在android webview中弹出用户身份验证窗口

我想访问

Webview

中受私有保护的url。当我在浏览器中浏览该url时，会显示一个带有用户名和密码字段的弹出窗口，但当我将该url放置在android

WebView

中时，该弹出窗口不会出现，请帮助我解决此问题

这是我的MainActivity.java

package com.code.developers.afghannews;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.webkit.WebChromeClient;
import android.webkit.WebView;

public class MainActivity extends AppCompatActivity {
WebView wb;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    wb = (WebView) findViewById(R.id.Hello_World);
    wb.getSettings().setJavaScriptCanOpenWindowsAutomatically(true);
    wb.getSettings().setJavaScriptEnabled(true);
    wb.getSettings().setDomStorageEnabled(true);
    wb.getSettings().setBuiltInZoomControls(true);
    wb.getSettings().setSupportZoom(true);
    wb.getSettings().setSupportMultipleWindows(true);
    final Context myApp = this;
    wb.setWebChromeClient(new WebChromeClient() {
        @Override
        public boolean onJsAlert(WebView view, String url, String message, final android.webkit.JsResult result) {
            new AlertDialog.Builder(myApp)
                    .setTitle("javaScript dialog")
                    .setMessage(message)
                    .setPositiveButton(android.R.string.ok,
                            new AlertDialog.OnClickListener() {
                                public void onClick(DialogInterface dialog, int which) {
                                    result.confirm();
                                }
                            })
                    .setCancelable(false)
                    .create()
                    .show();

            return true;
        }

        ;
    });

    wb.loadUrl("http://192.168.1.6/video.cgi");
}
}

xml是：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:showIn="@layout/activity_main" tools:context=".MainActivity">


<WebView android:id="@+id/Hello_World"
    android:layout_width="match_parent"
    android:layout_height="500dp"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_marginTop="10dp"/>
</RelativeLayout>