Android Activity/Service/Broadcaster三大组件之间互相调用

Android Activity/Service/Broadcaster三大组件之间互相调用

发表于 2012 年 8 月 12 日 由 Ruthless

我们研究两个问题，
1、Service如何通过Broadcaster更改activity的一个TextView。
(研究这个问题，考虑到Service从服务器端获得消息之后，将msg返回给activity)

2、Activity如何通过Binder调用Service的一个方法。
(研究这个问题，考虑到与服务器端交互的动作，打包至Service，Activity只呈现界面，调用Service的方法)
 
结构图见如下：

 

效果图如下：

 

u
点击“start service”按钮，启动Service，然后更改Activity的UI。

点击“send msg to server”按钮调用Service的方法，显示NotificationBar

 

1、新建一个MyService类，继承Service

package com.ljq.activity;


import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.Binder;
import android.os.IBinder;

public class MyService extends Service {
 private NotificationManager notificationManager = null ;
 private final IBinder binder = new LocalBinder();

 @Override
 public void onCreate() {
  sendMsgtoActivty( "Service is oncreating.\n" );
 }

 @Override
 public IBinder onBind(Intent intent) {
  String msg = "Activity is sendding message to service,\n Service send msg to server!\n" ;
  sendMsgtoActivty(msg);
  return binder;
 }

 /**
  * 把信息传递给activity
  *
  * @param msg
  */
 private void sendMsgtoActivty(String msg) {
  Intent intent = new Intent( "com.android.Yao.msg" );
  intent.putExtra( "msg" , msg);
  this .sendBroadcast(intent);
 }

 @Override
 public void onDestroy() {
  super .onDestroy();
  if (notificationManager!= null ){
   notificationManager.cancel( 0 );
   notificationManager= null ;
  }
 }

 /**
  * 在状态栏显示通知
  *
  * @param msg
  */
 private void showNotification(String msg) {
  notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
  // 定义Notification的各种属性
  Notification notification = new Notification(R.drawable.icon,
          "A Message Coming!" , System.currentTimeMillis());
  //FLAG_AUTO_CANCEL   该通知能被状态栏的清除按钮给清除掉
  //FLAG_NO_CLEAR      该通知不能被状态栏的清除按钮给清除掉
  //FLAG_ONGOING_EVENT 通知放置在正在运行
  //FLAG_INSISTENT     是否一直进行，比如音乐一直播放，知道用户响应
  notification.flags |= Notification.FLAG_ONGOING_EVENT; // 将此通知放到通知栏的"Ongoing"即"正在运行"组中
  notification.flags |= Notification.FLAG_NO_CLEAR; // 表明在点击了通知栏中的"清除通知"后，此通知不清除，经常与FLAG_ONGOING_EVENT一起使用
  notification.flags |= Notification.FLAG_SHOW_LIGHTS;
  //DEFAULT_ALL     使用所有默认值，比如声音，震动，闪屏等等
  //DEFAULT_LIGHTS  使用默认闪光提示
  //DEFAULT_SOUNDS  使用默认提示声音
  //DEFAULT_VIBRATE 使用默认手机震动，需加上<uses-permission android:name="android.permission.VIBRATE" />权限
  notification.defaults = Notification.DEFAULT_LIGHTS;
  //叠加效果常量
  //notification.defaults=Notification.DEFAULT_LIGHTS|Notification.DEFAULT_SOUND;
  notification.ledARGB = Color.BLUE;
  notification.ledOnMS = 5000 ; //闪光时间，毫秒

  // 设置通知的事件消息
  //Intent notificationIntent =new Intent(MainActivity.this, MainActivity.class); // 点击该通知后要跳转的Activity
  Intent notificationIntent = new Intent(getApplicationContext(), MainActivity. class ); // 加载类，如果直接通过类名，会在点击时重新加载页面，无法恢复最后页面状态。
  notificationIntent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
  PendingIntent contentItent = PendingIntent.getActivity( this , 0 , notificationIntent, 0 );
  notification.setLatestEventInfo( this , "Message" , "Message:" + msg, contentItent);

  // 把Notification传递给NotificationManager
  notificationManager.notify( 0 , notification);

 }

 /**
  * 从activity获取信息
  *
  * @param msg
  */
 public void receiverMsgtoActivity(String msg){
  sendMsgtoActivty( "\n receiverMsgtoActivity:" +msg);
 }

 public void sendMsgtoServer(String msg) {
  showNotification(msg);
 }

 public class LocalBinder extends Binder {
  public MyService getService() {
   return MyService. this ;
  }
 }

}

2、新建MyBroadcastreceiver类，继承BroadcastReceiver，用来发送Intent启动服务

package com.ljq.activity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

/**
 * 发送Intent启动服务
 *
 * @author jiqinlin
 *
 */
public class MyBroadcastreceiver extends BroadcastReceiver {
 @Override
 public void onReceive(Context context, Intent intent) {
  Intent service = new Intent(context, MyService. class );
  context.startService(service);
 }

}

3、新建MainActivity类，其实是一个activity，用来呈现界面

package com.ljq.activity;

import java.util.List;

import android.app.Activity;
import android.app.ActivityManager;
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.util.Log;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity implements View.OnClickListener {
 private String msg = "" ;
 private TextView txtMsg;
 private UpdateReceiver receiver;
 private MyService myService;
 private final static String TAG=MainActivity. class .getSimpleName();

