Android——用Activity和Service实现简单的音乐播放器

一、只用Activity 容易出现问题

xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="/apk/res/android"xmlns:tools="/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"tools:context="com.example.chenshuai.myapplication.ActivityMusic"android:orientation="vertical"><TextViewandroid:layout_width="match_parent"android:layout_height="40sp"android:text="播放状态"android:textSize="20sp"android:gravity="center_horizontal"android:id="@+id/tv_1"/><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"><Buttonandroid:layout_width="0dp"android:layout_height="wrap_content"android:layout_weight="1"android:text="播放"android:onClick="play_onclick"/><Buttonandroid:layout_width="0dp"android:layout_height="wrap_content"android:layout_weight="1"android:text="暂停"android:onClick="pause_onclick"/><Buttonandroid:layout_width="0dp"android:layout_height="wrap_content"android:layout_weight="1"android:text="停止"android:onClick="stop_onclick"/><Buttonandroid:layout_width="0dp"android:layout_height="wrap_content"android:layout_weight="1"android:text="退出"android:onClick="exit_onclick"/></LinearLayout></LinearLayout>

java

package com.example.chenshuai.myapplication;import android.media.MediaPlayer;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.TextView;public class ActivityMusic extends AppCompatActivity {TextView tv_1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_activity_music);tv_1 = (TextView)findViewById(R.id.tv_1);tv_1.setText("播放状态：停止播放。。。");}//媒体播放器 定义成员变量private MediaPlayer mediaPlayer;public void play_onclick(View view){if (mediaPlayer == null) {//调用MediaPlayer的静态方法createmediaPlayer = MediaPlayer.create(this, R.raw.tangren);}mediaPlayer.start();tv_1.setText("播放状态：正在播放。。。");}public void stop_onclick(View view){if (mediaPlayer != null) {mediaPlayer.stop();//停止mediaPlayer.reset();//重置mediaPlayer.release();//释放资源mediaPlayer = null;//重新赋值为空 }tv_1.setText("播放状态：停止播放。。。");}public void pause_onclick(View view){if (mediaPlayer != null && mediaPlayer.isPlaying()){mediaPlayer.pause();tv_1.setText("播放状态：暂停播放。。。");}}public void exit_onclick(View view){stop_onclick(view);finish();}}

效果：

二、用Service实现

同一个xml

ActivityMusicservice.java

package com.example.chenshuai.myapplication;import android.content.Intent;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.TextView;public class ActivityMusicservice extends AppCompatActivity {TextView tv_1;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_activity_music);tv_1 = (TextView)findViewById(R.id.tv_1);tv_1.setText("播放状态11：停止播放。。。");}public void play_onclick(View view){Intent intent = new Intent(this,MyServiceMusic.class);intent.putExtra("action","play");startService(intent);tv_1.setText("播放状态11：正在播放。。。");}public void stop_onclick(View view){Intent intent = new Intent(this,MyServiceMusic.class);intent.putExtra("action","stop");startService(intent);tv_1.setText("播放状态11：停止播放。。。");}public void pause_onclick(View view){Intent intent = new Intent(this,MyServiceMusic.class);intent.putExtra("action","pause");startService(intent);tv_1.setText("播放状态11：暂停播放。。。");}public void exit_onclick(View view){stop_onclick(view);finish();}}

MyServiceMusic.java

package com.example.chenshuai.myapplication;import android.app.Service;import android.content.Intent;import android.media.MediaPlayer;import android.os.IBinder;public class MyServiceMusic extends Service {public MyServiceMusic() {}@Overridepublic IBinder onBind(Intent intent) {// TODO: Return the communication channel to the service.throw new UnsupportedOperationException("Not yet implemented");}private MediaPlayer mediaPlayer;@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {//获取意图传递的信息String action = intent.getStringExtra("action");switch (action){case "play":if (mediaPlayer == null){mediaPlayer = MediaPlayer.create(this,R.raw.onceagain);}mediaPlayer.start();break;case "stop":if (mediaPlayer !=null){mediaPlayer.stop();mediaPlayer.reset();mediaPlayer.release();mediaPlayer = null;}break;case "pause":if (mediaPlayer !=null && mediaPlayer.isPlaying()){mediaPlayer.pause();}break;}return super.onStartCommand(intent, flags, startId);}}

minifest.xml

<serviceandroid:name=".MyServiceMusic"android:enabled="true"android:exported="true" />

效果：