组件通信实例解析

通过一个例子熟悉安卓组件通信：

第一：编写MainActivity：

package com.momo.componentcommunication;import android.app.Activity;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class MainActivity extends Activity {public static final int CMD_STOP_SERVICE = 0;// 定义一个常量作为停止服务的标记private Button btnStart;// 启动服务按钮private Button btnStop;// 关闭服务按钮private TextView txtShow; // 用来接收Service传递过来的数据private DataReciver dataReciver;// 用来接收来自于Service的数据private OnClickListener myOnClickListener = new OnClickListener() {@Overridepublic void onClick(View v) {// TODO Auto-generated method stubswitch (v.getId()) {case R.id.btnStart:/** 创建Intent对象 */Intent startService = new Intent(MainActivity.this,RandomService.class);MainActivity.this.startService(startService);// 发送Intent启动Servicebreak;case R.id.btnStop:/** 创建Intent对象 */Intent stopService = new Intent();stopService.setAction("com.momo.componentcommunication.RandomService.STOPACTION");stopService.putExtra("cmd", CMD_STOP_SERVICE);sendBroadcast(stopService);// 发送广播break;default:break;}}};/** * @author Administrator * @description 主要实现 Activity、Service、Broadcast Receiver 之间的通信 具体描述：在 *              Activity中通过单击启动Service按钮来启动一个Service,而Service就会启动一个线程， *              让该线程定时产生一个随机数，并将其封装到Intent对象中传递给Activity，Activity接收到Intent后 *              提取其中的信息将其显示到TextView控件上面；在服务运行的时候，可以单击Activity上的停止按钮来停止服 务。 */@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);init();// 初始化}/** * 初始化界面组件 */private void init() {/** 获取资源文件中的界面组件 */btnStart = (Button) findViewById(R.id.btnStart);btnStop = (Button) findViewById(R.id.btnStop);txtShow = (TextView) findViewById(R.id.txtShow);btnStart.setOnClickListener(myOnClickListener);btnStop.setOnClickListener(myOnClickListener);}/** * 单击按钮的监听器 */@Overrideprotected void onStart() {// TODO Auto-generated method stubdataReciver = new DataReciver();IntentFilter filter = new IntentFilter();// 创建IntentFilter对象filter.addAction("main_activity");registerReceiver(dataReciver, filter);// 注册Broadcast Receiversuper.onStart();}@Overrideprotected void onStop() {// TODO Auto-generated method stubunregisterReceiver(dataReciver);// 取消注册Broadcast Receiversuper.onStop();}/** *  * @author Administrator *         内部类描述：服务启动后也会向Activity发Intent，所以Activity也必须注册一个Broadcast *         Receiver组件 用来接受Intent，注册之前需要编写实现了Broadcast Receiver 的子类，如下 * */private class DataReciver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// TODO Auto-generated method stubdouble data = intent.getDoubleExtra("data", 0);txtShow.setText("来自于Service的数据：" + data);// 将接收到的数据显示在屏幕上}}}

第二：编写RandomService：

package com.momo.componentcommunication;import android.app.Service;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.content.IntentFilter;import android.os.IBinder;import android.util.Log;public class RandomService extends Service {public static final String TAG = "MYSERVICE";private boolean flag;// 线程是否执行的标志CommandReceiver cmdReceiver;/** * 重写onCreate方法 */@Overridepublic void onCreate() {// TODO Auto-generated method stubLog.i(TAG, "MyService:onCreate()");flag = true;// 设置线程执行状态为：执行状态cmdReceiver = new CommandReceiver();super.onCreate();}@Overridepublic IBinder onBind(Intent intent) {// TODO Auto-generated method stubLog.i(TAG, "MyService:onBind()");return null;}@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {// TODO Auto-generated method stubLog.i(TAG, "MyService:onStartCommand");IntentFilter filter = new IntentFilter();// 创建IntentFilter对象registerReceiver(cmdReceiver, filter);// 注册Broadcast ReceiverdoJob();// 调用方法启动线程return super.onStartCommand(intent, flags, startId);}@Overridepublic void onDestroy() {// TODO Auto-generated method stubLog.i(TAG, "MyService:onDestroy");unregisterReceiver(cmdReceiver);// 取消注册Broadcast Receiversuper.onDestroy();}public void doJob() {new Thread() {// 创建一个新线程public void run() {// 重写线程的run方法while (true) {try {Thread.sleep(1000);// 线程睡眠一秒钟} catch (Exception e) {// TODO: handle exception}Intent intent = new Intent();// 创建Intent对象intent.setAction("com.momo.componentcommunication.MainActivity");intent.putExtra("data", Math.random());// 以data为键，随机数为值sendBroadcast(intent);// 发送广播}}}.start();}/** *  * @author Administrator 继承于BroadcastReceiver的子类 * */private class CommandReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent) {// TODO Auto-generated method stubLog.i(TAG, "CommandReceiver:onReceive");/** 从 intent 对象中取出以“cmd”为键的值 */int cmd = intent.getIntExtra("cmd", -1);// 获取Extra信息/** 如果发来的消息是停止服务 */if (cmd == MainActivity.CMD_STOP_SERVICE) {flag = false;// 停止线程stopSelf();// 停止服务}}}}

布局文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="${relativePackage}.${activityClass}" >    <Button        android:id="@+id/btnStart"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="开启服务" />    <Button        android:id="@+id/btnStop"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_below="@+id/btnStart"        android:text="停止服务" />    <TextView        android:id="@+id/txtShow"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_alignParentLeft="true"        android:layout_below="@+id/btnStop"        android:layout_marginTop="42dp"        android:padding="20dip"        android:text="等待接收来自Service的数据" /></RelativeLayout>

配置文件：

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.momo.componentcommunication"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="16" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <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=".RandomService" android:process=":remote" ><intent-filter><action android:name="com.momo.componentcommunication.RandomService.STOPACTION"/></intent-filter></service>    </application></manifest>