Android学习总结——Service组件

从Service的启动方式上，可以将Service分为Started Service和Bound Service。在使用Service时，要想系统能够找到此自定义Service，无论哪种类型，都需要在AndroidManifest.xml中声明：

<service android:name=".MyService">

一：StartService方式启动服务

Started Service相对比较简单，通过context.startService(Intent serviceIntent)启动Service，context.stopService(Intent serviceIntent)停止此Service。

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.servicetest">

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<service android:name=".MyService">
</service>
</application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:orientation="vertical"
tools:context="com.example.servicetest.MainActivity">

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="启动服务"
android:id="@+id/btn_StartService" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="停止服务"
android:id="@+id/btn_StopService" />
</LinearLayout>

MainActivity：

package com.example.servicetest;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
private Button startService;
private Button stopService;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startService=(Button)findViewById(R.id.btn_StartService);
stopService=(Button) findViewById(R.id.btn_StopService);

startService.setOnClickListener(this);
stopService.setOnClickListener(this);
}

@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.btn_StartService:
//启动服务
Intent intentStart=new Intent(MainActivity.this,MyService.class);
startService(intentStart);
break;
case R.id.btn_StopService:
//停止服务
Intent intentStop=new Intent(MainActivity.this,MyService.class);
stopService(intentStop);
break;
}
}
}

MyService：

package com.example.servicetest;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
* Created by xch on 2016/9/5.
*/
public class MyService extends Service{

private boolean flag=true;

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

@Override
public void onCreate() {
super.onCreate();
Log.i("tag","服务被创建！");

}

@Override
public void onDestroy() {
super.onDestroy();
Log.i("tag","服务被销毁！");
new MyThread().setFlagFalse();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {

new MyThread().start();

return super.onStartCommand(intent, flags, startId);
}

class MyThread extends Thread{
public void setFlagFalse(){
flag=false;
}
@Override
public void run() {
super.run();

while (flag){
//每隔一秒钟打印当前时间一次
//设置时间打印格式
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//24小时制
Date date=new Date();
String time=sdf.format(date);
Log.i("date",time);
try {
//沉睡1秒
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
}

二. BoundService方式启动服务

bindService启动流程: context.bindService() ——> onCreate() ——> onBind() ——> Service running ——> onUnbind() ——> onDestroy() ——> Service stop

MainActivity:

package com.example.servicetest2;

import android.content.ComponentName;
import android.content.Context;
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 implements View.OnClickListener{
private Button bindService,unBindService;
private Intent intent;
private MyServiceConn conn=new MyServiceConn();

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

bindService=(Button)findViewById(R.id.btn_BindService);
unBindService=(Button)findViewById(R.id.btn_UnBindService);

bindService.setOnClickListener(this);
unBindService.setOnClickListener(this);
}

@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btn_BindService:
intent=new Intent(MainActivity.this,MyService.class);
bindService(intent,conn, Context.BIND_AUTO_CREATE);
break;
case R.id.btn_UnBindService:
intent=new Intent(MainActivity.this,MyService.class);
unbindService(conn);
break;
}
}
private class MyServiceConn implements ServiceConnection {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
//在服务绑定成功的时候执行
}

@Override
public void onServiceDisconnected(ComponentName name) {
//当服务所在的进程被杀死，或崩溃的时候执行
}
}
}

MyService:

package com.example.servicetest2;

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
* Created by xch on 2016/9/7.
*/
public class MyService extends Service {
private boolean flag=true;
private MyThread thread=new MyThread();

@Nullable
@Override
public IBinder onBind(Intent intent) {
thread.start();
return null;
}

@Override
public void onCreate() {
Log.i("service","服务被创建！");
super.onCreate();
}

@Override
public void onDestroy() {
super.onDestroy();
Log.i("service","服务被销毁！");
thread.setFlagFalse();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
return super.onStartCommand(intent, flags, startId);
}

class MyThread extends Thread{
public void setFlagFalse(){
flag=false;
}

@Override
public void run() {
super.run();
while (flag){
Date date=new Date();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-mm-dd HH:mm:ss");
Log.i("date",sdf.format(date));
try {
sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}
}
}

三.Service与Activity之间通讯

BoundService可以实现，但是startService没有这个特点。这里需要注意的是，利用bindService启动的Service无法获取这个Service对象，所以这里需要在Service中将对象返回，既然有返回就需要接收。so，看代码：

MyService：

package com.example.servicetest2;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.util.Log;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
* Created by xch on 2016/9/7.
*/
public class MyService extends Service {
private boolean flag=true;
private MyThread thread;
private String format="yyyy-mm-dd HH:mm:ss";

//更改系统时间的输出格式
public void setFormat(String format){
this.format=format;
}

public void changeFormat(String format){
if(thread!=null){
//调用方法，更改时间输出格式
setFormat(format);
}
}

@Nullable
@Override
public IBinder onBind(Intent intent) {
thread.start();
//将代理类返回回去
return new ServiceBinder();
}

@Override
public void onCreate() {
Log.i("service","服务被创建！");
thread=new MyThread();
super.onCreate();
}

@Override
public void onDestroy() {
super.onDestroy();
Log.i("service","服务被销毁！");
thread.setFlagFalse();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
return super.onStartCommand(intent, flags, startId);
}

class MyThread extends Thread{
public void setFlagFalse(){
flag=false;
}

@Override
public void run() {
super.run();
while (flag){
Date date=new Date();
SimpleDateFormat sdf=new SimpleDateFormat(format);
Log.i("date",sdf.format(date));
try {
sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}

}
}

/**
* 当前服务的代理类，即可使用changeFormat()方法
* 需要通过IBinder将这个代理类返回回去,即onBinder()方法
*/
public class ServiceBinder extends Binder{
public void changeServiceBinder(String format){
if(thread!=null){
changeFormat(format);
}
}

}
}

这里需要在service中定义一个代理类，并利用onBinder()方法返回去。
MainActivity：

package com.example.servicetest2;

import android.content.ComponentName;
import android.content.Context;
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 implements View.OnClickListener{
private Button bindService,unBindService,changeFormat;
private Intent intent;
private MyServiceConn conn=new MyServiceConn();
//接收到的service对象
private MyService.ServiceBinder serviceBinder;

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

bindService=(Button)findViewById(R.id.btn_BindService);
unBindService=(Button)findViewById(R.id.btn_UnBindService);
changeFormat=(Button)findViewById(R.id.btn_changeFormat);

bindService.setOnClickListener(this);
unBindService.setOnClickListener(this);
changeFormat.setOnClickListener(this);
}

@Override
public void onClick(View v) {
switch (v.getId()){
case R.id.btn_BindService:
intent=new Intent(MainActivity.this,MyService.class);
bindService(intent,conn, Context.BIND_AUTO_CREATE);
break;
case R.id.btn_UnBindService:
intent=new Intent(MainActivity.this,MyService.class);
unbindService(conn);
break;
case R.id.btn_changeFormat:
serviceBinder.changeServiceBinder("HH:mm:ss");
break;
}
}
private class MyServiceConn implements ServiceConnection {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
//在服务绑定成功的时候执行，同时接收到了IBinder对象（类型为代理类对象，因为onBinder方法返回了代理类对象）
serviceBinder= (MyService.ServiceBinder) service;
}

@Override
public void onServiceDisconnected(ComponentName name) {
//当服务所在的进程被杀死，或崩溃的时候执行
}
}
}

这里实现了ServiceConnection接口的自定义类需要实现如上两个方法，其中onServiceConnected(ComponentName name, IBinder service)方法能获取onBinder()返回的service对象。

结果：