java高质量缩放图片

可按照比例缩放，也可以指定宽高

 import com.sun.image.codec.jpeg.JPEGImageEncoder;
 import com.sun.image.codec.jpeg.JPEGCodec;
 import com.sun.image.codec.jpeg.JPEGEncodeParam;
 import javax.swing.*;
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.awt.*;
 import java.awt.image.BufferedImage;
 import java.awt.image.Kernel;
 import java.awt.image.ConvolveOp;

 public class ImageUtil {
      /**
      *
      * @param originalFile  原文件
      * @param resizedFile  压缩目标文件
      * @param newWidth  压缩后的图片宽度
      * @param quality  压缩质量（0到1之间，越高质量越好）
      * @throws IOException
      */

     public static void resize(File originalFile, File resizedFile,
             int newWidth, float quality) throws IOException {

         if (quality > 1) {
             throw new IllegalArgumentException(
                     "Quality has to be between 0 and 1");
         }

         ImageIcon ii = new ImageIcon(originalFile.getCanonicalPath());
         Image i = ii.getImage();
         Image resizedImage = null;

         int iWidth = i.getWidth(null);
         int iHeight = i.getHeight(null);
                 //比例缩放
         if (iWidth > iHeight) {
             resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight)
                     / iWidth, Image.SCALE_SMOOTH);
         } else {
             resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight,
                     newWidth, Image.SCALE_SMOOTH);
         }
                 //指定宽高
                 //resizedImage = i.getScaledInstance(560,315, Image.SCALE_SMOOTH);
         // This code ensures that all the pixels in the image are loaded.
         Image temp = new ImageIcon(resizedImage).getImage();

         // Create the buffered image.
         BufferedImage bufferedImage = new BufferedImage(temp.getWidth(null),
                 temp.getHeight(null), BufferedImage.TYPE_INT_RGB);

         // Copy image to buffered image.
         Graphics g = bufferedImage.createGraphics();

         // Clear background and paint the image.
         g.setColor(Color.white);
         g.fillRect(0, 0, temp.getWidth(null), temp.getHeight(null));
         g.drawImage(temp, 0, 0, null);
         g.dispose();

         // Soften.
         float softenFactor = 0.05f;
         float[] softenArray = { 0, softenFactor, 0, softenFactor,
                 1 - (softenFactor * 4), softenFactor, 0, softenFactor, 0 };
         Kernel kernel = new Kernel(3, 3, softenArray);
         ConvolveOp cOp = new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
         bufferedImage = cOp.filter(bufferedImage, null);

         // Write the jpeg to a file.
         FileOutputStream out = new FileOutputStream(resizedFile);

         // Encodes image as a JPEG data stream
         JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);

         JPEGEncodeParam param = encoder
                 .getDefaultJPEGEncodeParam(bufferedImage);

         param.setQuality(quality, true);

         encoder.setJPEGEncodeParam(param);
         encoder.encode(bufferedImage);
     } // Example usage

     public static void main(String[] args) throws IOException {
          File originalImage = new File("C:\1207.gif");
          resize(originalImage, new File("c:\1207-0.jpg"),150, 0.7f);
          resize(originalImage, new File("c:\1207-1.jpg"),150, 1f);
     }
 }

参考博文：https://www.wanpishe.top/detail?blogId=f80863fd-f8d5-4da0-8f4e-6537ba13bd91