<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <View
        android:layout_width="match_parent"
        android:layout_height="200dp"/>

    <ImageView
        android:id="@+id/bgPhoto"
        android:layout_width="340dp"
        android:layout_height="254dp"
        android:layout_gravity="center"
        android:background="@drawable/photo"/>

    <Button
        android:id="@+id/btn"
        android:layout_width="100dp"
        android:layout_height="60dp"
        android:text="下载"
        android:layout_marginTop="20dp"
        android:layout_gravity="center"/>

</LinearLayout>

package top.gaojc;

import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import top.gaojc.util.DownloadPhotoUtil;
import top.gaojc.util.ImageUtil;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    private ImageView bgPhoto;//图片控件
    private Button btn;//下载按钮
    private Context mContext = MainActivity.this;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bgPhoto = findViewById(R.id.bgPhoto);
        btn = findViewById(R.id.btn);

        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(mContext, "下载至手机", Toast.LENGTH_SHORT).show();
                // 调用相关工具类
                DownloadPhotoUtil.requestPermission(MainActivity.this, ImageUtil.createBitmapFromView(bgPhoto));
            }
        });
        
    }
    
}

package top.gaojc.util;

import android.Manifest;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Build;
import android.os.Environment;
import android.provider.MediaStore;
import android.text.format.DateUtils;
import android.widget.Toast;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.text.SimpleDateFormat;
import java.util.Date;

import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

public class DownloadPhotoUtil {

    private static Activity mContext;
    private static final int REQUEST_CODE_SAVE_IMG = 0;

    /**
     * 请求读取sd卡的权限
     */
    public static void requestPermission(Activity context, Bitmap bitmap) {
        mContext = context;
        /**
         * 添加读写权限
         *      READ_EXTERNAL_STORAGE：读外部存储的权限
         *      WRITE_EXTERNAL_STORAGE：写外部存储的权限
         */
        String[] mPermissionList = new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE};
        // 判断有无读写权限
        if (hasPermissions(mContext, mPermissionList)) {
            // 已同意 去保存
            saveImage(context, bitmap);
        } else {
            // 未同意 申请权限
            ActivityCompat.requestPermissions(context, mPermissionList, REQUEST_CODE_SAVE_IMG);
        }
    }

    // 是否有对应权限
    public static boolean hasPermissions(Context context, String... perms) {
        // 判断sdk版本
        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) {
            return true;
        }
        for (String perm : perms) {
            boolean hasPerm = (ContextCompat.checkSelfPermission(context, perm) ==
                    PackageManager.PERMISSION_GRANTED);
            if (!hasPerm) {
                return false;
            }
        }
        return true;
    }

    // 保存图片
    public static void saveImage(Context context, Bitmap bitmap) {
        if (bitmap == null) {
            return;
        }
        boolean isSaveSuccess;
        if (Build.VERSION.SDK_INT < 29) {
            isSaveSuccess = saveImageToGallery(context, bitmap);
        } else {
            isSaveSuccess = saveImageToGallery1(context, bitmap);
        }
        if (isSaveSuccess) {
            Toast.makeText(mContext, "保存图片成功", Toast.LENGTH_SHORT).show();
        } else {
            Toast.makeText(mContext, "保存图片失败，请稍后重试", Toast.LENGTH_SHORT).show();
        }
    }

    /**
     * android 10 以下版本
     */
    public static boolean saveImageToGallery(Context context, Bitmap image) {
        // 首先保存图片
        String storePath = Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "dearxy";

        File appDir = new File(storePath);
        if (!appDir.exists()) {
            appDir.mkdir();
        }
        String fileName = System.currentTimeMillis() + ".jpg";
        File file = new File(appDir, fileName);
        try {
            FileOutputStream fos = new FileOutputStream(file);
            // 通过io流的方式来压缩保存图片
            boolean isSuccess = image.compress(Bitmap.CompressFormat.JPEG, 60, fos);
            fos.flush();
            fos.close();

            // 保存图片后发送广播通知更新数据库
            Uri uri = Uri.fromFile(file);
            mContext.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, uri));
            if (isSuccess) {
                return true;
            } else {
                return false;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * android 10 以上版本
     */
    public static boolean saveImageToGallery1(Context context, Bitmap image) {
        Long mImageTime = System.currentTimeMillis();
        String imageDate = new SimpleDateFormat("yyyyMMdd-HHmmss").format(new Date(mImageTime));
        String SCREENSHOT_FILE_NAME_TEMPLATE = "winetalk_%s.png";//图片名称，以"winetalk"+时间戳命名
        String mImageFileName = String.format(SCREENSHOT_FILE_NAME_TEMPLATE, imageDate);

        final ContentValues values = new ContentValues();
        values.put(MediaStore.MediaColumns.RELATIVE_PATH, Environment.DIRECTORY_PICTURES
                + File.separator + "winetalk"); //Environment.DIRECTORY_SCREENSHOTS:截图,图库中显示的文件夹名。"dh"
        values.put(MediaStore.MediaColumns.DISPLAY_NAME, mImageFileName);
        values.put(MediaStore.MediaColumns.MIME_TYPE, "image/png");
        values.put(MediaStore.MediaColumns.DATE_ADDED, mImageTime / 1000);
        values.put(MediaStore.MediaColumns.DATE_MODIFIED, mImageTime / 1000);
        values.put(MediaStore.MediaColumns.DATE_EXPIRES, (mImageTime + DateUtils.DAY_IN_MILLIS) / 1000);
        values.put(MediaStore.MediaColumns.IS_PENDING, 1);

        ContentResolver resolver = context.getContentResolver();
        final Uri uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
        try {
            // First, write the actual data for our screenshot
            try (OutputStream out = resolver.openOutputStream(uri)) {
                if (!image.compress(Bitmap.CompressFormat.PNG, 100, out)) {
                    return false;
                }
            }
            // Everything went well above, publish it!
            values.clear();
            values.put(MediaStore.MediaColumns.IS_PENDING, 0);
            values.putNull(MediaStore.MediaColumns.DATE_EXPIRES);
            resolver.update(uri, values, null, null);
        } catch (IOException e) {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R){
                resolver.delete(uri, null);
            }
            return false;
        }
        return true;
    }
}

package top.gaojc.util;

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.view.View;
import android.widget.ImageView;

public class ImageUtil {

    // view转bitmap
    public static Bitmap createBitmapFromView(View view) {
        //是ImageView直接获取
        if (view instanceof ImageView) {
            Drawable drawable = ((ImageView) view).getDrawable();
            if (drawable instanceof BitmapDrawable) {
                return ((BitmapDrawable) drawable).getBitmap();
            }
        }
        view.clearFocus();
        Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
        if (bitmap != null) {
            Canvas canvas = new Canvas(bitmap);
            view.draw(canvas);
            canvas.setBitmap(null);
        }
        return bitmap;
    }

}