BroadcastReceiver 总是与网络断开连接

Posted 2023-02-23

【中文标题】BroadcastReceiver 总是与网络断开连接

【英文标题】：BroadcastReceiver always get disconnected from network

【发布时间】：2016-09-07 08:21:21

【问题描述】：

我关注了android Developers tutorial Managing Network Usage。 似乎BroadcastReceiver 总是与网络断开连接。 我尝试通过AVD 和通过ADB 连接的电话运行我的应用程序，但两者都不起作用。 我也下载了示例，只是复制粘贴进行检查，但似乎有一个错误。 我留下了代码，但在网站上是一样的。

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.webkit.WebView;
import android.widget.Toast;

import org.xmlpull.v1.XmlPullParserException;

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.List;

public class NetworkActivity extends Activity 

    public static final String WIFI = "Wi-Fi";
    public static final String ANY = "Any";
    private static final String FEED_URL = "http://formulapassion.it/feed";

    private static boolean wifiConnected = false;
    private static boolean mobileConnected = false;
    public static boolean refreshDisplay = true;

    public static String sPref = null;

    private NetworkReceiver receiver = new NetworkReceiver();

    @Override
    public void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);

        // Filter added dinamically
        IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
        receiver = new NetworkReceiver();
        this.registerReceiver(receiver, filter);
    

    @Override
    public void onStart() 
        super.onStart();

        SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
        sPref = sharedPrefs.getString("listPref", "Wi-Fi");

        updateConnectedFlags();

        if (refreshDisplay) 
            loadPage();
        
    

    @Override
    public void onDestroy() 
        super.onDestroy();
        if (receiver != null) 
            this.unregisterReceiver(receiver);
        
    

    private void updateConnectedFlags() 
        ConnectivityManager connMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();
        if (activeInfo != null && activeInfo.isConnected()) 
            wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
            mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;
         else 
            wifiConnected = false;
            mobileConnected = false;
        
    

    private void loadPage() 
        if (((sPref.equals(ANY)) && (wifiConnected || mobileConnected))
                || ((sPref.equals(WIFI)) && (wifiConnected))) 
            new DownloadXmlTask().execute(FEED_URL);
        
        else 
            showErrorPage();
        
    

    private void showErrorPage() 
        setContentView(R.layout.news_feed_webview);

        // The specified network connection is not available. Displays error message.
        WebView myWebView = (WebView) findViewById(R.id.main_webview);
        myWebView.loadData("Errore! Nessuna connessione",
                "text/html", null);
    

    private class DownloadXmlTask extends AsyncTask<String, Void, String> 
                /* */
    

    private String loadXmlFromNetwork(String urlString) throws XmlPullParserException, IOException 
                /* */
    

    public class NetworkReceiver extends BroadcastReceiver 

        @Override
        public void onReceive(Context context, Intent intent) 
            ConnectivityManager connMgr =
                    (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
            NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

            if (WIFI.equals(sPref) && networkInfo != null
                    && networkInfo.getType() == ConnectivityManager.TYPE_WIFI) 
                refreshDisplay = true;
                Toast.makeText(context, "Connesso", Toast.LENGTH_SHORT).show();
             else if (ANY.equals(sPref) && networkInfo != null) 
                refreshDisplay = true;
             else 
                refreshDisplay = false;
                Toast.makeText(context, "Disconnesso", Toast.LENGTH_SHORT).show();
            

        
    

还有我的Manifest：

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

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

    <uses-sdk xmlns:tools="http://schemas.android.com/tools"
        tools:overrideLibrary="android.support.v14.preference,android.support.v7.appcompat,android.support.v7.preference,android.support.graphics.drawable,android.support.compat,android.support.v4,android.support.coreutils,android.support.mediacompat,android.support.coreui,android.support.fragment,android.support.v7.recyclerview" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.MyCustomTheme.Light" >
     <!--   android:theme="@style/Theme.AppCompat.Light"> -->

        <activity
            android:name=".MainActivity" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

        <activity
            android:name=".FirstTimeActivity"
            android:theme="@style/Theme.AppCompat.NoActionBar" />

        <receiver android:name=".NetworkActivity$NetworkReceiver">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
            </intent-filter>
        </receiver>

        <activity
            android:name=".SettingsActivity"
            android:parentActivityName=".MainActivity" >
                <action android:name="android.intent.action.MANAGE_NETWORK_USAGE" />
                <category android:name="android.intent.category.DEFAULT" />
        </activity>

        <activity android:name=".NetworkActivity">
        </activity>

    </application>

</manifest>

【参考方案1】：

如果您连接到 WiFi，则需要添加 WiFi 状态更改侦听器操作，如下所示：

<receiver android:name=".NetworkActivity$NetworkReceiver">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
                <action android:name="android.net.wifi.WIFI_STATE_CHANGED" />
            </intent-filter>
</receiver> 

【讨论】：

对不起，还是一样，总是断线。