ImageView的使用（android）

在 android 中显示图片使用的是 ImageView ，这里的代码是从书中的例子来的，使用很简单，现在才觉得 android开发真的好方便呀

代码如下：

xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <ImageView 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/image1"
        />

</LinearLayout>

java代码

package zziss.android.imagetest;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ImageView;

public class ImageTestActivity extends Activity {
    /** Called when the activity is first created. */
    private ImageView iv;
    private int img_alpha = 0;
    Handler  iHandler = new Handler();
    private boolean iIsRun = false;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        iv = (ImageView)this.findViewById(R.id.image1);
        iv.setImageResource(R.drawable.q2);
        iv.setAlpha(img_alpha);
        iIsRun = true;
        
        new Thread(new Runnable()
        {

            @Override
            public void run() {
                // TODO Auto-generated method stub
                while (iIsRun)
                {
                    try
                    {
                        Thread.sleep(200);
                        updateAlpha();
                    }
                    catch(InterruptedException e)
                    {
                        e.printStackTrace();
                    }
                }
            }
            
        } // end new runnable
                ).start();// end new thread
        
        iHandler = new Handler()
        {

            @Override
            public void handleMessage(Message msg) {
                // TODO Auto-generated method stub
                super.handleMessage(msg);
                iv.setAlpha(img_alpha);
                iv.invalidate();
            }
            
            
        };
        
    }
    
    private void updateAlpha()
    {
        if (img_alpha+7<=255)
        {
            img_alpha+=7;
        }else
        {
            img_alpha = 255;
            iIsRun = false;
        }
        iHandler.sendMessage(iHandler.obtainMessage());
    }
}