玩转Android---组件篇---Service(服务)

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Service是Andorid系统提供的四大组件之一，它的地位和Activity是并列的，只是使用的频率没有Activity高。Service就是运行于后台的一种服务程序，一般很少和用户交互，因此没有可视化界面。

定义一个Service类只要继承Service类即可，实现其生命周期中的方法就可以了，另外，一个定义好的Service组件必须要在AndoridManifest.xml文件中注册才能够使用。

Service有自己的生命周期，可以调用startService()启动一个Service或者使用bindService()来绑定一个service，还可以通过RPC(远程进程调用)机制来实现不同进程间Service的调用。

Service中定义了一系列和自身生命周期相关的方法：

onBind(Intent intent):是必须实现的一个方法，返回一个绑定的接口给Service。

onCreate()：当Service第一次被创建时，由系统调用。

onStart(Intent intent,int startId)：当通过startService()方法启动Service时，该方法被调用。

onDestroy()：当Service不再使用，系统调用该方法。

实例如下：

MyService.java

Java代码

/*
* @author hualang
*/
package org.hualang.service;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;
public class MyService extends Service {
@Override
public IBinder onBind(Intent intent) {
// TODO Auto-generated method stub
Log.i("SERVICE", "onBind.................");
Toast.makeText(MyService.this, "onBind.................", Toast.LENGTH_LONG).show();
return null;
}
public void onCreate()
{
Log.i("SERVICE", "onCreate................");
Toast.makeText(MyService.this, "onCreate................", Toast.LENGTH_LONG).show();
}
public void onStart(Intent intent,int startId)
{
Log.i("SERVICE", "onStart.................");
Toast.makeText(MyService.this, "onStart.................", Toast.LENGTH_LONG).show();
}
public void onDestroy()
{
Log.i("SERVICE", "onDestroy.................");
Toast.makeText(MyService.this, "onDestroy.................", Toast.LENGTH_LONG).show();
}
}

/* * @author hualang */package org.hualang.service;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.util.Log;import android.widget.Toast;public class MyService extends Service {@Overridepublic IBinder onBind(Intent intent) {// TODO Auto-generated method stubLog.i("SERVICE", "onBind.................");Toast.makeText(MyService.this, "onBind.................", Toast.LENGTH_LONG).show();return null;}public void onCreate(){Log.i("SERVICE", "onCreate................");Toast.makeText(MyService.this, "onCreate................", Toast.LENGTH_LONG).show();}public void onStart(Intent intent,int startId){Log.i("SERVICE", "onStart.................");Toast.makeText(MyService.this, "onStart.................", Toast.LENGTH_LONG).show();}public void onDestroy(){Log.i("SERVICE", "onDestroy.................");Toast.makeText(MyService.this, "onDestroy.................", Toast.LENGTH_LONG).show();}}

ServiceTest.java

Java代码

/*
* @author hualang
*/
package org.hualang.service;
import android.app.Activity;
import android.app.Service;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class ServiceTest extends Activity {
/** Called when the activity is first created. */
private Button startService,stopService,bindService,unbindService;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
startService=(Button)findViewById(R.id.startButton);
stopService=(Button)findViewById(R.id.stopButton);
bindService=(Button)findViewById(R.id.bindButton);
unbindService=(Button)findViewById(R.id.unbindButton);
startService.setOnClickListener(startListener);
stopService.setOnClickListener(stopListener);
bindService.setOnClickListener(bindListener);
unbindService.setOnClickListener(unbindListener);
}
private OnClickListener startListener=new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setAction("org.hualang.service.action.MYSERVICE");
startService(intent);
}
};
private OnClickListener stopListener=new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setAction("org.hualang.service.action.MYSERVICE");
stopService(intent);
}
};
private ServiceConnection conn=new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
// TODO Auto-generated method stub
Log.i("SERVICE", "connection success");
Toast.makeText(ServiceTest.this, "connection success", Toast.LENGTH_LONG).show();
}
@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
Log.i("SERVICE", "connection success");
Toast.makeText(ServiceTest.this, "connection failure", Toast.LENGTH_LONG).show();
}
};
private OnClickListener bindListener=new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setAction("org.hualang.service.action.MYSERVICE");
bindService(intent,conn,Service.BIND_AUTO_CREATE);
}
};
private OnClickListener unbindListener=new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Intent intent=new Intent();
intent.setAction("org.hualang.service.action.MYSERVICE");
unbindService(conn);
}
};
}

