Android中替换WebView加载网页失败时的页面

package com.example.webview;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
public class MainActivity extends AppCompatActivity {
  private WebView webview;
  private WebSettings mWebSettings;
  private View mErrorView;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    webview = (WebView) findViewById(R.id.main_webview);
    setUpView();
  }
  private void setUpView() {
    //加载需要显示的网页
    webview.loadUrl("http://www.baidu.com/");
    //设置WebView属性，能够执行Javascript脚本
    webview.getSettings().setJavaScriptEnabled(true);
    mWebSettings = webview.getSettings();
    mWebSettings.setJavaScriptEnabled(true);  //允许加载javascript
    mWebSettings.setSupportZoom(true);     //允许缩放
    mWebSettings.setBuiltInZoomControls(true); //原网页基础上缩放
    mWebSettings.setUseWideViewPort(true);   //任意比例缩放
    webview.setWebViewClient(webClient); //设置Web视图
  }
  /***
   * 设置Web视图的方法
   */
  WebViewClient webClient = new WebViewClient(){//处理网页加载失败时
    public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
      showErrorPage();//显示错误页面
    };
  };
  boolean mIsErrorPage;
  protected void showErrorPage() {
    LinearLayout webParentView = (LinearLayout)webview.getParent();
    initErrorPage();//初始化自定义页面
    while (webParentView.getChildCount() > 1) {
      webParentView.removeViewAt(0);
    }
    @SuppressWarnings("deprecation")
    LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(ViewPager.LayoutParams.FILL_PARENT, ViewPager.LayoutParams.FILL_PARENT);
    webParentView.addView(mErrorView, 0, lp);
    mIsErrorPage = true;
  }
  /****
   * 把系统自身请求失败时的网页隐藏
   */
  protected void hideErrorPage() {
    LinearLayout webParentView = (LinearLayout)webview.getParent();
    mIsErrorPage = false;
    while (webParentView.getChildCount() > 1) {
      webParentView.removeViewAt(0);
    }
  }
  /***
   * 显示加载失败时自定义的网页
   */
  protected void initErrorPage() {
    if (mErrorView == null) {
      mErrorView = View.inflate(this, R.layout.activity_error, null);
      RelativeLayout layout = (RelativeLayout)mErrorView.findViewById(R.id.online_error_btn_retry);
      layout.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
          webview.reload();
        }
      });
      mErrorView.setOnClickListener(null);
    }
  }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical"
  tools:context="com.example.webview.MainActivity">
  <WebView
    android:id="@+id/main_webview"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
  </WebView>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
  <RelativeLayout
    android:id="@+id/online_error_btn_retry"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#E6E6E6"
    android:clickable="true"
    android:gravity="center" >
    <LinearLayout
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:gravity="center"
      android:orientation="vertical"
      >
      <ImageView
        android:layout_width="70dp"
        android:layout_height="70dp"
        android:src="@drawable/wifi"
        android:id="@+id/imageView2" />
      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="18dp"
        android:text="数据获取失败"
        ></TextView>
      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="15dp"
        android:text="请检查网络后，点击重新加载"
        />
    </LinearLayout>
  </RelativeLayout>
</LinearLayout>