• 代码如下:

package cn.medua.loadhtml;

import android.Manifest;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.PixelFormat;
import android.hardware.display.DisplayManager;
import android.hardware.display.VirtualDisplay;
import android.media.Image;
import android.media.ImageReader;
import android.media.projection.MediaProjection;
import android.media.projection.MediaProjectionManager;
import android.os.Build;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import java.io.FileOutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final int PERMISSION_REQ_ID = 22;
    private static final String[] REQUESTED_PERMISSIONS = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };
    private WebView webView;
    private Button butImg;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        if (checkSelfPermission(REQUESTED_PERMISSIONS[0], PERMISSION_REQ_ID) &&
                checkSelfPermission(REQUESTED_PERMISSIONS[1], PERMISSION_REQ_ID)) {
            setHtml();
        }

    }

    //申请sd卡读写权限
    private boolean checkSelfPermission(String permission, int requestCode) {
        if (ContextCompat.checkSelfPermission(this, permission) !=
                PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, REQUESTED_PERMISSIONS, requestCode);
            return false;
        }
        return true;
    }

    @Override
    public void onRequestPermissionsResult(int requestCode,
                                           @NonNull String[] permissions, @NonNull int[] grantResults) {

        if (requestCode == PERMISSION_REQ_ID) {
            if (grantResults[0] != PackageManager.PERMISSION_GRANTED ||
                    grantResults[1] != PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(MainActivity.this, "暂无权限！！！", Toast.LENGTH_SHORT).show();
                return;
            } else {
                setHtml();
            }
        }
    }

    //加载sd卡里的html文件
    private void initView() {
        webView = (WebView) findViewById(R.id.webView);
        WebSettings ws = webView.getSettings();
        ws.setJavaScriptEnabled(true);
        butImg = (Button) findViewById(R.id.butImg);
        butImg.setOnClickListener(this);
    }

    private void setHtml() {
        webView.loadUrl("file://" + "/storage/emulated/0/loadHtml/index.html");
    }

    @SuppressLint("WrongConstant")
    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.butImg:
                createImage(v);
                break;
        }
    }

    //截屏功能实现
    private void createImage(View v) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd_HH-mm-ss", Locale.US);
        String fname = "/sdcard/" + sdf.format(new Date()) + ".png";
        View view = v.getRootView();
        view.setDrawingCacheEnabled(true);
        view.buildDrawingCache();
        Bitmap bitmap = view.getDrawingCache();
        if (bitmap != null) {
            System.out.println("bitmap got!");
            try {
                FileOutputStream out = new FileOutputStream(fname);
                bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }


}