struts2，spring和hibernate集成实现图片上传下载的一个小示例

package com.bdqn.hr.util; import java.awt.Color; import java.awt.Graphics2D; import java.awt.Image; import java.awt.image.BufferedImage; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.ByteArrayOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import javax.imageio.ImageIO; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.sun.image.codec.jpeg.JPEGCodec; import com.sun.image.codec.jpeg.JPEGImageEncoder; public class FileUtil { private static Log log = LogFactory.getLog(FileUtil.class); public static byte[] toByteArray(File photo) throws IOException { FileInputStream fis = new FileInputStream(photo); BufferedInputStream bis = new BufferedInputStream(fis); ByteArrayOutputStream baos = new ByteArrayOutputStream(); int c = bis.read(); while (c != -1) { baos.write(c); c = bis.read(); } bis.close(); byte[] rtn = baos.toByteArray(); baos.close(); return rtn; } public static byte[] buildThumbnail(File srcFile) { byte[] rtn = null; try { Image src = ImageIO.read(srcFile); // 构造Image对象 int oldWidth = src.getWidth(null); // 得到源图宽 int oldHeight = src.getHeight(null);// 得到源图高 log.debug("old width is " + oldWidth); log.debug("old height is " + oldHeight); float divWidth = 200f; // 限制宽度为200 int newWidth = 200; // 缩略图宽, int newHeight = 0; // 缩略图高 float tmp; if (oldWidth > newWidth) { tmp = oldWidth / divWidth; newWidth = Math.round(oldWidth / tmp);// 计算缩略图高 newHeight = Math.round(oldHeight / tmp);// 计算缩略图高 log.debug("tmp scale is " + tmp); } else { newWidth = oldWidth; newHeight = oldHeight; } int imageHeight = 100; int imageWidth = 200; log.debug("new width is " + newWidth); log.debug("new height is " + newHeight); BufferedImage bufferedImage = new BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_INT_RGB); Graphics2D graphics2D = (Graphics2D) bufferedImage.createGraphics(); graphics2D.setBackground(Color.WHITE); graphics2D.clearRect(0, 0, imageWidth, imageHeight); bufferedImage.getGraphics().drawImage(src, //(imageWidth - oldWidth) / 2, (imageHeight - newHeight) / 2, 0,0, newWidth, newHeight, null); // 绘制缩小后的图 ByteArrayOutputStream baos = new ByteArrayOutputStream(); BufferedOutputStream bos = new BufferedOutputStream(baos); JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(bos); encoder.encode(bufferedImage); // 近JPEG编码 rtn = baos.toByteArray(); bos.close(); baos.close(); } catch (Exception e) { log.debug(e); } finally { } return rtn; } }