javax.imageio图像处理教程：读取写入转换图像完整指南

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

public class ImageReadExample {
    public static void main(String[] args) {
        try {
            // 读取图像文件
            File file = new File("input.jpg");
            BufferedImage image = ImageIO.read(file);
            
            // 获取图像信息
            int width = image.getWidth();
            int height = image.getHeight();
            int type = image.getType();
            
            System.out.println("宽度: " + width);
            System.out.println("高度: " + height);
            System.out.println("类型: " + type);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

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

public class ImageConvertExample {
    public static void main(String[] args) {
        try {
            // 读取 JPEG 图像
            BufferedImage image = ImageIO.read(new File("input.jpg"));
            
            // 转换为 PNG 格式保存
            ImageIO.write(image, "png", new File("output.png"));
            System.out.println("转换完成！");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import javax.imageio.ImageIO;

public class SupportedFormats {
    public static void main(String[] args) {
        // 获取支持的读取格式
        String[] readers = ImageIO.getReaderFormatNames();
        System.out.println("支持的读取格式:");
        for (String format : readers) {
            System.out.println(" - " + format);
        }

        // 获取支持的写入格式
        String[] writers = ImageIO.getWriterFormatNames();
        System.out.println("支持的写入格式:");
        for (String format : writers) {
            System.out.println(" - " + format);
        }
    }
}

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

public class ResizeImage {
    public static void main(String[] args) {
        try {
            BufferedImage originalImage = ImageIO.read(new File("input.jpg"));
            
            // 目标尺寸
            int newWidth = 300;
            int newHeight = 200;
            
            // 创建缩放后的图像
            BufferedImage resizedImage = new BufferedImage(
                newWidth, newHeight, BufferedImage.TYPE_INT_RGB
            );
            Graphics2D g = resizedImage.createGraphics();
            g.drawImage(originalImage, 0, 0, newWidth, newHeight, null);
            g.dispose();
            
            // 保存调整后的图像
            ImageIO.write(resizedImage, "jpg", new File("resized.jpg"));
            System.out.println("图像缩放完成！");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}