package com.lxt008;import com.lxt008.R;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.widget.ImageView;import android.widget.TextView;public class Activity01 extends Activity{    //声明ImageView对象    ImageView    imageview;    TextView    textview;    //ImageView的alpha值，    int            image_alpha    = 255;    Handler        mHandler    = new Handler();    //控件线程    boolean        isrung        = false;    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState)    {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        isrung        = true;                //获得ImageView的对象        imageview = (ImageView) this.findViewById(R.id.ImageView01);        textview = (TextView) this.findViewById(R.id.TextView01);                //设置imageview的图片资源。同样可以再xml布局中像下面这样写        //android:src="http://www.mamicode.com/@drawable/logo"        imageview.setImageResource(R.drawable.logo);                //设置imageview的Alpha值        imageview.setAlpha(image_alpha);        //开启一个线程来让Alpha值递减        new Thread(new Runnable() {            public void run()            {                while (isrung)                {                    try                    {                        Thread.sleep(200);                        //更新Alpha值                        updateAlpha();                    }                    catch (InterruptedException e)                    {                        e.printStackTrace();                    }                }            }        }).start();        //接受消息之后更新imageview视图        mHandler = new Handler() {            @Override            public void handleMessage(Message msg)            {                super.handleMessage(msg);                imageview.setAlpha(image_alpha);                textview.setText("现在alpha值是："+Integer.toString(image_alpha));                //更新                imageview.invalidate();            }        };    }        public void updateAlpha()    {        if (image_alpha - 7 >= 0)        {            image_alpha -= 7;        }        else        {            image_alpha = 0;            isrung = false;        }        //发送需要更新imageview视图的消息        mHandler.sendMessage(mHandler.obtainMessage());    }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout    xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><ImageView    android:id="@+id/ImageView01"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    ></ImageView><TextView    android:id="@+id/TextView01"    android:layout_below="@id/ImageView01"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    ></TextView></LinearLayout>