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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 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 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 <? 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 >
                
                 < activity android:name =".MyActivity" android:label ="Activity 2" />
         application >
         < uses-sdk android:minSdkVersion ="3" />
manifest >     2、Service, Broadcast, BroadcastReceiver 的演示
Main.java 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 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 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 <? 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 >
                
                
                 < service android:name =".MyService" > service >
                
                
                 < receiver android:name =".MyBootReceiver" >
                         < intent-filter >
                                 < action android:name ="android.intent.action.BOOT_COMPLETED" />
                         intent-filter >
                 receiver >
         application >
        
        
         < uses-permission android:name ="android.permission.RECEIVE_BOOT_COMPLETED" />
         < uses-sdk android:minSdkVersion ="3" />
manifest >     OK
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