本文实例讲述了Android实现Activity、Service与Broadcaster三大组件之间互相调用的方法。分享给大家供大家参考，具体如下：

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：

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

代码：

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>

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