 @Override
 public void onCreate(Bundle savedInstanceState) {
  super .onCreate(savedInstanceState);
  setContentView(R.layout.main);

  txtMsg = (TextView) this .findViewById(R.id.txtMsg);
  this .findViewById(R.id.btnStart).setOnClickListener( this );
  this .findViewById(R.id.btnSend).setOnClickListener( this );

  //订阅广播Intent
  receiver = new UpdateReceiver();
  IntentFilter filter = new IntentFilter();
  filter.addAction( "com.android.Yao.msg" );
  this .registerReceiver(receiver, filter);

  //初始化时启动服务
  //Intent intent = new Intent(MainActivity.this, MyService.class);
  //this.bindService(intent, conn, BIND_AUTO_CREATE);
 }

 @Override
 protected void onDestroy() {
  super .onDestroy();
  //结束服务
  if (conn!= null ){
   unbindService(conn);
   myService= null ;
  }

 }

 public class UpdateReceiver extends BroadcastReceiver {

  @Override
  public void onReceive(Context context, Intent intent) {
   //获取service传过来的信息
   msg = intent.getStringExtra( "msg" );
   txtMsg.append(msg);
  }
 }

 private ServiceConnection conn = new ServiceConnection() {
  @Override
  public void onServiceConnected(ComponentName name, IBinder service) {
   myService = ((MyService.LocalBinder) service).getService();
   Log.i(TAG, "onServiceConnected myService: " +myService);
  }

  @Override
  public void onServiceDisconnected(ComponentName name) {
    myService = null ;
  }

 };

 @Override
 public void onClick(View v) {
  Intent intent = new Intent(MainActivity. this , MyService. class );
  switch (v.getId()) {
  case R.id.btnStart:
   //判断服务是否启动
   if ( false ==isServiceRunning( this , MyService. class .getName())){
    Log.i(TAG, "start " +MyService. class .getSimpleName()+ " service" );
    this .bindService(intent, conn, BIND_AUTO_CREATE);
   }
   Log.i(TAG, MyService. class .getName()+ " run status: " +isServiceRunning( this , MyService. class .getName()));
   break ;
  case R.id.btnSend:
   //判断服务是否启动
   if ( false ==isServiceRunning( this , MyService. class .getName())){
    Log.i(TAG, "start " +MyService. class .getSimpleName()+ " service" );
    this .bindService(intent, conn, BIND_AUTO_CREATE);
   }

   Log.i(TAG, MyService. class .getName()+ " run status: " +isServiceRunning( this , MyService. class .getName()));
   Log.i(TAG, "onClick myService: " +myService); //第一次启动服务时此处为null(小编认为虽然服务已启动成功，但是还没全部初始化)

   if (myService!= null ){
       myService.sendMsgtoServer( "i am sending msg to server" );
       //从activity传递信息给service
       myService.receiverMsgtoActivity( "this is a msg" );
      }
   break ;
  }
 }

 /**
  * 判断服务是否正在运行
  *
  * @param context
  * @param className 判断的服务名字：包名+类名
  * @return true在运行 false 不在运行
  */
 public static boolean isServiceRunning(Context context, String className) {
  boolean isRunning = false ;

  ActivityManager activityManager = (ActivityManager) context
    .getSystemService(Context.ACTIVITY_SERVICE);
  //获取所有的服务
  List<ActivityManager.RunningServiceInfo> services= activityManager.getRunningServices(Integer.MAX_VALUE);
  if (services!= null &&services.size()> 0 ){
   for (ActivityManager.RunningServiceInfo service : services){
    if (className.equals(service.service.getClassName())){
     isRunning= true ;
     break ;
    }
   }
  }

  return isRunning;
 }

}

4、main.xml布局文件

<? 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" >
 < TextView android:layout_width = "fill_parent"
  android:layout_height = "wrap_content"
  android:id = "@+id/txtMsg" />
 < LinearLayout
  xmlns:android = "http://schemas.android.com/apk/res/android"
  android:orientation = "horizontal"
  android:layout_width = "wrap_content"
  android:layout_height = "wrap_content" >
  < Button android:layout_width = "wrap_content"
   android:layout_height = "wrap_content"
   android:text = "start service"
   android:id = "@+id/btnStart" />
  < Button android:layout_width = "wrap_content"
   android:layout_height = "wrap_content"
   android:text = "send msg to server"
   android:id = "@+id/btnSend" />
 </ LinearLayout >
</ LinearLayout >

5、清单文件AndroidManifest.xml，用来配置组件等信息

<? xml version = "1.0" encoding = "utf-8" ?>
< manifest xmlns:android = "http://schemas.android.com/apk/res/android"
      package = "com.ljq.activity"
      android:versionCode = "1"
      android:versionName = "1.0" >
    < application android:icon = "@drawable/icon" android:label = "@string/app_name" >
        < activity android:name = ".MainActivity"
                  android:label = "@string/app_name" >
            < intent-filter >
                < action android:name = "android.intent.action.MAIN" />
                < category android:name = "android.intent.category.LAUNCHER" />
            </ intent-filter >
        </ activity >
        < service android:name = ".MyService" />
        < receiver android:name = ".MyBroadcastreceiver" />

    </ application >
    < uses-sdk android:minSdkVersion = "7" />

</ manifest >

 本案例代码下载地址

事实上，用Binder也可实现将值从Servcie传送至Activity。。。有兴趣的同志可以去看看这篇文章–>Android与Activity交互的本地服务示例