ImagePreview

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package zthh.manager.commons;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import sun.misc.BASE64Encoder;
import javax.imageio.*;

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.io.output.DeferredFileOutputStream;
import org.apache.log4j.Logger;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class ImagePreview {
private final static Logger LOGGER = Logger.getLogger(ImagePreview.class);
public ImagePreview(){

}

@SuppressWarnings("unchecked")
public String ProcessRequest(HttpServletRequest request) throws ServletException, IOException{
  BASE64Encoder encoder = new BASE64Encoder();

  byte[] bs = null;
  long filesize = 0;

  DiskFileItemFactory factory = new DiskFileItemFactory();

  int width = 0;
  int height = 0;

  InputStream inputStream = null;
  ByteArrayOutputStream op = null;
  DeferredFileOutputStream dfo = null;

  try{
   factory.setSizeThreshold(4096);// ��û��,��ֵ��fileinputstream��bytearrayinputstream
   //factory.setRepository(new File("d://temp"));//��ʱ��Ŀ¼,Ĭ��new File(System.getProperty("java.io.tmpdir"))
   ServletFileUpload sfileUpLoad = new ServletFileUpload(factory);
   sfileUpLoad.setSizeMax(10*1024*1024);//10M
   List items = sfileUpLoad.parseRequest(request);
   Iterator it = items.iterator();
   //��ʱֻ��ǵ��ļ�
   while(it.hasNext()){
    FileItem fileItem = (FileItem)it.next();
    if(!fileItem.isFormField()){
     inputStream = fileItem.getInputStream();
     filesize = fileItem.getSize();
     bs = new byte[(int)filesize];

    }else{
     if (fileItem.getFieldName().equals("width")) {
      dfo = (DeferredFileOutputStream) fileItem.getOutputStream();
      width = Integer.parseInt(new String(dfo.getData()));
     }
     if (fileItem.getFieldName().equals("height")) {
      dfo = (DeferredFileOutputStream) fileItem.getOutputStream();
      height = Integer.parseInt(new String(dfo.getData()));
     }
    }
   }

   op = ResizeImg(inputStream, width, height);

   bs = op.toByteArray();

   String imgpath = "data:image/jpeg;base64," ;
   String img = encoder.encode(bs);

   imgpath += img;

   return imgpath;
  }catch (FileUploadException e) {
   e.printStackTrace();
   LOGGER.error(e);
  } catch (IOException e) {
   e.printStackTrace();
   LOGGER.error(e);
  }finally{
   if(dfo != null){
    dfo.close();
   }
   if(inputStream != null){
    inputStream.close();
   }
   if(op!= null){
    op.close();
   }
  }

  //blankimage
  return "data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==";

}

//ֻ��jpg��
@SuppressWarnings("static-access")
public ByteArrayOutputStream ResizeImg(InputStream inputStream,int maxWidth,int maxHeight) throws IOException{

  BufferedImage bufferimage = ImageIO.read(inputStream);
  int curWidth = bufferimage.getWidth();
  int curHeight = bufferimage.getHeight();

//  double desiredRatio = Math.min((double)(maxWidth)/(double)curWidth,(double)maxHeight/(double)curHeight);
//  curWidth = (int) (curWidth*desiredRatio);
//  curHeight = (int)(curHeight*desiredRatio);
  double ratio = 0;
  Image itemp = bufferimage.getScaledInstance(maxWidth, maxHeight, bufferimage.SCALE_SMOOTH);
        // ��
        if ((bufferimage.getHeight() > maxHeight) || (bufferimage.getWidth() > maxWidth)) {
            if (bufferimage.getHeight() > bufferimage.getWidth()) {
                ratio = (new Integer(maxHeight)).doubleValue() / bufferimage.getHeight();
            } else {
                ratio = (new Integer(maxWidth)).doubleValue() / bufferimage.getWidth();
            }
            AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio), null);
            itemp = op.filter(bufferimage, null);
        }


  BufferedImage bufftmp = new BufferedImage(curWidth,curHeight,BufferedImage.TYPE_INT_RGB);
  Graphics2D g2D = bufftmp.createGraphics();

  g2D.setColor(Color.white);
  g2D.fillRect(0, 0, curWidth, curHeight);
//  g2D.drawImage(bufferimage, null, 0, 0);

  if (maxWidth == itemp.getWidth(null))
   g2D.drawImage(itemp, 0, (maxHeight - itemp.getHeight(null)) / 2, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);
        else
        g2D.drawImage(itemp, (maxWidth - itemp.getWidth(null)) / 2, 0, itemp.getWidth(null), itemp.getHeight(null), Color.white, null);
  g2D.dispose();
//        itemp = bufftmp;

  ByteArrayOutputStream op = new ByteArrayOutputStream();

  JPEGImageEncoder imageEncoder = JPEGCodec.createJPEGEncoder(op);

  imageEncoder.encode((BufferedImage)itemp);

  return op;
}

}