本文介绍 Android 开发中 Service 的使用方法及其实战案例，包括 APP 版本检测、下载及通知提醒等功能实现，并探讨 Service 生命周期及其重启策略。
Service 四大组件之二Activity
Service是一个没有操作界面的组件，类似于Window中的服务
本章任务 1使用Service进行APP版本检测
2使用Service进行APP版本下载
3使用Notfication进行消息提醒；
Service生命周期
onCreat 只会出现一次
onStartCoommand （非绑定直接进入） 开始执行命令
onDestroy （销毁）
onBind （绑定直接进入）
onUnbind （解除绑定）
Start 启动服务 onCreate（）onStartCoommand（）*** onDestroy
Bind绑定服务onCreate（）onBind（）**onUnbind（）onDestroy
Service开发步骤：
1.继承Service
2.注册Service
3.在android组件中启动Service
4.停止服务
通过startService()方法启动的Service，需要调用stopService()或者Service自己调用stopSelf()来终止。那么如果系统在显示调用stopService()或者stopSelf()之前终止了Service，应该如何重写启动Service呢。
我们注意到在上面的程序案例中，重写了Service里面onStartCommand方法，而该方法的返回值决定了当Service被系统终止后，系统该如何响应Service的重启。具体的方法签名如下：
public int onStartCommand(Intent intent, int flags, int startId)
该方法的返回值主要有：
Ø START_STICKY：描述了标准的重启行为。如果返回该值，那么当Service被系统杀死后重新启动时，将会调用onStartCommand方法。需要注意的是此时参数intent为null。
Ø START_NOT_STICKY：如果返回该值，当Service在执行完onStartCommand后被系统杀死，系统不会重启该服务。
Ø START_REDELIVER_INTENT：如果返回该值，当Service被系统杀死后重新启动时，情况与START_STICKY类似。不同的是Android将会保留杀死Service前最后一次传入onStartCommand的参数intent值，并作为参数传入到新创建的Service的onStartCommand方法中。
Ø START_STICKY_COMPATIBILITY：START_STICKY的兼容版本，但不保证Service被系统终止后一定能重启
package c.example.jreduch09;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.IBinder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
private Button start1;
private Button start2,startmp3;
private Button stop1,stop2;
private Button download1,download2;
private MyService myService;
//服务连接
private ServiceConnection serviceConnection=new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName,
IBinder iBinder) {
myService=((MyService.MyBinder) iBinder).getService();
}
@Override
public void onServiceDisconnected(ComponentName componentName) {
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
start1=(Button)findViewById(R.id.start1);
start2=(Button)findViewById(R.id.start2);
startmp3=(Button)findViewById(R.id.startmp3);
stop1=(Button)findViewById(R.id.stop1);
stop2=(Button)findViewById(R.id.stop2);
download1=(Button)findViewById(R.id.download1);
download2=(Button)findViewById(R.id.download2);
start1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent it=new Intent(MainActivity.this,MyService.class);
// it.putExtra("hh",4);
startService(it);
}
});
stop1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent it=new Intent(MainActivity.this,MyService.class);
stopService(it);
}
});
start2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent it=new Intent(MainActivity.this,MyService.class);
// bindService(it,serviceConnection,0);
bindService(it,serviceConnection,BIND_AUTO_CREATE);
}
});
stop2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//解除绑定
if (myService!=null){
unbindService(serviceConnection);}
}
});
startmp3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (myService!=null){
myService.playMusic();
}
}
});
//非绑定下载Service
download1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent it=new Intent(MainActivity.this,MyDownLoadService.class);
startService(it);
}
});
download2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent it=new Intent(MainActivity.this,MyDownLoadService.class);
stopService(it);
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
//解绑
if (myService!=null){
unbindService(serviceConnection);}
}
}
package c.example.jreduch09;
import android.app.Service;
import android.content.Intent;
import android.media.MediaPlayer;
import android.media.RingtoneManager;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
import java.io.IOException;
public class MyService extends Service {
private boolean pause=false;
public MyService() {
}
private MediaPlayer mediaPlayer;
public class MyBinder extends Binder {
public MyService getService(){
return MyService.this;
}
}
@Override
public void onCreate() {
super.onCreate();
mediaPlayer=new MediaPlayer();
// mediaPlayer=MediaPlayer.create(this,R.raw.i);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d("",intent.getExtras()+"");
playMusic();
return START_REDELIVER_INTENT;
