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2021-05-11

作者:互联网

安卓开发之音乐盒

1.首先注册BroadcastReceiver

在AndroidManifest中的application标签下添加receiver子标签
//生成的receiver配置文件

         <receiver
             android:name=".MyReceiver"
             android:enabled="true"
             android:exported="true">
             <intent-filter>
             //自定义Action
                 <action android:name="MLY" />
             </intent-filter>
         </receiver>

2.在AndroidManifest.xml里配置service

<service
    android:name=".MusicService"
    android:enabled="true"
    android:exported="true"></service>

3.创建一个assests文件,将歌曲放进文件里

4.在布局文件中,放入两个Textview控件以显示歌曲信息和四个ImageButton控件以实现相应功能

activity_main.xml文件代码:

<?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="180dp"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="32dp"
        android:layout_weight="1"
        android:gravity="center"
        android:text="歌曲"
        android:textSize="20dp"
        android:textColor="#9C27B0"
        android:ellipsize="marquee"
        android:marqueeRepeatLimit="marquee_forever"/> />

    <TextView
        android:id="@+id/author"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="演唱者"
        android:textSize="20dp" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="90dp"
        android:orientation="horizontal">

        <ImageButton
            android:id="@+id/front"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/front" />

        <ImageButton
            android:id="@+id/play"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/play" />

        <ImageButton
            android:id="@+id/stop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/stop" />

        <ImageButton
            android:id="@+id/next"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/next" />

    </LinearLayout>

</LinearLayout>

5.编写Java文件

MainActivity.java中的代码:

package com.example.musicbox;

import java.io.IOException;

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.res.AssetFileDescriptor;
import android.content.res.AssetManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.os.IBinder;

public class MusicService extends Service {
    MyReceiver serviceReceiver;
    AssetManager am;
    String[] musics = new String[] { "wish.mp3", "promise.mp3", "beautiful.mp3" };
    MediaPlayer mPlayer;
    // 当前的状态,0x11代表没有播放;0x12代表正在播放;0x13代表暂停
    int status = 0x11;
    // 记录当前正在播放的音乐
    int current = 0;
    @Override
    public IBinder onBind(Intent intent) { return null; }
    @Override
    public void onCreate() {
        super.onCreate();
        am = getAssets();
        // 创建BroadcastReceiver
        serviceReceiver = new MyReceiver();
        // 创建IntentFilter
        IntentFilter filter = new IntentFilter();
        filter.addAction(MainActivity.CTL_ACTION);
        registerReceiver(serviceReceiver, filter);
        // 创建MediaPlayer
        mPlayer = new MediaPlayer();
        // 为MediaPlayer播放完成事件绑定监听器
        mPlayer.setOnCompletionListener(new OnCompletionListener() // ①
        {
            @Override
            public void onCompletion(MediaPlayer mp)
            {
                current++;
                if (current >= 3)
                {
                    current = 0;
                }
                //发送广播通知Activity更改文本框
                Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
                sendIntent.putExtra("current", current);
                // 发送广播,将被Activity组件中的BroadcastReceiver接收到
                sendBroadcast(sendIntent);
                // 准备并播放音乐
                prepareAndPlay(musics[current]);
            }
        });
    }
    public class MyReceiver extends BroadcastReceiver {
        @Override
        public void onReceive(final Context context, Intent intent) {
            int control = intent.getIntExtra("control", -1);
            switch (control)
            {
                // 播放或暂停
                case 1:
                    // 原来处于没有播放状态
                    if (status == 0x11)
                    {
                        // 准备并播放音乐
                        prepareAndPlay(musics[current]);
                        status = 0x12;
                    }
                    // 原来处于播放状态
                    else if (status == 0x12)
                    {
                        // 暂停
                        mPlayer.pause();
                        // 改变为暂停状态
                        status = 0x13;
                    }
                    // 原来处于暂停状态
                    else if (status == 0x13)
                    {
                        // 播放
                        mPlayer.start();
                        // 改变状态
                        status = 0x12;
                    }
                    break;
                // 停止声音
                case 2:
                    // 如果原来正在播放或暂停
                    if (status == 0x12 || status == 0x13)
                    {
                        // 停止播放
                        mPlayer.stop();
                        status = 0x11;
                    }
            }
            // 广播通知Activity更改图标、文本框
            Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
            sendIntent.putExtra("update", status);
            sendIntent.putExtra("current", current);
            // 发送广播,将被Activity组件中的BroadcastReceiver接收到
            sendBroadcast(sendIntent);
        }
    }
    private void prepareAndPlay(String music) {
        try {
            // 打开指定音乐文件
            AssetFileDescriptor afd = am.openFd(music);
            mPlayer.reset();
            // 使用MediaPlayer加载指定的声音文件。
            mPlayer.setDataSource(afd.getFileDescriptor(),
                    afd.getStartOffset(), afd.getLength());
            // 准备声音
            mPlayer.prepare();
            // 播放
            mPlayer.start();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

