java 对 上传图片剪切

 

java 对 上传图片剪切

一般上传图片分三步：

第一步：将原始图片上传到服务器端保存，不妨命名为src.jpg

第二步：在浏览器端将src.jpg显示出来，然后使用jQuery,对其进行“客户端剪切”。

              所谓客户端剪切就是根据用户在界面中对原始图片放大，移动，剪切时，获得一些参数。

             具体需要六个参数（srcWidth, srcHeight,  rect.x,  rect.y  , rect.width, rect.height）参数。

             其中，srcWidth 和srcHeight表明原始图片在客户端放大后的宽和高

                       rect.x和rect.y表明剪切部分相对(srcWidth, srcHeight)的起始坐标

                       rect.width和rect.height表示需要剪切的图片的大小。

第三步：获取第二步得到的参数，对内存中原始图片先进行预处理（按照srcWidth和srcHeight进行缩放）、剪切。

             然后对预处理后的内存图像剪切，打印出来。

第一步实现比较简单，第二步需要学习jQuery，网上例子很多。我们重点讨论第三步， java切图。

//1.main函数

package syj.main;

import java.awt.Rectangle;
import java.io.File;
import java.io.IOException;

import syj.util.ImageHepler;

public class Test {
public static void main(String[] args) throws IOException {
  String picPath = "img/src.jpg";
  String destPath = "img/result.jpg";
  Rectangle rect = new Rectangle(0, 0, 2000, 1200);
  ImageHepler.cut(picPath, destPath, 1440, 900, rect);
}
}

//2.关键图像操作函数

package syj.util;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.io.PrintStream;
import javax.imageio.ImageIO;

public class ImageHepler {

/**
  * @Description: 将srcImageFile裁剪后生成destImageFile
  * @param srcImageFile  原始图
  * @param destImageFile  目标图
  * @param width          原始图预处理后width
  * @param height         原始图预处理后height
  * @param rect           目标图输出的格式(rect.x, rect.y, rect.width, rect.height)
  * @throws IOException
  * @author Sun Yanjun
  */
public static void cut(String srcImageFile, String destImageFile, int width, int height, Rectangle rect) throws IOException {
  Image image = ImageIO.read(new File(srcImageFile));
  BufferedImage bImage = makeThumbnail(image, width, height);

  //把原始图片输出
  ImageIO.write(bImage, "jpg",new File("img/src2.jpg"));
 
  saveSubImage(bImage, rect, new File(destImageFile));
}

/**
  * @Description: 将srcImageFile裁剪后生成destImageFile
  * @param srcImageFile  原始图
  * @param destImageFile  目标图
  * @param width          原始图预处理后width
  * @param height         原始图预处理后height
  * @param rect           目标图输出的格式(rect.x, rect.y, rect.width, rect.height)
  * @throws IOException
  * @author Sun Yanjun
  */
public static void cut(File srcImageFile, File destImageFile, int width, int height, Rectangle rect) throws IOException {
  Image image = ImageIO.read(srcImageFile);
  BufferedImage bImage = makeThumbnail(image, width, height);

 
  saveSubImage(bImage, rect, destImageFile);
}

/**
  * @Description: 对原始图片根据(x, y, width, height) = (0, 0, width, height)进行缩放，生成BufferImage
  * @param img
  * @param width 预处理后图片的宽度
  * @param height 预处理后图片高度
  * @return
  * @author Sun Yanjun
  * @throws IOException
  */
private static BufferedImage makeThumbnail(Image img, int width, int height) throws IOException {
  BufferedImage tag = new BufferedImage(width, height, 1);
  Graphics g = tag.getGraphics();
  g.drawImage(img.getScaledInstance(width, height, 4), 0, 0, null);
 
  g.dispose();
  return tag;
}

/**
  * @Description: 对BufferImage按照(x, y, width, height) = (subImageBounds.x, subImageBounds.y, subImageBounds.width, subImageBounds.height)进行裁剪
  *               如果subImageBounds范围过大，则用空白填充周围的区域。
  *             
  * @param image
  * @param subImageBounds
  * @param destImageFile
  * @throws IOException
  * @author Sun Yanjun
  */
private static void saveSubImage(BufferedImage image, Rectangle subImageBounds, File destImageFile) throws IOException {
  String fileName = destImageFile.getName();
  String formatName = fileName.substring(fileName.lastIndexOf('.') + 1);
  BufferedImage subImage = new BufferedImage(subImageBounds.width, subImageBounds.height, 1);
  Graphics g = subImage.getGraphics();
 
 
  if ((subImageBounds.width > image.getWidth())
    || (subImageBounds.height > image.getHeight())) {
   int left = subImageBounds.x;
   int top = subImageBounds.y;
   if (image.getWidth() < subImageBounds.width)
    left = (subImageBounds.width - image.getWidth()) / 2;
   if (image.getHeight() < subImageBounds.height)
    top = (subImageBounds.height - image.getHeight()) / 2;
   g.setColor(Color.white);
   g.fillRect(0, 0, subImageBounds.width, subImageBounds.height);
   g.drawImage(image, left, top, null);
   ImageIO.write(image, formatName, destImageFile);
  } else {
   g.drawImage(image.getSubimage(subImageBounds.x, subImageBounds.y,
     subImageBounds.width, subImageBounds.height), 0, 0, null);
  }
  g.dispose();
  ImageIO.write(subImage, formatName, destImageFile);
}
}

//3.一个域对象，获取剪切信息

/**
* by lin
*/
package syj.vo;

public class ImageVo {

    private int txt_width;
    private int txt_height;
    private int txt_top;
    private int txt_left;
    private int txt_DropWidth;
    private int txt_DropHeight;
    private float imageZoom;
    private String picture;
  
public int getTxt_width() {
  return txt_width;
}
public void setTxt_width(int txtWidth) {
  txt_width = txtWidth;
}
public int getTxt_height() {
  return txt_height;
}
public void setTxt_height(int txtHeight) {
  txt_height = txtHeight;
}
public int getTxt_top() {
  return txt_top;
}
public void setTxt_top(int txtTop) {
  txt_top = txtTop;
}
public int getTxt_left() {
  return txt_left;
}
public void setTxt_left(int txtLeft) {
  txt_left = txtLeft;
}
public int getTxt_DropWidth() {
  return txt_DropWidth;
}
public void setTxt_DropWidth(int txtDropWidth) {
  txt_DropWidth = txtDropWidth;
}
public float getImageZoom() {
  return imageZoom;
}
public void setImageZoom(float imageZoom) {
  this.imageZoom = imageZoom;
}
public void setPicture(String picture) {
  this.picture = picture;
}
public String getPicture() {
  return picture;
}
public void setTxt_DropHeight(int txt_DropHeight) {
  this.txt_DropHeight = txt_DropHeight;
}
public int getTxt_DropHeight() {
  return txt_DropHeight;
}
}