要求用户在启动Android应用程序时启动WiFi或3G，如果没有连接到Internet

Question

An android app that accesses some online pages using WebView is what I'm working with. I want to incorporate an option where, if the user is not connected to internet, the application will prompt to switch on WiFi or 3G.

What's the best way to achieve this user convenience point of view?

The code is given below:

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

Answer 1

Create an AlertDialog if there isn't a network connection to tell the user and prompt them.

Use this code as an example...

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();
}

Creating an Intent with Settings.ACTION_WIRELESS_SETTINGS as an action will start the built-in activity for the network settings.