// return super.onStartCommand(intent, flags, startId);
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
// throw new UnsupportedOperationException("Not yet implemented");
return new MyBinder();
}
@Override
public boolean onUnbind(Intent intent) {
return super.onUnbind(intent);
}
@Override
public void onDestroy() {
super.onDestroy();
if (mediaPlayer!=null){
mediaPlayer.stop();
}
// mediaPlayer.setDataSource();//路径
// mediaPlayer.setLooping();//循环
// mediaPlayer.prepare(); //准备
// mediaPlayer.start(); //开始
// mediaPlayer.pause(); mediaPlayer.stop();//暂停
//
// mediaPlayer.reset();
// mediaPlayer.setDataSource();
// mediaPlayer.setLooping();
// mediaPlayer.prepare();
// mediaPlayer.start();
//播放完成
// mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
// @Override
// public void onCompletion(MediaPlayer mediaPlayer) {
//
// }
// });
// mediaPlayer.seekTo();//进度条快进歌曲播放位置。
}
public void playMusic(){
if (mediaPlayer.isPlaying()){
mediaPlayer.pause();//暂停
pause=true;
}else {
if (pause){
mediaPlayer.start();
pause=false;
return;
}else {
try {
//设置播放路径
mediaPlayer.setDataSource(this, RingtoneManager
.getDefaultUri(RingtoneManager.TYPE_RINGTONE));
//单曲循环
mediaPlayer.setLooping(true);
mediaPlayer.prepare(); //准备
} catch (IOException e) {
e.printStackTrace();
}
//启动播放器
mediaPlayer.start();
}
}
}
}
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="c.example.jreduch09.MainActivity">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/start1"
android:text="启动服务（非绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/stop1"
android:text="停止服务（非绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/start2"
android:text="启动服务（绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/startmp3"
android:text="播放音乐（绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/stop2"
android:text="解除绑定（绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/download1"
android:text="开始下载（非绑定）"
/>
<Button
android:layout_width="match_parent"
android:layout_height="50dp"
android:id="@+id/download2"
android:text="停止下载（非绑定）"
/>
</LinearLayout>
</RelativeLayout>
版本检测与下载——Service
package c.example.jreduch09;
import android.app.DownloadManager;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.IBinder;
import android.widget.Toast;
import org.json.JSONException;
import org.json.JSONObject;
import c.example.jreduch09.util.HttpUtil;
import c.example.jreduch09.util.UrlUtil;
public class MyDownLoadService extends Service {
private int vid,i;
public MyDownLoadService() {
}
@Override
public void onCreate() {
super.onCreate();
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
// return super.onStartCommand(intent, flags, startId);
try {
vid = getPackageManager().getPackageInfo(this.getPackageName(), 0)
.versionCode;
String ur2 = UrlUtil.schoolUrl + "apk";
new Getapk().execute(ur2);
} catch (PackageManager.NameNotFoundException e) {
e.printStackTrace();
}
return START_REDELIVER_INTENT;
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@Override
public void onDestroy() {
super.onDestroy();
}
private void downLoad(){
DownloadManager downloadManager=(DownloadManager)
getSystemService(Context.DOWNLOAD_SERVICE);
String downUrl= UrlUtil.schoolUrl + "apk/cc.apk";
DownloadManager.Request request=new DownloadManager.Request(Uri.parse(downUrl));
request.setDestinationInExternalPublicDir("/"+getPackageName()+"/","zyf.apk");
request.setTitle("....下载");
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
downloadManager.enqueue(request);
}
public class Getapk extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... strings) {
// url= UrlUtil.schoolUrl+strings[0];
return HttpUtil.HttpGet(strings[0]);
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
if (s == null) {
Toast.makeText(getBaseContext(), "没有数据网路不好", Toast.LENGTH_SHORT).show();
} else {
try {
JSONObject obj = new JSONObject(s);
i= Integer.parseInt(obj.getString("vid"));
if (vid<i&&false){
Toast.makeText(getBaseContext(), "版本更新", Toast.LENGTH_SHORT).show();
downLoad();
}else{
