系出名门Android(4) - 活动(Activity), 服务(Service), 广播(Broadcast), 广播接收器(BroadcastReceiv...

系出名门Android(4) - 活动(Activity), 服务(Service), 广播(Broadcast), 广播接收器(BroadcastReceiver)


作者：webabcd


介绍
在 Android 中使用 Activity, Service, Broadcast, BroadcastReceiver
活动(Activity) - 用于表现功能
服务(Service) - 相当于后台运行的 Activity
广播(Broadcast) - 用于发送广播
广播接收器(BroadcastReceiver) - 用于接收广播
Intent - 用于连接以上各个组件，并在其间传递消息


1、演示 Activity 的基本用法，一个 Activity 启动另一个 Activity，启动另一个 Activity 时为其传递参数，被启动的 Activity 返回参数给启动者的 Activity
Main.java

代码

package com.webabcd.activity;


import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;


public class Main extends Activity {


 TextView txt;


 /** Called when the activity is first created. */

 @Override

 public void onCreate(Bundle savedInstanceState) {

 super.onCreate(savedInstanceState);

 this.setContentView(R.layout.main);


 txt = (TextView) this.findViewById(R.id.txt);

 txt.setText("Activity 1");


 Button btn = (Button) this.findViewById(R.id.btn);

 btn.setText("启动另一个Activity");

 btn.setOnClickListener(new Button.OnClickListener() {

 @Override

 public void onClick(View v) {


 // 实例化 Intent，指定需要启动的 Activity

 Intent intent = new Intent();

 intent.setClass(Main.this, MyActivity.class);


 // 实例化 Bundle，设置需要传递的参数

 Bundle bundle = new Bundle();

 bundle.putString("name", "webabcd");

 bundle.putDouble("salary", 100.13);


 // 将需要传递的参数赋值给 Intent 对象

 intent.putExtras(bundle);


 // startActivity(intent); // 启动指定的 Intent（不等待返回结果）

 // Main.this.finish();


 // 启动指定的 Intent，并等待返回结果

 // 其中第二个参数如果大于等于零，则返回结果时会回调 onActivityResult() 方法

 startActivityForResult(intent, 0);

 }

 });


 Log.d("MyDebug", "onCreate");

 }


 // 被启动的 Activity 返回结果时的回调函数

 @Override

 protected void onActivityResult(int requestCode, int resultCode, Intent data) {

 if (resultCode == Activity.RESULT_OK){

 Bundle bundle = data.getExtras();


 String name = bundle.getString("name");

 double salary = bundle.getDouble("salary");


 txt.setText("Activity 1" + "\n名字：" + name + "\n薪水：" + String.valueOf(salary));

 }

 }


 @Override

 protected void onStart() {

 // TODO Auto-generated method stub

 super.onStart();


 Log.d("MyDebug", "onStart");

 }


 @Override

 protected void onStop() {

 // TODO Auto-generated method stub

 super.onStop();


 Log.d("MyDebug", "onStop");

 }


 @Override

 protected void onRestart() {

 // TODO Auto-generated method stub

 super.onRestart();


 Log.d("MyDebug", "onRestart");

 }


 @Override

 protected void onPause() {

 // TODO Auto-generated method stub

 super.onPause();


 Log.d("MyDebug", "onPause");

 }


 @Override

 protected void onResume() {

 // TODO Auto-generated method stub

 super.onResume();


 Log.d("MyDebug", "onResume");

 }


 @Override

 protected void onDestroy() {

 // TODO Auto-generated method stub

 super.onDestroy();


 Log.d("MyDebug", "onDestroy");

 }

}


MyActivity.java


代码 

package com.webabcd.activity;


import android.app.Activity;

import android.content.Intent;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;


// 被另一个 Activity 所启动的 Activity

public class MyActivity extends Activity {


 Intent intent;


 /** Called when the activity is first created. */

 @Override

 public void onCreate(Bundle savedInstanceState) {

 super.onCreate(savedInstanceState);

 this.setContentView(R.layout.main2);


