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;      }    }  };}