/* * @author hualang */package org.hualang.service;import android.app.Activity;import android.app.Service;import android.content.ComponentName;import android.content.Intent;import android.content.ServiceConnection;import android.os.Bundle;import android.os.IBinder;import android.util.Log;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class ServiceTest extends Activity {    /** Called when the activity is first created. */private Button startService,stopService,bindService,unbindService;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        startService=(Button)findViewById(R.id.startButton);        stopService=(Button)findViewById(R.id.stopButton);        bindService=(Button)findViewById(R.id.bindButton);        unbindService=(Button)findViewById(R.id.unbindButton);        startService.setOnClickListener(startListener);        stopService.setOnClickListener(stopListener);        bindService.setOnClickListener(bindListener);        unbindService.setOnClickListener(unbindListener);            }    private OnClickListener startListener=new OnClickListener()    {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent=new Intent();intent.setAction("org.hualang.service.action.MYSERVICE");startService(intent);}        };    private OnClickListener stopListener=new OnClickListener()    {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent=new Intent();intent.setAction("org.hualang.service.action.MYSERVICE");stopService(intent);}        };    private ServiceConnection conn=new ServiceConnection()    {@Overridepublic void onServiceConnected(ComponentName name, IBinder service) {// TODO Auto-generated method stubLog.i("SERVICE", "connection success");Toast.makeText(ServiceTest.this, "connection success", Toast.LENGTH_LONG).show();}@Overridepublic void onServiceDisconnected(ComponentName name) {// TODO Auto-generated method stubLog.i("SERVICE", "connection success");Toast.makeText(ServiceTest.this, "connection failure", Toast.LENGTH_LONG).show();}        };    private OnClickListener bindListener=new OnClickListener()    {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent=new Intent();intent.setAction("org.hualang.service.action.MYSERVICE");bindService(intent,conn,Service.BIND_AUTO_CREATE);}        };    private OnClickListener unbindListener=new OnClickListener()    {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubIntent intent=new Intent();intent.setAction("org.hualang.service.action.MYSERVICE");unbindService(conn);}        };}

在AndroidManifest.xml文件中注册Service如下

Java代码

<service android:name="MyService">
<intent-filter>
<action android:name="org.hualang.service.action.MYSERVICE"/>
</intent-filter>
</service>

<service android:name="MyService"><intent-filter><action android:name="org.hualang.service.action.MYSERVICE"/></intent-filter></service>

main.xml布局文件

Java代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button
android:text="启动Service"
android:id="@+id/startButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:text="停止Service"
android:id="@+id/stopButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:text="绑定Service"
android:id="@+id/bindButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:text="解除绑定unbindService"
android:id="@+id/unbindButton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:orientation="vertical"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    ><Buttonandroid:text="启动Service"android:id="@+id/startButton"android:layout_width="fill_parent"android:layout_height="wrap_content"/><Buttonandroid:text="停止Service"android:id="@+id/stopButton"android:layout_width="fill_parent"android:layout_height="wrap_content"/><Buttonandroid:text="绑定Service"android:id="@+id/bindButton"android:layout_width="fill_parent"android:layout_height="wrap_content"/><Buttonandroid:text="解除绑定unbindService"android:id="@+id/unbindButton"android:layout_width="fill_parent"android:layout_height="wrap_content"/></LinearLayout>

不解释，看运行结果就会明白

（1）当点击“启动Servcie”会先弹出"onCreate"，然后弹出"onStart"的Toast，在LogCat中会看到先显示

的也是

onCreate

onStart