Android 按键式事件

package com.fish.helloworld;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

    private ImageView m_ImageView;
    private TextView m_TextView;
    private float m_AlphaValue;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test_key);
        
        m_ImageView = (ImageView)findViewById(R.id.imageView1);
        m_TextView = (TextView)findViewById(R.id.textView1);
        m_AlphaValue = 0xFF;
        
        m_ImageView.setAlpha(m_AlphaValue);
        m_TextView.setText("Alpha = " + m_AlphaValue * 100 / 0xff + "%");
    }
    
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent msg){
        
        Log.v("KeyCode","KeyCode = " + keyCode);
        Log.v("msg","msg = " + msg);
        
        switch(keyCode){
        case KeyEvent.KEYCODE_VOLUME_UP:
            m_AlphaValue += 20;
            break;
        case KeyEvent.KEYCODE_VOLUME_DOWN:
            m_AlphaValue -= 20;
            break;
            default:
                break;
        
        }
        
        if(m_AlphaValue >= 0xFF) m_AlphaValue = 0xFF;
        if(m_AlphaValue <= 0x00) m_AlphaValue = 0x0;
        
        m_ImageView.setAlpha(m_AlphaValue);
        m_TextView.setText("Alpha = " + m_AlphaValue * 100 / 0xff + "%");
        
        return super.onKeyDown(keyCode, msg);
    }
}

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

    <TextView
        android:id="@+id/textView1"
        android:layout_width="110dp"
        android:layout_height="wrap_content"
        android:layout_weight="0.03"
        android:text="TextView" />

    <ImageView
        android:id="@+id/imageView1"
        android:layout_width="241dp"
        android:layout_height="195dp"
        android:layout_marginRight="37dp"
        android:layout_marginTop="176dp"
        android:layout_weight="0.06"
        android:src="@drawable/ic_launcher" />

</LinearLayout>

package com.fish.helloworld;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {

    private TextView m_TextView;
    private TextView m_TextView2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.skeleton_activity);
        
        m_TextView = (TextView)findViewById(R.id.textView1);
        m_TextView2 = (TextView)findViewById(R.id.textView2);
        
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event){
        
        int action = event.getAction();
        float x = event.getX();
        float y = event.getY();
        
        m_TextView.setText("Action = " + action);
        m_TextView2.setText(x + " + " + y);
        
        return true;
    }
    
}