Toast.makeText(getBaseContext(), "已经是版本更新", Toast.LENGTH_SHORT).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}
}
}
package c.example.jreduch09;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.view.WindowManager;
import android.widget.ImageView;
import com.gitonway.lee.niftymodaldialogeffects.lib.Effectstype;
import com.gitonway.lee.niftymodaldialogeffects.lib.effects.BaseEffects;
public class Main2Activity extends AppCompatActivity implements Main2Service.StopImg {
private ImageView show;
private boolean click=false;
private boolean run=true;
private int[] imgs={R.mipmap.a,R.mipmap.b,R.mipmap.c,R.mipmap.d,R.mipmap.e,R.mipmap.f,R.mipmap.h,R.mipmap.i,R.mipmap.j,R.mipmap.k,
R.mipmap.l,R.mipmap.m,R.mipmap.n,R.mipmap.o,R.mipmap.p,R.mipmap.q,R.mipmap.r,R.mipmap.s,R.mipmap.t};
private Effectstype[] types={Effectstype.Fadein,Effectstype.Fall,Effectstype.Fliph,Effectstype.Flipv,
Effectstype.Newspager,Effectstype.RotateBottom,Effectstype.RotateLeft,Effectstype.Shake,
Effectstype.Sidefill,Effectstype.SlideBottom,Effectstype.Slideright,Effectstype.Slidetop,Effectstype.Slideleft,
Effectstype.Slit};
private Handler handler=new Handler(){
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
start(msg.arg1,4000,msg.what);
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main2);
getSupportActionBar().hide();
show=(ImageView)findViewById(R.id.show);
show.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (click){
return;
}
click = true;
Intent intent = new Intent(Main2Activity.this,Main2Service.class);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startService(intent);
start(8,5000,8);
Main2Service.setMusicStop(Main2Activity.this);
new Thread(new ImgNext()).start();
}
});
}
public void stop() {
run = false;
}
public class ImgNext implements Runnable{
@Override
public void run() {
int i = -1;
int which = -1;
Message message;
while (i<imgs.length&&run){
if (which == types.length-1){
which = 0;
}
if (i == imgs.length-1){
i = 0;
}
try {
Thread.sleep(5000);
message = new Message();
i++;
which++;
message.what = i;
message.arg1 = which;
handler.sendMessage(message);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
if (!run){
message = new Message();
message.what = 10;
message.arg1 = 0;
handler.sendMessage(message);
}
}
}
private void start(int which,int mDuration,int img) {
Log.d("===whice>:",which+"");
show.setImageResource(imgs[img]);
BaseEffects animator = types[which].getAnimator();
if (mDuration != -1) {
animator.setDuration(Math.abs(mDuration));
}
animator.start(show);
}
}
package c.example.jreduch09;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.media.MediaPlayer;
import android.media.RingtoneManager;
import android.os.IBinder;
import java.io.IOException;
public class Main2Service extends Service {
private static StopImg stopImg;
private boolean pause=false;
private MediaPlayer mediaPlayer;
public Main2Service() {
}
@Override
public void onCreate() {
super.onCreate();
mediaPlayer=new MediaPlayer();
try {
mediaPlayer.setDataSource(this, RingtoneManager
.getDefaultUri(RingtoneManager.TYPE_RINGTONE));
mediaPlayer.prepare();
} catch (IOException e) {
e.printStackTrace();
}
// mediaPlayer=MediaPlayer.create(this,R.raw.i);
}
@Override
public IBinder onBind(Intent intent) {
// TODO: Return the communication channel to the service.
throw new UnsupportedOperationException("Not yet implemented");
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
mediaPlayer.start();
mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mediaPlayer) {
stopImg.stop();
}
});
return super.onStartCommand(intent, flags, startId);
}
@Override
public void onDestroy() {
super.onDestroy();
}
public static void setMusicStop(Context context){
stopImg = (StopImg) context;
}
public interface StopImg{
public void stop();
}
}
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="c.example.jreduch09.Main2Activity"> <ImageView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/show" /> </RelativeLayout>
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