java生成高质量的缩略图

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");
  }
}

标签： isp

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