handler_post;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;
import android.view.Menu;
import android.widget.ImageView;

public class MainActivity extends Activity {
    private ImageView imageView;
    private Handler myhandler=new Handler();
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		imageView=(ImageView)this.findViewById(R.id.imageView1);
		new MyThread().start();
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}
	
	public class MyThread extends Thread{
		byte[] data=new byte[1024];
		int len=0;
		@Override
		public void run() {
			// TODO Auto-generated method stub
		    try {
				URL url=new URL("http://111.0.229.223:8080/http/hangzhou.jpg");
				try {
					HttpURLConnection connection=(HttpURLConnection) url.openConnection();
					InputStream inputStream=connection.getInputStream();
					ByteArrayOutputStream arrayOutputStream=new ByteArrayOutputStream();
					while((len=inputStream.read(data))!=-1){
						
					   arrayOutputStream.write(data, 0, len);
						
					}
					data=arrayOutputStream.toByteArray();
					Log.i("info", "------->"+data.length);
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				
			} catch (MalformedURLException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		    
			Runnable runnable=new Runnable() {
				
				@Override
				public void run() {
					// TODO Auto-generated method stub
					Bitmap bm=BitmapFactory.decodeByteArray(data, 0,data.length );
					imageView.setImageBitmap(bm);
				}
			};
			myhandler.post(runnable);
		}
	}

}