一天一點android知識（Broadcast）

android開發的廣播技術包括兩種廣播：Normal and Ordered broadcasts。在标準廣播中所有接收器享受同等待遇，而在有序廣播中類似于鍊式傳播，各個接收器有先後順序且能阻止廣播繼續傳播。另外為了程式和資料的安全考慮Android引入了一套本地廣播機制，使得廣播的發送和接收僅限于本程式，防止關鍵敏感資料洩露！

Project: Broadcasttest

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_height="match_parent"
    android:layout_width="match_parent">
    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Send Broadcast" />
</LinearLayout>
           

MainActivity,java

package com.example.broadcasttest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.support.v4.content.LocalBroadcastManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private IntentFilter intentFilter;

    private LocalReceiver localReceiver;

    private LocalBroadcastManager localBroadcastManager;

    //private NetworkChangeReceiver networkChangeReceiver;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        /* intentFilter = new IntentFilter();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        networkChangeReceiver = new NetworkChangeReceiver();
        registerReceiver(networkChangeReceiver,intentFilter);  */

        localBroadcastManager = localBroadcastManager.getInstance(this);

        Button button =(Button)findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                Intent intent = new Intent("com.example.broadcasttest.LOCAL_BROADCAST");
                localBroadcastManager.sendBroadcast(intent);
              //  Intent intent = new Intent("com.example.broadcasttest.MY_BROADCAST");
             //   sendBroadcast(intent);
              //  sendOrderedBroadcast(intent,null);
            }
        });

        intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.broadcasttest.LOCAL_BROADCAST");
        localReceiver = new LocalReceiver();
        localBroadcastManager.registerReceiver(localReceiver,intentFilter);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
     //   unregisterReceiver(networkChangeReceiver);
        localBroadcastManager.unregisterReceiver(localReceiver);
    }

    class NetworkChangeReceiver extends BroadcastReceiver{
        public void onReceive(Context context, Intent intent){
           // Toast.makeText(context,"network changes",Toast.LENGTH_SHORT).show();
            ConnectivityManager connectivityManager = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
            if(networkInfo!=null&&networkInfo.isAvailable()){
                Toast.makeText(context,"network is available",Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(context,"network is unavailable",Toast.LENGTH_SHORT ).show();
            }
        }
    }
}
           

BootCompleteReceiver

package com.example.broadcasttest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

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

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
    //    throw new UnsupportedOperationException("Not yet implemented");
        Toast.makeText(context,"Boot Complete",Toast.LENGTH_LONG).show();
    }
}
           

LocalReceiver.java

package com.example.broadcasttest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

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

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
       // throw new UnsupportedOperationException("Not yet implemented");
        Toast.makeText(context,"received local broadcast",Toast.LENGTH_SHORT).show();
    }
}
           

MyBroadcastReceiver.java

package com.example.broadcasttest;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

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

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
       // throw new UnsupportedOperationException("Not yet implemented");
        Toast.makeText(context,"received in MyBroadcastReceiver",Toast.LENGTH_SHORT).show();
        abortBroadcast();
    }
}
           

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.broadcasttest">

    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver
            android:name=".BootCompleteReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
        <receiver
            android:name=".MyBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter android:priority="100">
                <action android:name="com.example.broadcasttest.MY_BROADCAST" />
            </intent-filter>
        </receiver>
        <receiver
            android:name=".LocalReceiver"
            android:enabled="true"
            android:exported="true"></receiver>
    </application>

</manifest>
           

Project :Broadcasttest2

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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.broadcasttest2.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />
</RelativeLayout>
           

AnotherBroadcastReceiver.java

package com.example.broadcasttest2;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

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

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.
        //throw new UnsupportedOperationException("Not yet implemented");
        Toast.makeText(context,"received in AnotherBroadcastReceiver",Toast.LENGTH_SHORT).show();
    }
}
           

MainActivity.java

package com.example.broadcasttest2;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}
           

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.broadcasttest2">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver
            android:name=".AnotherBroadcastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="com.example.broadcasttest.MY_BROADCAST"/>
            </intent-filter>
        </receiver>
    </application>

</manifest>