Java图像合并与保存：深入理解ImageIO.write与图像类型选择

import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class ImageMerger {
    public static void main(String[] args) {
        String imagePath = "../../Desktop/temp/"; // 假设图片在此路径下
        File leftFile = new File(imagePath + "006.jpg");
        File rightFile = new File(imagePath + "007.jpg");

        try {
            BufferedImage leftImage = ImageIO.read(leftFile);
            BufferedImage rightImage = ImageIO.read(rightFile);

            if (leftImage == null || rightImage == null) {
                System.err.println("无法读取一个或多个图像文件，请检查路径或文件格式。");
                return;
            }

            // 调用合并方法
            BufferedImage mergedImage = mergeImagesHorizontally(leftImage, rightImage);

            // 保存合并后的图像
            File outputFile = new File(imagePath + "merged_image.jpg");
            boolean success = ImageIO.write(mergedImage, "jpg", outputFile);
            System.out.println("图像保存成功: " + success + "，路径: " + outputFile.getAbsolutePath());

        } catch (IOException e) {
            e.printStackTrace();
            System.err.println("图像处理过程中发生IO错误。");
        }
    }

    /**
     * 水平合并两张图片，左图在左，右图在右。
     *
     * @param leftImage 左侧图片
     * @param rightImage 右侧图片
     * @return 合并后的BufferedImage
     */
    public static BufferedImage mergeImagesHorizontally(BufferedImage leftImage, BufferedImage rightImage) {
        // 计算合并后图像的宽度和高度
        int totalWidth = leftImage.getWidth() + rightImage.getWidth();
        int maxHeight = Math.max(leftImage.getHeight(), rightImage.getHeight());

        // 创建新的BufferedImage作为画布。关键在于选择合适的图像类型。
        // 对于JPEG格式，通常选择TYPE_INT_RGB，因为JPEG不支持透明度。
        BufferedImage mergedImage = new BufferedImage(totalWidth, maxHeight, BufferedImage.TYPE_INT_RGB);

        // 获取Graphics2D对象，用于绘制图像
        Graphics2D g2d = mergedImage.createGraphics();

        // 将左侧图像绘制到新图像的左侧 (0, 0) 位置
        g2d.drawImage(leftImage, 0, 0, null);

        // 将右侧图像绘制到新图像的右侧，紧接在左侧图像之后
        g2d.drawImage(rightImage, leftImage.getWidth(), 0, null);

        // 释放Graphics2D资源，避免内存泄漏
        g2d.dispose();

        return mergedImage;
    }
}

// 更改前 (可能导致JPG保存失败):
// BufferedImage mergedImage = new BufferedImage(totalWidth, maxHeight, BufferedImage.TYPE_INT_ARGB);

// 更改后 (适用于JPG保存):
BufferedImage mergedImage = new BufferedImage(totalWidth, maxHeight, BufferedImage.TYPE_INT_RGB);