ImageTool

import java.awt.Color;import java.awt.Graphics2D;import java.awt.Image;import java.awt.image.BufferedImage;import java.io.File;import java.io.IOException;import javax.imageio.ImageIO;public class ImageTool {public static final int WIDTH = 240;public static final int HEIGTH = 240;public static void getPreviewImage(File source, File destImage, String format){try {BufferedImage bufferedImage = ImageIO.read(source);BufferedImage image = new BufferedImage(WIDTH, HEIGTH, BufferedImage.TYPE_INT_RGB);//创建缩放后的画布  TYPE_INT_RGB是具有合成整数像素的 8 位 RGB 颜色分量int x = bufferedImage.getWidth();int y = bufferedImage.getHeight();int x1 = WIDTH;int y1 = HEIGTH;if(WIDTH*y<HEIGTH*x){  //高度不够y1 = WIDTH*y/x;}if(WIDTH*y<HEIGTH*x){  //宽度不够x1 = HEIGTH*x/y;}Graphics2D graphics2d = image.createGraphics();graphics2d.setColor(new Color(255,255,255));graphics2d.fillRect(0, 0, WIDTH, HEIGTH);Image image2 = bufferedImage.getScaledInstance(x1, y1, bufferedImage.SCALE_SMOOTH);graphics2d.drawImage(image2, (WIDTH-x1)/2, (HEIGTH-y1)/2, null);ImageIO.write(image, format, destImage);} catch (Exception e) {e.printStackTrace();}}public static void main(String[] args) {getPreviewImage(new File("e:/re.png"),new File("e:/aa.jpg"),"jpg");}}