Android WebView 加载网页遇到的问题

package com.example.yubai8.hybrid_app;

import android.os.Build;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }
    private WebView webView;
    private void init(){

        webView = (WebView) findViewById(R.id.webView);

        //这个主要解决加载网页不跳转到系统浏览器
        webView.setWebViewClient(new WebViewClient());


        //解决webview缓存问题
        if (Build.VERSION.SDK_INT >= 19) {
            webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
        }

        //WebView加载web资源
        webView.loadUrl("http://baidu.com");
    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.yubai8.hybrid_app.MainActivity">



    <WebView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/webView"
        />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.yubai8.hybrid_app">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        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>
    </application>
    <!--开启网络请求-->
    <uses-permission android:name="android.permission.INTERNET"/>
</manifest>

//这个主要解决加载网页不跳转到系统浏览器
webView.setWebViewClient(new WebViewClient());

//解决webview缓存问题
if (Build.VERSION.SDK_INT >= 19) {
    webView.getSettings().setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
}