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

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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
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> 



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posted @ 2010-01-21 09:07  webabcd  阅读(10486)  评论(22编辑  收藏  举报