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

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

器(BroadcastReceiver)【收藏】

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>

OK