JAVA高質量縮放圖片

原文鏈接https://www.iteye.com/blog/luoyahu-1312043

親測好用，不用額外jar包不用裝插件。

    package com.test;  
      
    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 {  
      
        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);  
      
            if (iWidth > iHeight) {  
                resizedImage = i.getScaledInstance(newWidth, (newWidth * iHeight)  
                        / iWidth, Image.SCALE_SMOOTH);  
            } else {  
                resizedImage = i.getScaledInstance((newWidth * iWidth) / iHeight,  
                        newWidth, 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:\\11.jpg");  
    //       resize(originalImage, new File("c:\\11-0.jpg"),150, 0.7f);  
    //       resize(originalImage, new File("c:\\11-1.jpg"),150, 1f);  
             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);  
        }  
    }