定義一個Service
例如AudioService 繼承自android.app.Service

AudioService.java

package com.outsider.service;

import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.IBinder;

public class AudioService extends Service {

    private
 
 MediaPlayer mp;
    private String query;

    @Override
    public void onCreate() {
        System.out.println("初始化音樂資源  ");
        super.onCreate();
    }

    @Override
    public void onStart(Intent intent, int startId) {
        if (query != null && !query.equals(intent.getStringExtra("query"
 
)) && mp != null) {
            mp.start();
        } else {
            String query = intent.getStringExtra("query");
            // System.out.println("http://dict.youdao.com/dictvoice?audio=" + query);
            Uri location = Uri.parse("http://dict.youdao.com/dictvoice?audio=" + query);

            mp = MediaPlayer.create(this
 
, location);
            // System.out.println("音樂開始播放");
            mp.start();

            // 音樂播放完畢的事件處理
            mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                public void onCompletion(MediaPlayer mp) {
                    // 不迴圈播放
                    try {
                        // mp.start();
                        System.out.println("stopped");
                    } catch (IllegalStateException e) {
                        e.printStackTrace();
                    }
                }
            });

            // 播放音樂時發生錯誤的事件處理
            mp.setOnErrorListener(new MediaPlayer.OnErrorListener() {
                public boolean onError(MediaPlayer mp, int what, int extra) {
                    // 釋放資源
                    try {
                        mp.release();
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                    return false;
                }
            });
        }

        // super.onStart(intent, startId);
    }

    @Override
    public void onDestroy() {
        // 服務停止時停止播放音樂並釋放資源
        mp.stop();
        mp.release();
        super.onDestroy();
    }

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

如何啟動一個Service

Intent intent = new Intent(MainActivity.this, AudioService.class);
intent.putExtra("query", english.getText());
startService(intent);