java生成高质量的缩略图详解编程语言

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，需要提前进行裁剪 
      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"); 
  } 
}