android中设立按钮不同状态时按钮的效果

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package cn.edu.button;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;import android.view.View;import android.view.View.OnClickListener;import android.view.View.OnKeyListener;import android.widget.Button;public class ButtonActivity extends Activity {    /** Called when the activity is first created. */	private	Button btn;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        btn=(Button)this.findViewById(R.id.btn);        btn.setOnClickListener(new OnClickListener(){			@Override			public void onClick(View arg0) {				// TODO Auto-generated method stub				System.out.println("btn pressed");			}        	        });    }}

?在res文件夹下，新建drawable文件夹，同时，新建ic_tab_artists.xml文件

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?xml version="1.0" encoding="utf-8"?><selector xmlns:android="http://schemas.android.com/apk/res/android">    <item android:drawable="@drawable/android_pressed"          android:state_pressed="true" />    <item android:drawable="@drawable/android_focused"          android:state_focused="true" />    <item android:drawable="@drawable/android_normal" /></selector>

在布局文件中

    <ImageButton     	android:layout_width="fill_parent"     	android:layout_height="wrap_content"    	android:background="@drawable/ic_tab_artists"    />
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