android webview加载assets目录中的html

 加载目录：

String url = "file:///android_asset/web/index.html";
 
webView.loadUrl(url);

完整代码:

package com.example.h5application;

import androidx.appcompat.app.AppCompatActivity;

import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.graphics.Bitmap;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.webkit.CookieManager;
import android.webkit.JsPromptResult;
import android.webkit.JsResult;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public class MainActivity extends AppCompatActivity {

    private WebView webView;
    String url = "file:///android_asset/web/index.html";

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        webView = new CustomWebView(this);
        WebSettings mWebSettings = webView.getSettings();

        CookieManager cookieManager = CookieManager.getInstance();
        cookieManager.setAcceptCookie(true);
        mWebSettings.setJavaScriptEnabled(true);//设置支持javaScript
        mWebSettings.setUseWideViewPort(true); //将图片调整到适合webview的大小
        mWebSettings.setLoadWithOverviewMode(true); // 缩放至屏幕的大小
        mWebSettings.setLayoutAlgorithm(WebSettings.LayoutAlgorithm.SINGLE_COLUMN);
        mWebSettings.setUserAgentString("User-Agent");
        mWebSettings.setLightTouchEnabled(true);//设置用鼠标激活被选项
        mWebSettings.setBuiltInZoomControls(true);//设置支持缩放
        mWebSettings.setDomStorageEnabled(true);//设置DOM缓存，当H5网页使用localStorage时，一定要设置
        mWebSettings.setDatabaseEnabled(true);
        mWebSettings.setCacheMode(WebSettings.LOAD_NO_CACHE);//设置去缓存，防止加载的为上一次加载过的
        mWebSettings.setSupportZoom(true);//设置支持变焦
        webView.setHapticFeedbackEnabled(false);
        mWebSettings.setPluginState(WebSettings.PluginState.ON);
        mWebSettings.setAllowFileAccess(true);
        mWebSettings.setAllowContentAccess(true);
        mWebSettings.setAllowUniversalAccessFromFileURLs(true);
        mWebSettings.setAllowFileAccessFromFileURLs(true);

        webView.setWebViewClient(new WebViewClient() {

            @Override
            public void onPageStarted(WebView view, String url, Bitmap favicon) {
                super.onPageStarted(view, url, favicon);
                Log.d("MainActivity","开始加载");
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                super.onPageFinished(view, url);
                Log.d("MainActivity","加载结束");
            }

            // 链接跳转都会走这个方法
            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                Log.d("MainActivity","Url："+ url );
                view.loadUrl(url);// 强制在当前 WebView 中加载 url
                return false;
            }
        });

        //设置响应js 的Alert()函数
        webView.setWebChromeClient(new WebChromeClient() {

            @Override
            public void onProgressChanged(WebView view, int newProgress) {
                super.onProgressChanged(view, newProgress);
                Log.d("MainActivity","newProgress："+ newProgress );
            }

            @Override
            public void onReceivedTitle(WebView view, String title) {
                super.onReceivedTitle(view, title);
                Log.d("MainActivity","标题："+ title);
            }

            @Override
            public boolean onJsAlert(WebView view, String url, String message, final JsResult result) {
                AlertDialog.Builder b = new AlertDialog.Builder(MainActivity.this);
                b.setTitle("");
                b.setMessage(message);
                b.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        result.confirm();
                    }
                });
                b.setCancelable(false);
                b.create().show();
                return true;
            }

            //设置响应js 的Confirm()函数
            @Override
            public boolean onJsConfirm(WebView view, String url, String message, final JsResult result) {
                AlertDialog.Builder b = new AlertDialog.Builder(MainActivity.this);
                b.setTitle("");
                b.setMessage(message);
                b.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        result.confirm();
                    }
                });
                b.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        result.cancel();
                    }
                });
                b.create().show();
                return true;
            }

            @Override
            public boolean onJsPrompt(WebView view, String url, String message, String defaultValue,
                                      final JsPromptResult result) {
                result.confirm();
                return super.onJsPrompt(view, url, message, message, result);
            }

        });

        webView.loadUrl(url);
        setContentView(webView);
    }
}