Android 四大组件之 Service_3_音乐播放器(本地Service)

一、 基本介绍

简单的音乐播放器实例， 提供播放、停止、暂停、退出音乐操作。 先由Activity 实现，再引出由Service(本地Service)实现。

二、Acitivity实现

1. 布局文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Play"
        android:onClick="playMusic"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Stop"
        android:onClick="stopMusic"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Pause"
        android:onClick="pauseMusic"/>
    <Button
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:text="Exit"
        android:onClick="exitMusic"/>

</LinearLayout>

2. Activity中实现音乐操作

package com.example.musicplayer;

import androidx.appcompat.app.AppCompatActivity;

import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {
    private static final String TAG = "MainActivity";
    private MediaPlayer mPlayer = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void playMusic(View view) {
        log("playMusic");
        if (mPlayer == null) {
            mPlayer = MediaPlayer.create(this, R.raw.simple_music);
        }
        mPlayer.start();
        log("playMusic done");
    }

    public void stopMusic(View view) {
        log("stopMusic");
        if (mPlayer != null) {
            mPlayer.stop();
            mPlayer.reset(); //重置(进度)
            mPlayer.release(); //释放资源
            mPlayer = null;
            log("stopMusic done");
        }
    }