java生成高質量的縮略圖

package com.hxy.secrets.util;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;
import javax.swing.ImageIcon;
public class ImageUtils {
  public static byte[] resize(BufferedImage srcBufferedImage, int targetWidth)
      throws IOException {
    return resize(srcBufferedImage, targetWidth, 1f, false);
  }
public static byte[] resize(BufferedImage srcBufferedImage,
      int targetWidth, boolean square) throws IOException {
    return resize(srcBufferedImage, targetWidth, square);
  }
public static byte[] resize(BufferedImage srcBufferedImage,
      int targetWidth, float quality, boolean square) throws IOException {
    if (quality > 1) {
      throw new IllegalArgumentException(
          "Quality has to be between 0 and 1");
    }
    if (square) {
      // 正方形，需要提前進行裁剪
      int width = srcBufferedImage.getWidth();
      int height = srcBufferedImage.getHeight();
      if (width > height) {
        int x = (width - height) / 2;
        srcBufferedImage = srcBufferedImage.getSubimage(x, 0, height,
            height);
      } else if (width < height) {
        int y = (height - width) / 2;
        srcBufferedImage = srcBufferedImage.getSubimage(0, y, width,
            width);
      }
    }

Image resizedImage = null;
int iWidth = srcBufferedImage.getWidth();
int iHeight = srcBufferedImage.getHeight();

if (iWidth > iHeight) {
  resizedImage = srcBufferedImage.getScaledInstance(targetWidth,
      (targetWidth * iHeight) / iWidth, Image.SCALE_SMOOTH);
} else {
  resizedImage = srcBufferedImage.getScaledInstance(
      (targetWidth * iWidth) / iHeight, targetWidth,
      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.

// Encodes image as a JPEG data stream
// JPEGImageEncoder encoder = JPEGCodeca
// .createJPEGEncoder(byteArrayOutputStream);
//
// JPEGEncodeParam param = encoder
// .getDefaultJPEGEncodeParam(bufferedImage);
//
// param.setQuality(quality, true);
//
// encoder.setJPEGEncodeParam(param);
// encoder.encode(bufferedImage);

ImageWriter writer = ImageIO.getImageWritersByFormatName("jpeg").next();
ImageWriteParam param = writer.getDefaultWriteParam();
param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
param.setCompressionQuality(1.0F); // Highest quality
// Write the JPEG to our ByteArray stream
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ImageOutputStream imageOutputStream = ImageIO
    .createImageOutputStream(byteArrayOutputStream);
writer.setOutput(imageOutputStream);
writer.write(null, new IIOImage(bufferedImage, null, null), param);
return byteArrayOutputStream.toByteArray();

}
// Example usage
  public static void main(String[] args) throws IOException {

File originalImage = new File("E:/111.jpg");
byte[] bytes = resize(ImageIO.read(originalImage), 100, 1f, true);
FileOutputStream out = new FileOutputStream(new File("E:/66.jpg"));
out.write(bytes);
out.close();
System.out.println("Ok");

}
}</pre>