Android基礎------Broadcast基礎

 

廣播分爲普通廣播和有序廣播，廣播的註冊方式分爲動態註冊和靜態註冊

動態註冊廣播是在代碼中進行註冊，這種註冊方式下廣播的生命週期隨Activity，不一定同時創建，但是基本同時銷燬。動態註冊廣播的步驟爲：創建廣播接收者，創建過濾器、添加action、註冊廣播，發送廣播

靜態註冊廣播生命週期不受Activity的生命週期影響，這種註冊方式是在AndroidManifest.xml文件中進行配置。

普通廣播的註冊

package com.example.mybroadcast.registerbroadcast;

import androidx.appcompat.app.AppCompatActivity;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import com.example.mybroadcast.R;

/**
 * 動態註冊廣播，此註冊廣播的方式下，廣播的生命週期跟隨Activity，不一定同生，但一般共死
 */
public class DynamicRegisterActivity extends AppCompatActivity {

    private Button button;
    public static final String ACTION_TEST  = "com.example.mybroadcast.TEST";
    DynamicRegisterReceiver receiver;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dynamic_register);
        button = findViewById(R.id.btn_dynamic_register);
        receiver = new DynamicRegisterReceiver();
        /**
         * 定義過濾器，添加Action，註冊廣播
         */
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ACTION_TEST);
        registerReceiver(receiver,intentFilter);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //發送廣播
                Intent intent = new Intent();
                intent.setAction(ACTION_TEST);
                sendBroadcast(intent);
            }
        });
    }

    /**
     * 創建廣播接收者
     */
    class DynamicRegisterReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if(ACTION_TEST.equals(action)){
                Toast.makeText(context,"動態註冊廣播成功",Toast.LENGTH_SHORT).show();
            }
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        //註銷廣播
        if(receiver != null){
            unregisterReceiver(receiver);
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

   <Button
       android:id="@+id/btn_dynamic_register"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:textSize="20sp"
       android:text="動態註冊廣播"
       android:layout_centerInParent="true"/>

</RelativeLayout>

 

下面是靜態註冊廣播

package com.example.mybroadcast.registerbroadcast;

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

/**
 * 靜態註冊廣播，監聽開機
 * 監聽手機的開機事件需要在AndroidManifest.xml申請權限
 */
public class StaticRegisterReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        System.out.println("Action爲："+action);
        Toast.makeText(context,"開機了！！！！！",Toast.LENGTH_SHORT).show();

    }
}

AndroidManifest.xml文件

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

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

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".orderbroadcast.SendOrderBroadcast">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".registerbroadcast.DynamicRegisterActivity">

        </activity>

        <receiver android:name=".registerbroadcast.StaticRegisterReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
        
        <receiver android:name=".orderbroadcast.HighLevelReceiver">
            <!--     priority屬性設置廣播接收者的優先級，取值爲-1000～1000，數值越大優先級越高    -->
            <intent-filter android:priority="1000">
                <action android:name="com.example.mybroadcast.SEND_ORDER"/>
            </intent-filter>
        </receiver>
        <receiver android:name=".orderbroadcast.LowLevelReceiver">
            <intent-filter android:priority="-1000">
                <action android:name="com.example.mybroadcast.SEND_ORDER"/>
            </intent-filter>
        </receiver>
    </application>

</manifest>

 

有序廣播

有序廣播在註冊時要注意爲其設置優先級，有序廣播有終止廣播繼續傳遞的方法，有序廣播可以攜帶數據傳遞，有更改數據的方法。

package com.example.mybroadcast.orderbroadcast;

import androidx.appcompat.app.AppCompatActivity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import com.example.mybroadcast.R;

/**
 * 發送有序廣播
 */
public class SendOrderBroadcast extends AppCompatActivity {

    Button button;
    public static final String ACTION_SEND_ORDER = "com.example.mybroadcast.SEND_ORDER";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_send_order_broadcast);
        button = findViewById(R.id.btn_send_order);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setAction(ACTION_SEND_ORDER);
                Bundle bundle = new Bundle();
                bundle.putCharSequence("msg","這是一個有序廣播");
                intent.putExtras(bundle);
                sendOrderedBroadcast(intent,null,null,null, Activity.RESULT_OK,null,bundle);
            }
        });
    }
}

 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".orderbroadcast.SendOrderBroadcast">

    <Button
        android:id="@+id/btn_send_order"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="發送有序廣播"/>

</LinearLayout>

package com.example.mybroadcast.orderbroadcast;

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

/**
 * 優先級高的廣播接收者
 */
public class HighLevelReceiver extends BroadcastReceiver {
    private static final String TAG = "HighLevelReceiver：";

    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = getResultExtras(true);
        String msg = bundle.getCharSequence("msg").toString();
        Log.d(TAG,msg);
        /**
         * abortBroadcast();此方法可以終止有序廣播繼續往下傳播
         */
        abortBroadcast();
        //設置信息並將信息再放入廣播中
        bundle.putCharSequence("msg","信息已經改變");
        setResultExtras(bundle);
    }
}

package com.example.mybroadcast.orderbroadcast;

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

/**
 * 優先級低的廣播接收者
 */
public class LowLevelReceiver extends BroadcastReceiver {
    private static final String TAG = "LowLevelReceiver：";

    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = getResultExtras(true);
        String msg = bundle.getCharSequence("msg").toString();
        Log.d(TAG,msg);
    }
}

 

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