 // 获取启动者传递过来的参数

 intent = this.getIntent();

 Bundle bundle = intent.getExtras(); 

 String name = bundle.getString("name");

 double salary = bundle.getDouble("salary");


 TextView txt = (TextView) this.findViewById(R.id.txt);

 txt.setText("Activity 2" + "\n名字：" + name + "\n薪水：" + String.valueOf(salary));


 Button btn = (Button) this.findViewById(R.id.btn);

 btn.setText("返回前一个Activity");

 btn.setOnClickListener(new Button.OnClickListener() {

 public void onClick(View v) {

 // 返回参数给启动者

 MyActivity.this.setResult(Activity.RESULT_OK, intent);

 MyActivity.this.finish();

 }

 });

 }

}



AndroidManifest.xml


代码 

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

 package="com.webabcd.activity" android:versionCode="1"

 android:versionName="1.0">

 <application android:icon="@drawable/icon" android:label="@string/app_name">

 <activity android:name=".Main" android:label="@string/app_name">

 <intent-filter>

 <action android:name="android.intent.action.MAIN" />

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

 </intent-filter>

 </activity>

 <!--

 如果有需要用到的 Activity ，则都要在这里做相应的配置

 -->

 <activity android:name=".MyActivity" android:label="Activity 2" />

 </application>

 <uses-sdk android:minSdkVersion="3" />

</manifest> 



2、Service, Broadcast, BroadcastReceiver 的演示

Main.java


代码 

package com.webabcd.service;


import android.app.Activity;

import android.content.BroadcastReceiver;

import android.content.ComponentName;

import android.content.Context;

import android.content.Intent;

import android.content.IntentFilter;

import android.content.ServiceConnection;

import android.os.Bundle;

import android.os.IBinder;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.TextView;


/*

 * startService() 和 bindService() 的区别 

 * startService() - 正常理解就好

 * bindService() - 使当前上下文对象（本例中就是 Activity）通过一个 ServiceConnection 对象邦定到指定的 Service 。这样，如果上下文对象销毁了的话，那么其对应的 Service 也会被销毁

 */

public class Main extends Activity implements OnClickListener {


 private TextView txtMsg;


 @Override

 public void onCreate(Bundle savedInstanceState) {

 super.onCreate(savedInstanceState);

 setContentView(R.layout.main);


 setTitle("android 之 service");


 this.findViewById(R.id.btnStart).setOnClickListener(this);

 this.findViewById(R.id.btnStop).setOnClickListener(this);

 this.findViewById(R.id.btnBind).setOnClickListener(this);

 this.findViewById(R.id.btnUnbind).setOnClickListener(this);


 txtMsg = (TextView)this.findViewById(R.id.txtMsg);


 // 实例化自定义的 BroadcastReceiver

 receiver = new UpdateReceiver();

 IntentFilter filter = new IntentFilter();

 // 为 BroadcastReceiver 指定 action ，使之用于接收同 action 的广播

 filter.addAction("com.webabcd.service.msg");


 // 以编程方式注册 BroadcastReceiver 。配置方式注册 BroadcastReceiver 的例子见 AndroidManifest.xml 文件

 // 一般在 OnStart 时注册，在 OnStop 时取消注册

 this.registerReceiver(receiver, filter);

 // this.unregisterReceiver(receiver);


 }


 @Override

 public void onClick(View v) {

 Intent intent = new Intent(Main.this, MyService.class);

 switch (v.getId()) {

 case R.id.btnStart:

 this.startService(intent);

 break;

 case R.id.btnStop:

 this.stopService(intent);

 break;

 case R.id.btnBind:

 this.bindService(intent, conn, Context.BIND_AUTO_CREATE);

 break;

 case R.id.btnUnbind:

 this.unbindService(conn);

 break;

