Android代码之路:BroadcastReceiver初体验

BroadcastReceiver简介

BroadcastReceiver是Android四大嫡系组件之一。它的功能非常强大,专门应用于接收广播消息通知,提醒用户做出处理。比如低电量提醒、时区改变提醒、语言选项改变提醒……

Android中的广播事件有下面5种:

1.Normal Broadcast:普通广播
2.System Broadcast: 系统广播(如ACTION_BATTERY_LOW)
3.Ordered broadcast:有序广播
4.Sticky Broadcast:粘性广播(在 android 5.0中deprecated)
5.Local Broadcast:App应用内广播

如何注册广播

注册广播得方式有两种:
1.静态注册
即在清单文件中进行注册广播


    
        
    

2.动态注册
即在Java代码中注册广播

MyReceiver receiver=new MyReceiver();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.robinsyu");
如何发送广播

通过intent传递注册的Action,使用sendBroadcast方法发送广播

Intent intent=new Intent();
intent.setAction("com.robinsyu");
intent.putExtra("name","I love android");
sendBroadcast(intent);
如何接收广播

1.首先要写一个广播接收器类,该类从BroadcastReceiver继承。
2.在onReceive方法中编写处理广播的代码
3.注意不要忘记在AndroidManifest.xml注册

如果一个广播接收器需要处理多个广播,可以使用intent.getAction方法判断当前接收到的是哪一个广播。

if ("action1".equals(intent.getAction())){
    //TODO……

} else if("action2".equals(intent.getAction())){
    //TODO……
}

Demo1:有序广播与无序广播

【1】无序广播:所有的接收者都会接收事件,不可以被拦截和修改。
【2】有序广播:按照优先级向下传递,可以修改广播数据和终止广播事件。

这里介绍一个有序广播的例子
1.编写三个BroadcastReceiver子类并在AndroidManifest.xml文件注册
分别设置优先级为-1000(最低),0(中间),1000(最高)


    
    
        
    



    
    
        
    



    
    
        
    

2.在布局中添加一个按钮,设置其点击事件为发送有序广播

public void onClick(View view){
    switch (view.getId()){
        case R.id.btn_sendbroad:
            Intent intent=new Intent();
            intent.putExtra("msg","有序广播");
            intent.setAction("com.robinsyu");
            /**
             * @param permition:设置接收有序广播的条件,没有条件为null
             */
            sendOrderedBroadcast(intent,null);
            break;
    }
}

3.在onReceive方法中接收广播消息
MyBroadcast1.java

public class MyBroadcast1 extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,intent.getStringExtra("msg")+"MyBroadcast1",Toast.LENGTH_SHORT).show();
    }
}

MyBroadcast2.java

public class MyBroadcast2 extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,intent.getStringExtra("msg")+"MyBroadcast2",Toast.LENGTH_SHORT).show();
    }
}

MyBroadcast3.java

public class MyBroadcast3 extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(context,intent.getStringExtra("msg")+"MyBroadcast3",Toast.LENGTH_SHORT).show();
    }
}

Demo2:使用BroadcastReceiver获取短信内容

1.在AndroidManifest.xml文件中注册receiver


    
        
    

2.在AndroidManifest.xml文件中添加权限



3.java代码:

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.telephony.SmsMessage;
import android.util.Log;

public class ShortMessageReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = intent.getExtras();

        if (bundle != null){
            Object[] objArray = (Object[]) bundle.get("pdus");

            SmsMessage[] messages = new SmsMessage[objArray.length];
            for (int i=0; i

Demo3: 使用BroadCastReceiver拦截骚扰电话

1.在AndroidManifest.xml文件中注册receiver


    
        
    

2.在AndroidManifest.xml文件中声明权限


3.java代码:

import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.telephony.TelephonyManager;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class BlockCallReceiver extends BroadcastReceiver {
    private final static String BLACKLIST_NUMBER = "10086";

    @Override
    public void onReceive(Context context, Intent intent) {
        TelephonyManager tm = (TelephonyManager) context.getSystemService(Service.TELEPHONY_SERVICE);

        switch (tm.getCallState()) {
            case TelephonyManager.CALL_STATE_RINGING:
                String incomingNumber = intent.getStringExtra("incoming_number");
                if (BLACKLIST_NUMBER.equals(incomingNumber)) {
                    Class telephonyManagerClass = TelephonyManager.class;

                    try {
                        //使用Java反射获取getITelephony方法对应的Method对象
                        Method telephonyMethod = telephonyManagerClass.getDeclaredMethod("getITelephony", null);
                        telephonyMethod.setAccessible(true);
                        Object object = telephonyMethod.invoke(tm,null);
                        //使用Java反射技术获取与endCall方法对应的Method对象
                        Method endCallMethod = object.getClass().getMethod("endCall",null);
                        endCallMethod.setAccessible(true);
                        //调用endCall方法挂断电话
                        endCallMethod.invoke(object, null);
                    } catch (NoSuchMethodException e) {
                        e.printStackTrace();
                    } catch (InvocationTargetException e) {
                        e.printStackTrace();
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    }
                }
                break;
            default:
                break;
        }
    }
}

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