如果未连接到互联网，则要求用户在启动 Android 应用程序时启动 WiFi 或 3G

我正在使用一个使用 WebView 访问一些在线页面的 Android 应用程序。我想添加一个选项，如果用户未连接到互联网，应用程序将提示打开 WiFi 或 3G。

实现这种用户便利性的最佳方式是什么？

代码如下：

package com.url.appname;


import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.Window;
import android.webkit.ValueCallback;
import android.webkit.WebView;
import android.webkit.WebChromeClient;
import android.webkit.WebViewClient;
import android.widget.Toast;

public class MainActivity extends Activity {

 private WebView wv;  


 private ValueCallback<Uri> mUploadMessage;  
 private final static int FILECHOOSER_RESULTCODE=1;

 @Override  
 protected void onActivityResult(int requestCode, int resultCode,  
                                    Intent intent) {  
  if(requestCode==FILECHOOSER_RESULTCODE)  
  {  
   if (null == mUploadMessage) return;  
            Uri result = intent == null || resultCode != RESULT_OK ? null  
                    : intent.getData();  
            mUploadMessage.onReceiveValue(result);  
            mUploadMessage = null;        
  }  
 }  

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    wv = new WebView(this);
//    wv = (WebView) findViewById(R.id.webview);
    wv.loadUrl("http://www.url.com");



    // Let's display the progress in the activity title bar, like the
    // browser app does.
    getWindow().requestFeature(Window.FEATURE_PROGRESS);

    wv.getSettings().setJavaScriptEnabled(true);

    final Activity activity = this;

    wv.setWebViewClient(new WebViewClient(){    

       public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
             Toast.makeText(activity, "Oh no! " + description, Toast.LENGTH_SHORT).show();
           }
         });

    wv.setWebChromeClient(new WebChromeClient()  {  

           public void onProgressChanged(WebView view, int progress) {
                 // Activities and WebViews measure progress with different scales.
                 // The progress meter will automatically disappear when we reach 100%
                 activity.setProgress(progress * 100);
               }

        // For Android 3.0+
        public void openFileChooser( ValueCallback<Uri> uploadMsg, String acceptType ) {  
            mUploadMessage = uploadMsg;  
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);  
            i.addCategory(Intent.CATEGORY_OPENABLE);  
            i.setType("image/*");  
            MainActivity.this.startActivityForResult( Intent.createChooser( i, "File Chooser" ), MainActivity.FILECHOOSER_RESULTCODE ); 
            }

        // For Android < 3.0
        public void openFileChooser( ValueCallback<Uri> uploadMsg ) {
            openFileChooser( uploadMsg, "" );
            }

        // For Android > 4.1
        public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture){
            openFileChooser( uploadMsg, "" );
            }

                                });
      setContentView(wv);      

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

}e

创建一个AlertDialog如果没有网络连接来告诉用户并提示他们。

使用此代码作为示例...

protected void createNetErrorDialog() {

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("You need a network connection to use this application. Please turn on mobile network or Wi-Fi in Settings.")
        .setTitle("Unable to connect")
        .setCancelable(false)
        .setPositiveButton("Settings",
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                Intent i = new Intent(Settings.ACTION_WIRELESS_SETTINGS);
                startActivity(i);
            }
        }
    )
    .setNegativeButton("Cancel",
        new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
                MyActivity.this.finish();
            }
        }
    );
    AlertDialog alert = builder.create();
    alert.show();
}

创建一个Intent with Settings.ACTION_WIRELESS_SETTINGS作为一个操作将启动网络设置的内置活动。