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Java サムネイルイメージの作成


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Java サムネイルイメージの作成

[Java][コード片]

import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.imageio.ImageIO;

/**
 * サムネイルJpegを生成する
 * @author Yagi Hiroto
 */
public class ThumnailImageCreater {
  /**
   * InputSteramに関連付けられたイメージ
   * 
   * @param in
   * @param out
   * @param formatName
   * @param rate
   * @throws IOException
   * @throws ImageServiceException
   */
  public void writeThumbNailImage(InputStream in, 
          OutputStream out,
          String formatName, 
          double rate) throws Exception {

    BufferedImage image = ImageIO.read(in);
    writeThumbNailImage(out, image, formatName, rate);
  }

  /**
   * @param in
   * @param out
   * @param rate
   * @throws IOException
   * @throws ImageServiceException
   */
  public void writeThumbNailImage(InputStream in, 
          OutputStream out,
          double rate) throws Exception {

    writeThumbNailImage(in, out, "jpeg", rate);
  }

  /**
   * @param in
   * @param out
   * @param width
   * @param height
   * @throws IOException
   * @throws ImageServiceException
   */
  public void writeThumbNailImage(InputStream in, 
          OutputStream out,
          int width,
          int height) throws Exception {
  
    writeThumbNailImage(in, out, "jpeg", width, height);
  }

  /**
   * @param in
   * @param out
   * @param formatName
   * @param width
   * @param height
   * @throws IOException
   * @throws ImageServiceException
   */
  public void writeThumbNailImage(InputStream in, 
          OutputStream out,
          String formatName, 
          int width, 
          int height) throws Exception {
  
    BufferedImage image = ImageIO.read(in);
    double rate = calcRatio(width, height, image);
    writeThumbNailImage(out, image, formatName, rate);
  }

  /**
   * 指定されたサイズに収まる縮小率を算出する
   * 
   * @param width
   * @param height
   * @param image
   * @return
   */
  private double calcRatio(int width, int height, BufferedImage image) {
    double wRate = (double) width  / (double) image.getWidth();
    double hRate = (double) height / (double) image.getHeight();
    return (wRate < hRate) ? wRate : hRate;
  }

  /**
   * @param out
   * @param image
   * @param formatName
   * @param rate
   * @throws IOException
   * @throws ImageServiceException
   */
  public void writeThumbNailImage( OutputStream out, 
                 BufferedImage image,
                 String formatName, 
                 double rate) throws Exception {
  
    BufferedImage shrinkImage = new BufferedImage(
          (int) (image.getWidth() * rate),
          (int) (image.getHeight() * rate), 
          image.getType());
  
    AffineTransformOp atOp = new AffineTransformOp(
          AffineTransform.getScaleInstance(rate, rate), null);
  
    atOp.filter(image, shrinkImage);
    boolean ret = ImageIO.write(shrinkImage, formatName, out);
    if (!ret) {
      throw new Exception("writer not found.");
    }
  }

  /**
   * @param args
   */
  public static void main(String[] args) {

    if (args.length <= 3) {
      printUsage();
    }

    FileInputStream in = null;
    FileOutputStream out = null;
    try {
      String srcFilename = args[0].trim();
      String dstFilename = args[1].trim();

      if (srcFilename.equals(dstFilename)) {
        System.out.println("ERROR : 変換前のファイル名と、変換後のファイル名が同じです");
      }

      int width = 0;
      int height = 0;
      double ratio = 0.0;

      for (int i = 0; i < args.length; i++) {
        if ("-w".equalsIgnoreCase(args[i].trim())) {
          width = Integer.parseInt(args[i + 1]);
        } else if ("-h".equalsIgnoreCase(args[i].trim())) {
          height = Integer.parseInt(args[i + 1]);
        } else if ("-r".equalsIgnoreCase(args[i].trim())) {
          ratio = Double.parseDouble(args[i + 1]);
        }
      } 
      in  = new FileInputStream(new File(srcFilename));
      out = new FileOutputStream(new File(dstFilename));

      ThumnailImageCreater me = new ThumnailImageCreater();

      if (width > 0 || height > 0) {
        me.writeThumbNailImage(in, out, width, height);
      } else if (ratio > 0) {
        me.writeThumbNailImage(in, out, ratio);
      } else {
        System.out.println("ERROR : サイズが指定されていません");
      }
      System.out.println("完了しました");

    } catch (Exception e) {
      e.printStackTrace();
      printUsage();
    } finally {
      try {
        if (in != null)
          in.close();
        if (out != null)
          out.close();
      } catch (Exception e) {
      }
    }
  }

  /**
   * 
   */
  private static void printUsage() {
    String usage = "usage ThumNailImage " + "originalfilename "
       + "shrinkfilename " + "[-w width]" + "[-h height]"
       + "[-r ratio]";
    System.out.println(usage);
    System.exit(0);
  }
}



YAGI Hiroto (piroto@a-net.email.ne.jp)
twitter http://twitter.com/pppiroto

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