1、 当我使用 android webview 打开本地 html 时，页面的 layui 的路由 使用 ajax 读取html、less文件采用了发请求的方式，所以出现了跨域问题。

2、h5 type=file  选择文件打不开

解决上面问题，webView 代码示例：

public class MainActivity extends AppCompatActivity {
    public WebView webView;
     
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        webView = (WebView) findViewById(R.id.webView1);

        setUpView("file:///android_asset/www/login.html");
    }


@SuppressLint("SetJavaScriptEnabled")
    public void setUpView(String url) {
        //加载需要显示的网页
//        webView = new WebView(this); 不在xml中创建webview 也可以在这new
//        setContentView(webView);
        webView.loadUrl(url);
        WebSettings webSettings = webView.getSettings();
        webSettings.setJavaScriptEnabled(true);  //设置WebView属性,运行执行js脚本
//        webSettings.setSafeBrowsingEnabled(false);
        webSettings.setAllowContentAccess(true);
        webSettings.setAllowFileAccess(true);
        webSettings.setDomStorageEnabled(true);
        webSettings.setUseWideViewPort(true);//设定支持viewport
        webSettings.setLoadWithOverviewMode(true);//自适应屏幕
        webSettings.setBuiltInZoomControls(true);
        webSettings.setDisplayZoomControls(false);
        webSettings.setJavaScriptCanOpenWindowsAutomatically(true);
        webSettings.setSupportZoom(true);//设定支持缩放
        webSettings.setCacheMode(WebSettings.LOAD_NO_CACHE);//不读取缓存
//        webSettings.setMixedContentMode(WebSettings.MIXED_CONTENT_ALWAYS_ALLOW);//api 16 不支持
        webView.setBackgroundColor(ContextCompat.getColor(this,android.R.color.transparent));
//        webView.setBackgroundResource(R.color.black);
        webView.setWebViewClient(webClient);  //设置Web视图

        try {//本地HTML里面有跨域的请求 原生webview需要设置之后才能实现跨域请求（less、layui路由）
            if (Build.VERSION.SDK_INT >= 16) {
                Class<?> clazz = webView.getSettings().getClass();
                Method method = clazz.getMethod(
                        "setAllowUniversalAccessFromFileURLs", boolean.class);
                if (method != null) {
                    method.invoke(webView.getSettings(), true);
                }
            }
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }



        // 解决webView 不支持h5 type=file 选择文件弹框
        webView.setWebChromeClient(new WebChromeClient() {
            // For 3.0+ Devices (Start)
            // onActivityResult attached before constructor
            protected void openFileChooser(ValueCallback uploadMsg, String acceptType)
            {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                startActivityForResult(Intent.createChooser(i, "File Browser"), FILECHOOSER_RESULTCODE);
            }


            // For Lollipop 5.0+ Devices
            @TargetApi(Build.VERSION_CODES.LOLLIPOP)
            public boolean onShowFileChooser(WebView mWebView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams)
            {
                if (uploadMessage != null) {
                    uploadMessage.onReceiveValue(null);
                    uploadMessage = null;
                }

                uploadMessage = filePathCallback;

                Intent intent = fileChooserParams.createIntent();
                try
                {
                    startActivityForResult(intent, REQUEST_SELECT_FILE);
                } catch (ActivityNotFoundException e)
                {
                    uploadMessage = null;
                    Toast.makeText(getBaseContext(), "Cannot Open File Chooser", Toast.LENGTH_LONG).show();
                    return false;
                }
                return true;
            }

            //For Android 4.1 only
            protected void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture)
            {
                mUploadMessage = uploadMsg;
                Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
                intent.addCategory(Intent.CATEGORY_OPENABLE);
                intent.setType("image/*");
                startActivityForResult(Intent.createChooser(intent, "File Browser"), FILECHOOSER_RESULTCODE);
            }

            protected void openFileChooser(ValueCallback<Uri> uploadMsg)
            {
                mUploadMessage = uploadMsg;
                Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                i.addCategory(Intent.CATEGORY_OPENABLE);
                i.setType("image/*");
                startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE);
            }

        });
    }


    WebViewClient webClient = new WebViewClient() {
        //设置打开网页时，不调用系统浏览器进行打开，而是在本WebView中直接显示。
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url) {
            view.loadUrl(url);
//            Toast.makeText(MainActivity.this, "开始加载", Toast.LENGTH_SHORT).show();
            return true;
        }

        @Override
        public void onPageStarted(WebView view, String url, Bitmap favicon) {
            super.onPageStarted(view, url, favicon);
            //加载开始的操作
        }

        @Override
        public void onPageFinished(WebView view, String url) {
            super.onPageFinished(view, url);
            //加载结束的操作
        }

        @Override
        public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
            super.onReceivedError(view, request, error);
            //加载页面的服务器出现错误时（如404）调用
            System.out.println("资源加载和页面打开错误时都会进入");
            //回调失败的相关操作
        }

        @Override
        public void onReceivedError(WebView view, int errorCode,
                                    String description, String failingUrl) {

        }
    };




}

 添加访问网络权限（AndroidManifest.xml）

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

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <WebView
        android:id="@+id/webView1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:layout_editor_absoluteX="1dp"
        tools:layout_editor_absoluteY="1dp"
        tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>