android编程5.2.1

alltolove

先新建一个项目，修改androidmanifest.xml文件，在manifest标签里添加

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

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修改activity_main.xml文件

1. <?xml version="1.0" encoding="utf-8"?>
   
2. <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
   
3.     xmlns:app="http://schemas.android.com/apk/res-auto"
   
4.     xmlns:tools="http://schemas.android.com/tools"
   
5.     android:layout_width="match_parent"
   
6.     android:layout_height="match_parent"
   
7.     tools:context="com.example.xinwei.broadcasttest.MainActivity">
   
8. 
   
9.     <TextView
   
10.         android:id="@+id/text"
    
11.         android:layout_width="wrap_content"
    
12.         android:layout_height="wrap_content"
    
13.         android:text="Hello World!"
    
14.         app:layout_constraintBottom_toBottomOf="parent"
    
15.         app:layout_constraintLeft_toLeftOf="parent"
    
16.         app:layout_constraintRight_toRightOf="parent"
    
17.         app:layout_constraintTop_toTopOf="parent" />
    
18. 
    
19. </android.support.constraint.ConstraintLayout>
    

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修改mainactivity.java文件

1. package com.example.xinwei.broadcasttest;
   
2. 
   
3. import android.content.BroadcastReceiver;
   
4. import android.content.Context;
   
5. import android.content.Intent;
   
6. import android.content.IntentFilter;
   
7. import android.net.ConnectivityManager;
   
8. import android.net.NetworkInfo;
   
9. import android.support.v7.app.AppCompatActivity;
   
10. import android.os.Bundle;
    
11. import android.widget.TextView;
    
12. import android.widget.Toast;
    
13. 
    
14. public class MainActivity extends AppCompatActivity {
    
15.     private IntentFilter intentFilter;
    
16.     NetworkChangeReceiver networkChangeReceiver;
    
17.     TextView text;
    
18.     @Override
    
19.     protected void onCreate(Bundle savedInstanceState) {
    
20.         super.onCreate(savedInstanceState);
    
21.         setContentView(R.layout.activity_main);
    
22.         intentFilter=new IntentFilter();
    
23.         intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
    
24.         networkChangeReceiver=new NetworkChangeReceiver();
    
25.         registerReceiver(networkChangeReceiver,intentFilter);
    
26.     }
    
27. 
    
28.     @Override
    
29.     protected void onDestroy() {
    
30.         super.onDestroy();
    
31.         unregisterReceiver(networkChangeReceiver);
    
32.     }
    
33. 
    
34.     class NetworkChangeReceiver extends BroadcastReceiver{
    
35. 
    
36.         @Override
    
37.         public void onReceive(Context context, Intent intent) {
    
38.             ConnectivityManager connectivityManager=(ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    
39.             NetworkInfo networkInfo=connectivityManager.getActiveNetworkInfo();
    
40.             if(networkInfo!=null&&networkInfo.isAvailable()){
    
41.                 text=(TextView)findViewById(R.id.text);
    
42.                 text.setText("有网");
    
43.             }
    
44.         }
    
45.     }
    
46. }
    

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效果图为：