Android開發之通過Handler的post方法更新UI

在Android中可以通過handler方法完成資料的線程間的傳遞，但一定要將handler得到的資料通過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方法是在主線程啟動並執行，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();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);imageView=(ImageView)this.findViewById(R.id.imageView1);new MyThread().start();}@Overridepublic 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;@Overridepublic 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 blocke.printStackTrace();}} catch (MalformedURLException e) {// TODO Auto-generated catch blocke.printStackTrace();}    Runnable runnable=new Runnable() {@Overridepublic void run() {// TODO Auto-generated method stubBitmap bm=BitmapFactory.decodeByteArray(data, 0,data.length );imageView.setImageBitmap(bm);}};myhandler.post(runnable);}}}