png 图片的缩放

图片缩放的例子

import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;

import junit.framework.TestCase;

public class NarrowImg extends TestCase {


/**
 * @param sourceImage 要缩放的源文件路径
 * @param targetImage 缩放后目标文件前缀
 * @param type        缩放后目标文件后缀
 */
	public boolean CreateThumbnail(String sourceImage,String targetImage,String type) throws Exception {
		double Ratio_width = 0.0; // 宽度的缩放比例
		double Ratio_height = 0.0; // 高度的缩放比例
		File F = new File(sourceImage);
		if (!F.isFile())
		throw new Exception(F+ " is not image file error in CreateThumbnail!");
		File targetFile = new File(targetImage+"."+type);

		BufferedImage Bi = ImageIO.read(F);
		
		// 假设图片宽 高 最大为120 120
		Image Itemp = Bi.getScaledInstance(120, 120, BufferedImage.SCALE_SMOOTH);
		Ratio_width = 120.0 / Bi.getHeight();
		Ratio_height = 120.0 / Bi.getWidth();

		AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(Ratio_width, Ratio_height), null);
		Itemp = op.filter(Bi, null);

		try {
			ImageIO.write((BufferedImage) Itemp, type, targetFile);
		} catch (Exception ex) {
			throw new Exception(" ImageIo.write error in CreatThum.: "+ ex.getMessage());
		}
		
		return true;
	}
}

原图片

缩放后