onCreate()函数
用于获取相应按钮以及添加监听器、注册receiver

public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // 获取程序界面界面中的四个按钮
    front=(ImageButton)this.findViewById(R.id.front);
    play = (ImageButton) this.findViewById(R.id.play);
    stop = (ImageButton) this.findViewById(R.id.stop);
    next=(ImageButton)this.findViewById(R.id.next);

    title = (TextView) findViewById(R.id.title);
    author = (TextView) findViewById(R.id.author);

    // 为四个按钮的单击事件添加监听器
    play.setOnClickListener(this);
    stop.setOnClickListener(this);
    front.setOnClickListener(this);
    next.setOnClickListener(this);

    activityReceiver = new ActivityReceiver();
    // 创建IntentFilter
    IntentFilter filter = new IntentFilter();
    // 指定BroadcastReceiver监听的Action
    filter.addAction(UPDATE_ACTION);
    // 注册BroadcastReceiver
    registerReceiver(activityReceiver, filter);

    Intent intent = new Intent(this, MusicService.class);
    // 启动后台Service
    startService(intent);
}

ActivityReceiver子类,负责监听从Service传回来的广播,并用switch控制系统状态,且定义了在音乐播放的不同状态下显示的图片

public class ActivityReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent)
    {
        // 获取Intent中的update消息,update代表播放状态
        int update = intent.getIntExtra("update", -1);
        // 获取Intent中的current消息,current代表当前正在播放的歌曲
        int current = intent.getIntExtra("current", -1);
        if (current >= 0)
        {
            title.setText(titleStrs[current]);
            author.setText(authorStrs[current]);
        }


        switch (update)
        {
            case 0x11:
                play.setImageResource(R.drawable.play);
                status = 0x11;
                break;
            // 控制系统进入播放状态
            case 0x12:
                // 播放状态下设置使用暂停图标
                play.setImageResource(R.drawable.pause);
                // 设置当前状态
                status = 0x12;
                break;
            // 控制系统进入暂停状态
            case 0x13:
                // 暂停状态下设置使用播放图标
                play.setImageResource(R.drawable.play);
                // 设置当前状态
                status = 0x13;
                break;
        }
    }
}

onClick函数,用switch判断点击事件,向Service发送广播

public void onClick(View source)
    {
        // 创建Intent
        Intent intent = new Intent("org.xr.action.CTL_ACTION");
        switch (source.getId())
        {
            // 按下播放/暂停按钮
            case R.id.play:
                intent.putExtra("control", 1);
                break;
            // 按下停止按钮
            case R.id.stop:
                intent.putExtra("control", 2);
                break;
            case R.id.front:
                intent.putExtra("control",3);
                break;
            //按下下一首
            case R.id.next:
                intent.putExtra("control",4);
                break;
        }
        // 发送广播,将被Service组件中的BroadcastReceiver接收到
        sendBroadcast(intent);
    }
}

MusicService.java
在最外层函数定义需要用到的变量和子类,String[]内容注意要和mainActivity中的对应

MyReceiver serviceReceiver;
AssetManager am;
String[] musics=new String[]{"beautiful.mp3","legendsneverdie.mp3","promise.mp3","wish.mp3"};
MediaPlayer mPlayer;
//当前状态,0x11表示没有播放,0x12代表正在播放,0x13代表暂停
int status=0x11;
//记录当前正在播放的音乐
int current=0;