 }

 }


 // bindService() 所需的 ServiceConnection 对象

 private ServiceConnection conn = new ServiceConnection() {

 @Override

 public void onServiceConnected(ComponentName className, IBinder service) {


 }

 @Override

 public void onServiceDisconnected(ComponentName className) {


 }

 };


 private String msg="";

 private UpdateReceiver receiver;

 // 实现一个 BroadcastReceiver，用于接收指定的 Broadcast

 public class UpdateReceiver extends BroadcastReceiver{


 @Override

 public void onReceive(Context context, Intent intent) {

 msg = intent.getStringExtra("msg");


 txtMsg.append(msg + "\n");

 }


 }

}


MyService.java


代码 

package com.webabcd.service;


import android.app.Service;

import android.content.Intent;

import android.os.IBinder;

import android.util.Log;


// 演示 Service 的生命周期。具体信息运行程序后在 LogCat 中查看

public class MyService extends Service {


 @Override

 public IBinder onBind(Intent intent) {


 Log.d("MyDebug", "onBind");

 sendMsg("onBind");


 // TODO Auto-generated method stub

 return null;

 }


 @Override

 public void onCreate() {

 // TODO Auto-generated method stub

 super.onCreate();


 Log.d("MyDebug", "onCreate");

 sendMsg("onCreate");

 }


 @Override

 public void onDestroy() {

 // TODO Auto-generated method stub

 super.onDestroy();


 Log.d("MyDebug", "onDestroy");

 sendMsg("onDestroy");

 }


 @Override

 public void onRebind(Intent intent) {

 // TODO Auto-generated method stub

 super.onRebind(intent);


 Log.d("MyDebug", "onRebind");

 sendMsg("onRebind");

 }


 @Override

 public void onStart(Intent intent, int startId) {

 super.onStart(intent, startId);


 Log.d("MyDebug", "onStart");

 sendMsg("onStart");

 }


 @Override

 public boolean onUnbind(Intent intent) {


 Log.d("MyDebug", "onUnbind");

 sendMsg("onUnbind");


 // TODO Auto-generated method stub

 return super.onUnbind(intent);

 }


 // 发送广播信息

 private void sendMsg(String msg){

 // 指定广播目标的 action （注：指定了此 action 的 receiver 会接收此广播）

 Intent intent = new Intent("com.webabcd.service.msg");

 // 需要传递的参数

 intent.putExtra("msg", msg);

 // 发送广播

 this.sendBroadcast(intent);

 }

}



MyBootReceiver.java


代码 

package com.webabcd.service;


import android.content.BroadcastReceiver;

import android.content.Context;

import android.content.Intent;

import android.util.Log;


public class MyBootReceiver extends BroadcastReceiver {


 // 用于接收满足条件的 Broadcast（相应的 Broadcast 的注册信息详见 AndroidManifest.xml ，当系统启动完毕后会调用这个广播接收器）

 @Override

 public void onReceive(Context arg0, Intent arg1) {

 Log.d("MyDebug", "onReceive");


 // 启动服务

 Intent service = new Intent(arg0, MyService.class);

 arg0.startService(service);

 }


}



AndroidManifest.xml


代码 

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

 package="com.webabcd.service" android:versionCode="1"

 android:versionName="1.0">

 <application android:icon="@drawable/icon" android:label="@string/app_name">

 <activity android:name=".Main" android:label="@string/app_name">

 <intent-filter>

 <action android:name="android.intent.action.MAIN" />

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

 </intent-filter>

 </activity>


 <!--

 如果有需要用到的 service ，则都要在这里做相应的配置

 -->

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


 <!--

 注册一个 BroadcastReceiver

 其 intent-filter 为 android.intent.action.BOOT_COMPLETED（用于接收系统启动完毕的 Broadcast）

 -->

 <receiver android:name=".MyBootReceiver">

 <intent-filter>

 <action android:name="android.intent.action.BOOT_COMPLETED" />

 </intent-filter>

 </receiver>

 </application>


 <!--

 接受系统启动完毕的 Broadcast 的权限

 -->

 <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

 <uses-sdk android:minSdkVersion="3" />

</manifest>