Java 在mainactivity中声明接收者

我有一个声明为MainActivity.java的webView

import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity
{
    public static WebView webView;
    WebView webView = (WebView) findViewById(R.id.webview);        
    webView.postUrl(url, postData.getBytes());
}

接收器处理连接更改BroadcastReceiver.java

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class ConnectionBroadReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        ConnectivityManager cm = (ConnectivityManager)
                context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo netInfo = cm.getActiveNetworkInfo();

        if (netInfo != null && netInfo.isConnectedOrConnecting()) {
            MainActivity.webView.reload();
        } else {
            MainActivity.webView.reload();
        }    
    }
}

清单AndroidManifest.xml

<application
        android:allowBackup="true"
        android:icon="@drawable/logo_full"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver
            android:name=".ConnectionBroadReceiver">
            <intent-filter>
                <action android:name="android.net.conn.CONNECTIVITY_CHANGE"/>
            </intent-filter>
        </receiver>
    </application>

因为webView是一个公共静态webView webView；我无法从另一个类调用虚拟方法

onBroadReceiver:java.lang.NullPointerException:尝试调用 空对象上的虚拟方法“void android.webkit.WebView.reload” 参考文献

我该怎么做？

不要在清单中注册接收者，而是在活动中注册接收者，并通过接口在网络状态更改时进行交互

NetworkCallback.java

ConnectionBroadReceiver.java

现在在你的脑海里

public class MainActivity extends AppCompatActivity
{
    private WebView webView;

   public void onCreate(Bundle savedInstanceState){
    // you code to set content view
    webView = (WebView) findViewById(R.id.webview);        
    webView.postUrl(url, postData.getBytes());
    registerReceiver(new ConnectionBroadReceiver(new NetworkCallback(){
          @Override
          public void onStateChange(){
               webview.reload();
          }
     }),new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE")); 
  }
}

---

您不必将WebView设置为静态，就可以复制。您可以向活动广播另一条消息并处理连接更改。我有一些语法错误，你能检查一下吗？我真的不知道我必须在哪里添加android.net.conn.CONNECTIVITY\u更改答案中a之前有一个}，所以我不知道如何注册接收者……谢谢^^但局部变量webView是从内部类访问的；需要宣布为finalglad我可以帮助：

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public class ConnectionBroadReceiver extends BroadcastReceiver {
   private NetworkCallback callback;

    public ConnectionBroadReceiver(NetworkCallback callback){
          this.callback = callback;
    }

    @Override
    public void onReceive(Context context, Intent intent) {

        ConnectivityManager cm = (ConnectivityManager)
                context.getSystemService(Context.CONNECTIVITY_SERVICE);

        NetworkInfo netInfo = cm.getActiveNetworkInfo();

        if (netInfo != null && netInfo.isConnectedOrConnecting()) {
            callback.onStateChange();
        } else {
             callback.onStateChange();
        }    
    }
}

public class MainActivity extends AppCompatActivity
{
    private WebView webView;

   public void onCreate(Bundle savedInstanceState){
    // you code to set content view
    webView = (WebView) findViewById(R.id.webview);        
    webView.postUrl(url, postData.getBytes());
    registerReceiver(new ConnectionBroadReceiver(new NetworkCallback(){
          @Override
          public void onStateChange(){
               webview.reload();
          }
     }),new IntentFilter("android.net.conn.CONNECTIVITY_CHANGE")); 
  }
}