onCreate函数
添加监听器、注册receiver,并向Activity发送广播

public void onCreate() {
    super.onCreate();
    am=getAssets();
    //创建BroadcastReceiver
    serviceReceiver=new MyReceiver();
    //创建IntentFilter(过滤器)
    IntentFilter filter=new IntentFilter();
    filter.addAction(MainActivity.CTL_ACTION);
    registerReceiver(serviceReceiver,filter);
    //创建MediaPlayer
    mPlayer=new MediaPlayer();
    //为MediaPlayer播放完成事件绑定监听器

    mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mp) {
            current++;
            if (current>=4)
            {
                current=0;
            }
            //发送广播通知Activity更改文本框
            Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
            sendIntent.putExtra("current",current);
            //发送广播,将被Activity组件中的BroadcastReceiver接收
            sendBroadcast(sendIntent);
            //准备播放音乐
            prepareAndPlay(musics[current]);
        }
    });
}

MyReceiver子类,接收MainActivity发来的信息,并发送广播,定义了接收到来自MainActivity的广播后的处理过程

public class MyReceiver extends BroadcastReceiver
{
    @Override
    public void onReceive(Context context, Intent intent) {
        int control =intent.getIntExtra("control",-1);
        switch (control)
        {
            //播放或暂停
            case 1:
                //原来处于没有播放状态
                if (status==0x11)
                {
                    //准备并播放音乐
                    prepareAndPlay(musics[current]);
                    status=0x12;
                }
                //原来处于播放状态
                else if (status==0x12)
                {
                    //暂停
                    mPlayer.pause();
                    //改变为暂停状态
                    status=0x13;
                }
                //原来处于暂停状态
                else if (status==0x13)
                {
                    //播放
                    mPlayer.start();
                    //改变状态
                    status=0x12;
                }
                break;
            //停止声音

            case 2:
                // 如果原来正在播放或暂停
                if (status == 0x12 || status == 0x13)
                {
                    // 停止播放
                    mPlayer.stop();
                    status = 0x11;
                }
                break;

            //播放上一首
            case 3:
                //原来处于没有播放或暂停状态
                if (status==0x11||status==0x13)
                {
                    if(current==0) {
                        current=3;
                        prepareAndPlay(musics[current]);
                    }
                    //准备并播放音乐
                    else {
                        current=current-1;
                        prepareAndPlay(musics[current]);
                    }
                    status=0x12;
                }
                //原来处于播放状态
                else if (status==0x12)
                {
                    //上一首//准备并播放音乐
                    if(current==0) {
                        current=3;
                        prepareAndPlay(musics[current]);
                    }
                    else {
                        current=current-1;
                        prepareAndPlay(musics[current]);
                    }
                }
                break;

            //播放下一首
            case 4:
                //原来处于没有播放或暂停状态
                if (status==0x11||status==0x13)
                {
                    if(current==3) {
                        current=0;
                        prepareAndPlay(musics[current]);
                    }   //准备并播放音乐
                    else {
                        current=current+1;
                        prepareAndPlay(musics[current]);
                    }
                    status=0x12;
                }
                //原来处于播放状态
                else if (status==0x12)
                {
                    //下一首
                    if(current==3) {
                        current=0;
                        prepareAndPlay(musics[current]);
                    }
                    else {
                        current=current+1;
                        prepareAndPlay(musics[current]);
                    }
                }
                break;
        }
        //广播通知Activity更改图标、文本框
        Intent sendIntent=new Intent(MainActivity.UPDATE_ACTION);
        sendIntent.putExtra("update",status);
        sendIntent.putExtra("current",current);
        //发送广播,将被Activity组件中的BroadcastReceiver接收
        sendBroadcast(sendIntent);
    }
}

prepareAndPlay函数,准备并播放音乐

private void prepareAndPlay(String music)
{
    try
    {
        //打开指定音乐文件
        AssetFileDescriptor afd=am.openFd(music);
        mPlayer.reset();
        //使用MediaPlayer加载指定的音乐文件
        mPlayer.setDataSource(afd.getFileDescriptor(),afd.getStartOffset(),afd.getLength());
        //准备声音
        mPlayer.prepare();
        //播放
        mPlayer.start();
    }catch (IOException e) {
        e.printStackTrace();
    }

到这里整个程序就基本完成了。

6.运行结果截图:

在这里插入图片描述

标签:11,status,05,current,Intent,2021,new,播放,mPlayer
来源: https://blog.csdn.net/qq_54590671/article/details/116673716