android:usesCleartextTraffic="true"

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.a99.myapplication">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme"
        android:usesCleartextTraffic="true"
        >

        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@style/AppTheme.NoActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
</manifest>

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.a99.myapplication.MainActivity">

    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:theme="@style/AppTheme.AppBarOverlay">


        <WebView
            android:id="@+id/webView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"></WebView>

    </android.support.design.widget.AppBarLayout>




</android.support.design.widget.CoordinatorLayout>

package com.example.a99.myapplication;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;

import android.graphics.Bitmap;
import android.util.Log;
import android.webkit.WebResourceRequest;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.Button;


public class MainActivity extends AppCompatActivity {

    public String url = "http://192.168.137.179:8080/";
    public WebView webView;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //1 创建网页打开使用
        webView = (WebView) findViewById(R.id.webView);
        webView.getSettings().setJavaScriptEnabled(true);//设置webview内可执行js脚本
        webView.getSettings().setDomStorageEnabled(true);//设置webview可存储dom缓存数据
        webView.loadUrl(url);
        //2 为了保证网页中连接打开网页
        webView.setWebViewClient(new MyWebViewClient());

    }

      //2 为了保证网页中连接打开网页
    class MyWebViewClient extends WebViewClient{
        @Override  //WebView代表是当前的WebView
        public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request) {
            //表示在当前的WebView继续打开网页
            view.loadUrl(request.getUrl().toString());

            return true;
        }
          //2 为了保证网页中连接打开网页
        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            Log.d("WebView","开始访问网页");
        }
          //2 为了保证网页中连接打开网页
        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
           Log.d("WebView","访问网页结束");
        }
    }



}

      repositories {
            maven { url ‘https://maven.google.com‘ }
            maven { url ‘https://repo1.maven.org/maven2‘ }
            jcenter { url "https://jcenter.bintray.com/" }
        }