Android实现音量调节的方法

<?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">
  <button android:id="@+id/btnplay" 
    android:layout_width="fill_parent"
    android:layout_height="wrap_content" 
    android:text="播放音乐" />
  <linearlayout android:orientation="horizontal"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal">
    <togglebutton android:id="@+id/tbmute"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content" 
      android:texton="静音"
      android:textoff="正常"
      android:checked="true"
      android:layout_gravity="center_vertical" />
    <button android:id="@+id/btnupper"
      android:text="增大音量" 
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
    <button android:id="@+id/btnlower"
      android:text="减小音量" 
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
  </linearlayout>
</linearlayout>

package com.ljq.activity;
import android.app.activity;
import android.app.service;
import android.media.audiomanager;
import android.media.mediaplayer;
import android.os.bundle;
import android.view.view;
import android.widget.button;
import android.widget.compoundbutton;
import android.widget.togglebutton;
import android.widget.compoundbutton.oncheckedchangelistener;
public class audioactivity extends activity {
  private button btnplay=null, btnupper=null, btnlower=null;
  private togglebutton tbmute=null;
  private mediaplayer mediaplayer=null; //声频
  private audiomanager audiomanager=null; //音频
  @override
  public void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.main);
    audiomanager=(audiomanager)getsystemservice(service.audio_service);
    btnplay=(button)findviewbyid(r.id.btnplay);
    btnupper=(button)findviewbyid(r.id.btnupper);
    btnlower=(button)findviewbyid(r.id.btnlower);
    btnplay.setonclicklistener(listener);
    btnupper.setonclicklistener(listener);
    btnlower.setonclicklistener(listener);
    tbmute=(togglebutton)findviewbyid(r.id.tbmute);
    tbmute.setoncheckedchangelistener(new oncheckedchangelistener(){
      public void oncheckedchanged(compoundbutton buttonview, boolean ischecked) {
        audiomanager.setstreammute(audiomanager.stream_music, !ischecked); //设置是否静音
      }
    });
  }
  view.onclicklistener listener=new view.onclicklistener(){
    public void onclick(view v) {
      @suppresswarnings("unused")
      button btn=(button)v;
      switch (v.getid()) {
      case r.id.btnplay://播放音乐
        mediaplayer=mediaplayer.create(audioactivity.this, r.raw.music);
        mediaplayer.setlooping(true);//设置循环播放
        mediaplayer.start();//播放声音  
        break;
      case r.id.btnupper://增多音量
        //adjuststreamvolume: 调整指定声音类型的音量
        audiomanager.adjuststreamvolume(audiomanager.stream_music, 
            audiomanager.adjust_raise, 
            audiomanager.flag_show_ui);  //调高声音
        break;
      case r.id.btnlower://减少音量
        //第一个参数：声音类型
        //第二个参数：调整音量的方向
        //第三个参数：可选的标志位
        audiomanager.adjuststreamvolume(audiomanager.stream_music, 
            audiomanager.adjust_lower, 
            audiomanager.flag_show_ui);//调低声音
        break;
      }
    }
  };
}