Android四大组件之广播接收者（BroadcastReceiver）

广播接收者简介：
为了监听来自系统或应用程序的广播事件，Android系统提供了BroadcastReceiver（广播接收者）组件。
广播接收者创建：
右击—-包名—-new—-Other—-Broadcast Receiver—-名字自取、其他默认

默认：继承BroadcastReceiver类，重写onReceive()方法

public class MyReceiver extends BroadcastReceiver {
    public MyReceiver() {
    }
    @Override
    public void onReceive(Context context, Intent intent) {
         throw new UnsupportedOperationException("Not yet implemented");
        }
    }

静态注册（自动）：

<?xml version="1.0" encoding="utf-8"?>
<manifest ......>
    <application ......>
        <receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">           
        </receiver>       
    </application>
</manifest>

enabled:用于选择广播接收者是否可以由系统实例化
exported:用于选择是否接受当前程序之外的广播

动态注册：

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        MyReceiver receiver=new MyReceiver();
        String action="android.provider.Telephoto.SMS_RECEIVED";
        IntentFilter intentFilter=new IntentFilter(action);
        registerReceiver(receiver,intentFilter);
    }
    protected void onDestroy()
    {
        super.onDestroy();
        unregisterReceiver(receiver);
    }

案例：拦截电话
activity_main.xml：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/sdz"
    android:padding="15dp"
    tools:context="cn.edu.bzu.myapplication.MainActivity">

    <EditText
        android:id="@+id/et_ipnumber"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:hint="请输入拦截号码" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/et_ipnumber"
        android:layout_centerHorizontal="true"
        android:background="#ACD6FF"
        android:onClick="click"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"
        android:text="保存拦截号码"
        android:textSize="16sp" />
</RelativeLayout>

MainActivity：点击保存拦截号码按钮时事件处理

package cn.edu.bzu.myapplication;

import android.content.SharedPreferences;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    private EditText et_ipnumber;
    private SharedPreferences sp;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        et_ipnumber = (EditText) findViewById(R.id.et_ipnumber);
        //创建SharedPreferences对象
        sp = getSharedPreferences("config", MODE_PRIVATE);
    }

    public void click(View view) {
        //获取用户输入的拦截号码
        String number = et_ipnumber.getText().toString().trim();
        //创建Editor对象，保存用户输入的拦截号码
        SharedPreferences.Editor editor = sp.edit();
        editor.putString("number", number);
        editor.commit();
        Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
    }
}

MyReceiver：创建广播接收者MyReceiver

package cn.edu.bzu.myapplication;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;

public class MyReceiver extends BroadcastReceiver {
    public MyReceiver() {
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        //获取拨打的电话号码
        String outcallnumber = getResultData();
        //创建SharedPreferences对象，获取拦截号码
        SharedPreferences sp = context.getSharedPreferences("config", Context.MODE_PRIVATE);
        String number = sp.getString("number", "");
        //判断是否是拦截电话号码
        if (outcallnumber.equals("number")) {
            //清楚电话
            setResultData(null);
        }
    }
}

注册广播接受者：

<?xml version="1.0" encoding="utf-8"?>
<manifest ......>
    <application ......>
        <receiver
            android:name=".MyReceiver"
            android:enabled="true"
            android:exported="true">   
             <intent-filter>
                <action android:name="android.intent.action.NEW_OUTGOING_CALL" />
            </intent-filter>        
        </receiver>       
    </application>
    <uses-permission android:name="android.permission.PROCESS_OUTGOING_CALLS" />
</manifest>

：广播接收者对应的动作。意图过滤器，电话播出的过滤器。
:权限设置