前言：
有時候在設計一個app時不只要考慮到功能還需要配合外觀才可以，而在搜尋網路時最常想到的就是讀取條了這篇就是結合上一篇並且做延伸，加上讀取條

第一步：在布局文件上加上讀取條物件

<ProgressBar
        android:id="@+id/progressbar"
        style="@android:style/Widget.ProgressBar.Horizontal"
        android:layout_width="match_parent"
        android:layout_height="3dip"
        android:max="100"
        android:progress="0"
        android:visibility="gone"/>

第二步：呼叫元件並且增加監聽系統

progressBar= findViewById(R.id.progressbar);
webView.addJavascriptInterface(this,"android");//添加js监听 这样html就能调用客户端
webView.setWebChromeClient(webChromeClient);

第三步：將監聽放進 Webiew 處理事件的地方

 private WebViewClient webViewClient=new WebViewClient(){
        @Override
        public void onPageFinished(WebView view, String url) {//页面加载完成
            progressBar.setVisibility(View.GONE);
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {//页面开始加载
            progressBar.setVisibility(View.VISIBLE);
        }

        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            Log.i("ansen","拦截url:"+url);
            if(url.equals("http://www.google.com/")){
                Toast.makeText(MainActivity.this,"国内不能访问google,拦截该url",Toast.LENGTH_LONG).show();
                return true;//表示我已经处理过了
            }
            return super.shouldOverrideUrlLoading(view, url);
        }

    };

第四步：創建 WebChromeClient 來處理Javascript的加載進度

private WebChromeClient webChromeClient=new WebChromeClient(){
//(此段可以不需要，是用來預防網頁跳出不支持 Javascript 的彈出視窗，所以需要自己監聽
        @Override
        public boolean onJsAlert(WebView webView, String url, String message, JsResult result) {
            AlertDialog.Builder localBuilder = new AlertDialog.Builder(webView.getContext());
            localBuilder.setMessage(message).setPositiveButton("确定",null);
            localBuilder.setCancelable(false);
            localBuilder.create().show();
            result.confirm();
            return true;
        }
        //獲取網頁標題
        @Override
        public void onReceivedTitle(WebView view, String title) {
            super.onReceivedTitle(view, title);
        }
//)
        
        //載入進度
        @Override
        public void onProgressChanged(WebView view, int newProgress) {
            progressBar.setProgress(newProgress);
        }
    };

以下為所有程式碼

package com.example.webview;
import android.app.AlertDialog;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.View;
import android.webkit.JavascriptInterface;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {
    private WebView webView;
    private ProgressBar progressBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        progressBar=findViewById(R.id.progressbar);
        webView =findViewById(R.id.webview);
        webView.loadUrl("https://www.google.com/?hl=zh_CN");

        webView.addJavascriptInterface(this,"android");
        webView.setWebChromeClient(webChromeClient);
        webView.setWebViewClient(webViewClient);

        WebSettings webSettings=webView.getSettings();
        webSettings.setJavaScriptEnabled(true);

        webSettings.setCacheMode(WebSettings.LOAD_NO_CACHE);
        webSettings.setSupportZoom(true);
        webSettings.setBuiltInZoomControls(true);
    }
    
    private WebViewClient webViewClient=new WebViewClient(){
        @Override
        public void onPageFinished(WebView view, String url) {
            progressBar.setVisibility(View.GONE);
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            progressBar.setVisibility(View.VISIBLE);
        }
    };
    
    private WebChromeClient webChromeClient=new WebChromeClient(){
        @Override
        public boolean onJsAlert(WebView webView, String url, String message, JsResult result) {
            AlertDialog.Builder localBuilder = new AlertDialog.Builder(webView.getContext());
            localBuilder.setMessage(message).setPositiveButton("确定",null);
            localBuilder.setCancelable(false);
            localBuilder.create().show();
            result.confirm();
            return true;
        }
        @Override
        public void onReceivedTitle(WebView view, String title) {
            super.onReceivedTitle(view, title);
        }
        @Override
        public void onProgressChanged(WebView view, int newProgress) {
            progressBar.setProgress(newProgress);
        }
    };

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (webView.canGoBack() && keyCode == KeyEvent.KEYCODE_BACK){
            webView.goBack(); 
            return true;
        }
        return super.onKeyDown(keyCode,event);
    }
    @JavascriptInterface 
    public void  getClient(String str){
        Log.i("ansen","html调用客户端:"+str);
    }
}