通過AudioManager的adjustVolume()方法調節音量

通過AudioManager的adjustVolume()方法調節音量: 調節最相關聲源(stream)的音量. 例如, 如果正在通話中, 話音音量的優先權最高. 一個呼叫處於活動狀態，這將有最高的優先權，不論是否在通話屏幕顯示. 又例如, 如果不是在通話中, 而後台正在播放音樂, 音樂的音量將被調整.

main.xml

<?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"
 >
<TextView
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="@string/hello"
 />
<Button
 android:id="@+id/volup"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="VOL +"
 />
<Button
 android:id="@+id/voldown"
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:text="VOL -"
 />
</LinearLayout>

AndroidVolume.java

package com.AndroidVolume;

import android.app.Activity;
import android.content.Context;
import android.media.AudioManager;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class AndroidVolume extends Activity {
 
 AudioManager audioManager;
 
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     Button buttonVolUp = (Button)findViewById(R.id.volup);
     Button buttonVolDown = (Button)findViewById(R.id.voldown);
  
     audioManager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
  
     buttonVolUp.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    audioManager.adjustVolume(AudioManager.ADJUST_RAISE, 0);
   }});
  
     buttonVolDown.setOnClickListener(new Button.OnClickListener(){

   @Override
   public void onClick(View arg0) {
    // TODO Auto-generated method stub
    audioManager.adjustVolume(AudioManager.ADJUST_LOWER, 0);
   }});
  
 }
}