1. pom依赖

参见文章基于geotools实现geotif切瓦片。

2. 代码展示

package cn.surpass;

import org.geotools.coverage.grid.GridCoverage2D;
import org.geotools.coverage.grid.io.AbstractGridCoverage2DReader;
import org.geotools.coverage.grid.io.AbstractGridFormat;
import org.geotools.coverage.grid.io.GridFormatFinder;
import org.geotools.coverage.processing.Operations;
import org.geotools.factory.GeoTools;
import org.geotools.factory.Hints;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.imageio.ImageIO;
import javax.media.jai.PlanarImage;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @author surpass
 * @version 1.0
 * @date 2021/11/26 10:12
 */
public class ImageUtils {

    private final static Logger LOGGER = LoggerFactory.getLogger(ImageUtils.class);
    private static final Integer LARGE_THUMB_IMG_WIDTH = 512;

    public static void generateThumb(String filePath, String saveDir,ImageFormat imageFormat) {
        LOGGER.info("处理文件路径为{};输出文件夹路径为:{}", filePath, saveDir);
        
        File file = new File(filePath);
        AbstractGridFormat format = GridFormatFinder.findFormat(file);
        Hints hints = GeoTools.getDefaultHints();
        AbstractGridCoverage2DReader reader = format.getReader(file, hints);

        try {
            //获取图像的宽和高的像素
            GridCoverage2D read = reader.read(null);
            RenderedImage sourceImage = read.getRenderableImage(0, 1).createDefaultRendering();
            int rasterXSize = sourceImage.getWidth();
            int rasterYSize = sourceImage.getHeight();

            LOGGER.info("原始影像的width:{};height:{}", rasterXSize, rasterYSize);

            double scale = LARGE_THUMB_IMG_WIDTH / (double) Math.max(rasterXSize, rasterYSize);

            LOGGER.info("=======>SCALE:{}", scale);

			// 核心代码
            Operations ops = new Operations(null);
            RenderedImage image = ops.scale(read, scale, scale, 0, 0).getRenderedImage();


            if (image == null) {
                LOGGER.error("临时图片生成失败");
                return;
            }
            BufferedImage largeThumb = PlanarImage.wrapRenderedImage(image).getAsBufferedImage();

            //保存图像
            String descFileName = file.getName().replaceAll("^(.*\\.).*$", "$1"+ imageFormat.getFormatStr());

            //文件夹
            File saveFolder = new File(saveDir);
            if (!saveFolder.exists()) {
                saveFolder.mkdirs();
            }
            saveImage(largeThumb, new File(saveFolder, descFileName), imageFormat.getFormatStr());
            LOGGER.info("缩略图生成成功");
        } catch (Exception e) {
            LOGGER.error(e.getMessage(), e);
            throw new RuntimeException("缩略图生成失败," + e.getMessage());
        } finally {
            reader.dispose();
        }
    }
    
    private static void saveImage(BufferedImage image, File descFile, String format) throws Exception {
        try (FileOutputStream fos = new FileOutputStream(descFile)) {
            ImageIO.write(image, format, fos);
            fos.flush();
        } catch (IOException e) {
            throw e;
        }
    }

    public enum ImageFormat{
        IMAGE_FORMAT_PNG("png"),
        IMAGE_FORMAT_WEBP("webp"),
        IMAGE_FORMAT_JPG("jpg");
        
        private String formatStr;

        public String getFormatStr() {
            return formatStr;
        }
        public void setFormatStr(String formatStr) {
            this.formatStr = formatStr;
        }
        private ImageFormat(String formatStr){
            this.formatStr = formatStr;
        }
    }
}