一. 按钮音 

int nNotifCationVol = 0;
try{
    nNotifCationVol = Settings.System.getInt(getContentResolver(),Settings.System.SOUND_EFFECTS_ENABLED);
}catch(SettingNotFoundException e){
    e.printStackTrace();
}

二. 系统音量
1. 取系统音量

AudioManager am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
int nMaxVol = am.getStreamMaxVolume(AudioManager.STREAM_SYSTEM);
int nCurVol = am.getStreamVolume(AudioManager.STREAM_SYSTEM);

2. 设置系统音量

AudioManager am = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
am.setStreamVolume(AudioManager.STREAM_SYSTEM, nVolume, 0);

注意：设置系统音量时要先设置权限，否则程序会崩溃，即在AndroidManifest.xml中添加一句<uses-permission android:name="android.permission.WRITE_SETTINGS" />如下所示：

​​​​​​​<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="www.llxxhm.com"
      android:versionCode="1"
      android:versionName="1.0">
 <uses-permission android:name="android.permission.WRITE_SETTINGS" />
  
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".main"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name="serve" ></activity>
        <activity android:name="travel" ></activity>
        <activity android:name="setting" ></activity>
        <activity android:name="volume" ></activity>
    </application>
    <uses-sdk android:minSdkVersion="8" />
</manifest> 

改通话音量只要把AudioManager.STREAM_SYSTEM改为AudioManager.STREAM_VOICE_CALL就行了