四大组件之BroadcastReceiver

╰+攻爆jí腚メ 2022-09-25 12:21 165阅读 0赞

组件篇BroadcastReceiver:

普通广播的特点：

同级别接收是随机的（无序的）

级别低的后收到广播

接收器不能截断广播的继续传播也不能处理广播

同级别动态注册高于静态注册

package com.example.broadcastrecieverdemo;
    
    import android.app.Activity;
    import android.content.Intent;
    import android.content.IntentFilter;
    import android.os.Bundle;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    
    
    public class MainActivity extends Activity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //动态注册
            IntentFilter intentFilter=new IntentFilter("BC_action");
            BC2 bc2=new BC2();
            registerReceiver(bc2,intentFilter);
        }
        public void doClick(View view){
        	switch (view.getId()) {
    		case R.id.send_btn:
    			Intent intent =new Intent();
    			intent.putExtra("msg","这是一条普通广播");
    			intent.setAction("BC_action");
    			sendBroadcast(intent);
    			break;
    
    		default:
    			break;
    		}
        }
    }

package com.example.broadcastrecieverdemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    
    public class BC1 extends BroadcastReceiver{
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		// TODO Auto-generated method stub
    		String s=intent.getStringExtra("msg");
    		System.out.println("receiver1收到消息："+s);
    	}
    
    }

package com.example.broadcastrecieverdemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    
    public class BC2 extends BroadcastReceiver{
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		// TODO Auto-generated method stub
    		String s=intent.getStringExtra("msg");
    		System.out.println("receiver2收到消息："+s);
    	}
    
    }

<receiver 
                android:name="com.example.broadcastrecieverdemo.BC1"
                >
                <intent-filter 
                    android:priority="100"
                    >
                    <action 
                        android:name="BC_action"
                        />
                </intent-filter>
            </receiver>

有序广播的特点：

同级别接受顺序是随机的

能截断广播的继续传播，高级别的广播接收器收到该广播后可以决定是否把该广播截断

接收器能截断广播的继续传播，也能处理广播

package com.example.broadcastrecieverdemo;
    
    import android.app.Activity;
    import android.content.Intent;
    import android.content.IntentFilter;
    import android.os.Bundle;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    
    
    public class MainActivity extends Activity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            //动态注册
    //        IntentFilter intentFilter=new IntentFilter("BC_action");
    //        BC2 bc2=new BC2();
    //        registerReceiver(bc2,intentFilter);
        }
        public void doClick(View view){
        	switch (view.getId()) {
    		case R.id.send_btn:
    			Intent intent =new Intent();
    			intent.putExtra("msg","这是一条普通广播");
    			intent.setAction("BC_action");
    			sendBroadcast(intent);
    			break;
    		case R.id.send_btn1:
    			Intent intent1 =new Intent();
    			intent1.putExtra("msg","这是一条有序广播");
    			intent1.setAction("BC_action");
    			sendOrderedBroadcast(intent1,null);
    			break;
    		default:
    			break;
    		}
        }
    }

package com.example.broadcastrecieverdemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.os.Bundle;
    
    public class BC1 extends BroadcastReceiver{
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		// TODO Auto-generated method stub
    		String s=intent.getStringExtra("msg");
    		System.out.println("receiver1收到消息："+s);
    		//终止广播
    		//abortBroadcast();
    		Bundle bundle=new Bundle();
    		bundle.putString("test", "广播处理数据");
    		setResultExtras(bundle);
    	}
    
    }

package com.example.broadcastrecieverdemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.os.Bundle;
    
    public class BC2 extends BroadcastReceiver{
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		// TODO Auto-generated method stub
    		String s=intent.getStringExtra("msg");
    		System.out.println("receiver2收到消息："+s);
    		Bundle bundle=getResultExtras(true);
    		String s2=bundle.getString("test");
    		System.out.println("得到的结果是："+s2);
    	}
    
    }

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.example.broadcastrecieverdemo"
        android:versionCode="1"
        android:versionName="1.0" >
    
        <uses-sdk
            android:minSdkVersion="15"
            android:targetSdkVersion="20" />
    
        <application
            android:allowBackup="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name"
            android:theme="@style/AppTheme" >
            <activity
                android:name=".MainActivity"
                android:label="@string/app_name" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
    
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
         
            <receiver 
                android:name="com.example.broadcastrecieverdemo.BC1"
                >
                <intent-filter >
                    <action 
                        android:name="BC_action"
                        />
                </intent-filter>
            </receiver>
             <receiver 
                android:name="com.example.broadcastrecieverdemo.BC2"
                >
                <intent-filter >
                    <action 
                        android:name="BC_action"
                        />
                </intent-filter>
            </receiver>
        </application>
    
    </manifest>

异步广播：

不能将处理结果传给下一个接受着，无法终止广播

bc3为全局变量；

Intent intent2 =new Intent();
    			intent2.putExtra("msg","这是一条有序广播");
    			intent2.setAction("BC_3");
    			sendStickyBroadcast(intent2);
    			IntentFilter intentFilter=new IntentFilter("BC_3");
    			bc3=new BC3();
    			registerReceiver(bc3,intentFilter);

package com.example.broadcastrecieverdemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    
    public class BC3 extends BroadcastReceiver{
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		// TODO Auto-generated method stub
    		System.out.println("接收到了异步广播");
    	}
    
    }

注：

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

动态注册需要卸载掉：

protected void onDestroy() {
        	// TODO Auto-generated method stub
        	super.onDestroy();
        	unregisterReceiver(bc3);
        	System.err.println("123");
        }