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广播接收者BroadCast的认识

BroadCast用于接收其他程序或者本身发出的系统级别的通知

分为标准广播和有序广播

又分为动态注册和静态注册

动态注册:

  首先新建一个类用于接收广播(即广播接收者)的类,该类继承BroadCatReceiver类,并且重写onReceiver方法,收到广播后的各种逻辑就是在该方法里面编写,在onCreate()方法里面回去IntentFilter实例,并且添加广播的指令,然后获取BroadCastReciver类的实例,然后利用registerReciver()方法进行广播的注册,

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        bt_BroadCast = (Button) findViewById(R.id.bt_BroadCast);
        bt_BroadCast.setOnClickListener(new MyOnclick());


        intentFilter = new IntentFilter();
        newBroadCast = new NewBroadCast();
        intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
        registerReceiver(广播对象,IntentFilter对象 );
    }

动态注册的广播一定要取消注册,即在onDestroy()方法中调用unregisterReceiver()方法取消注册

   @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(newBroadCast);
    }

 

静态注册:

静态注册就是新建类继承BroadCastReciver类,然后在该类的清单文件中中指定发送的命令,就是静态注册广播

 <receiver
            android:name=".MyBrpadCastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="指定发送的命令"/>
            </intent-filter>
        </receiver>

发送自定义广播:

  标准广播

    布局设计一个按钮,在按钮的点击事件中定义Intent并且发送出去,

public class MyOnclick implements View.OnClickListener {

        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.bt_BroadCast:
                    Intent intent = new Intent("ca.sd.zsl.broadcasttest.MY_BROADCAST");
            sendBroadcast(intent);//发送标准广播
            break; default: break; } } }

然后新建一个类MyBrpadCastReceiver继承BroadCastReciver,用于接收发送的广播,

不要忘记在清单文件中注册该广播

 <receiver
            android:name=".MyBrpadCastReceiver"
            android:enabled="true"
            android:exported="true">
            <intent-filter>
                <action android:name="ca.sd.zsl.broadcasttest.MY_BROADCAST"/>
            </intent-filter>
        </receiver>

 

发送有序广播:

  发送有序广播和发送标准广播的大体步骤是一样的,

唯一的区别在于发送有序广播的时候使用的是sendOrderedBroadcast(intent,null)方法,

 public class MyOnclick implements View.OnClickListener {

        @Override
        public void onClick(View view) {
            switch (view.getId()) {
                case R.id.bt_BroadCast:
                    Intent intent = new Intent("ca.sd.zsl.broadcasttest.MY_BROADCAST");
                    sendOrderedBroadcast(intent,null);//发送有序广播
                    break;
                default:
                    break;
            }
        }
    }

在发送有序广播时,可以在创建一个项目,并且新建类继承BroadCastReciver类,在清单文件中同样配置相同的action命令,即可接受相同的广播,

有序广播可以设置接收广播的的优先级,在清单文件中设置 android:priority="100"属性,数值越大,代表优先级越大,

  <receiver
            android:name=".AnotherBroadCastreciver"
            android:enabled="true"
            android:exported="true">
            <intent-filter android:priority="100">
                <action android:name="ca.sd.zsl.broadcasttest.MY_BROADCAST"/>
            </intent-filter>
        </receiver>

想要截断有序广播的传输,就在要截断的那个继承BroadCastReciver的类重写的方法onReciver()中最后添加一行代码abortBroadcast();

  @Override
    public void onReceive(Context context, Intent intent) {
        // 编写接受到广播后的操作逻辑结构
        abortBroadcast();//截断广播
    }

发送本地广播:

该程序发出的广播只能在程序内部进行传递,而且该广播接收器也只能接受来自本程序发出的广播,并且本地广播不能在清单文件中注册,发送方式和动态注册广播接收器以及发送广播是大体一样的,

  不过本地广播是通过LocalBroadcastManager.getInstance()方法得到一个实例,然后发送广播的时候调用 localBroadcastManager的sendBroadcast(intent)方法,然后取消注册广播的时候在调用localBroadcastManager的unregisterReceiver(localReciver)的方法。

  

package ca.sd.zsl.localbroadcastmanagetest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
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 {
    Button bt_local;
    private IntentFilter intentFilter;
    private LocalReciver localReciver;
    private LocalBroadcastManager localBroadcastManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        localBroadcastManager = LocalBroadcastManager.getInstance(this);//获取一个本地实例
        bt_local = (Button) findViewById(R.id.bt_local);
        bt_local.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent("ca.sd.zsl.LOCAL_BROADCAST");
                localBroadcastManager.sendBroadcast(intent);//发送本地广播
            }
        });
        intentFilter = new IntentFilter();
        intentFilter.addAction("ca.sd.zsl.LOCAL_BROADCAST");
        localReciver = new LocalReciver();
        localBroadcastManager.registerReceiver(localReciver, intentFilter);//注册本地广播件监听器

    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        localBroadcastManager.unregisterReceiver(localReciver);
    }

    public class LocalReciver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            Toast.makeText(context, "广播", Toast.LENGTH_SHORT).show();
        }
    }
}

 

广播接收者BroadCast的认识