使用JMagicK缩略图片

package cn.js.fan.util;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import magick.ImageInfo;
import magick.MagickException;
import magick.MagickImage;

public class JMagickServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public JMagickServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		doPost(request,response);
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {


		//获取图片URL
		String imageURL = request.getParameter("url");

		//获取服务器保存缩略照片文件夹的路径
		String realURL = this.getServletConfig().getServletContext().getRealPath("/")+"upfile\\wml\\";
		//截取图片的相对路径
		String tempURL = imageURL.substring(imageURL.indexOf("upfile"));
		System.out.println(tempURL.substring(7));
		//组合成文件在服务器的绝对路径
		String str = (tempURL.substring(7)).replaceAll("/", "\\\\");
		//获取原图片的绝对路径
		String str1 = imageURL.substring(imageURL.indexOf("upfile")).replaceAll("/", "\\\\");
		String n_url = this.getServletConfig().getServletContext().getRealPath("/")+str1;
		
		String wapURL = realURL+str;

		if((new File(wapURL).exists())) {//判断该图片是否已经缩小
			System.out.println("该图片已缩小");
			this.imageStream(wapURL, request, response);//输出图像的文件流
			return ;
		}
		
		
		
		
		//获取图片的绝对路径
		String normalPicURL = this.getServletConfig().getServletContext().getRealPath("/")+"upfile\\"+str;
		FileInputStream in = new FileInputStream(normalPicURL);

		BufferedImage bi = ImageIO.read(in);
		int x = bi.getWidth();//获取图片的宽
		int y = bi.getHeight();//获取图片的高
		int narrow_x = 0;
		int narrow_y = 0;

		//判断图片是否需要缩小
		if(x > 120 || y > 120) {
			if(x > y) {
				narrow_y = y/(x/120);
				narrow_x = 120;
			}
			if(y > x) {
				narrow_x = x/(y/120);
				narrow_y = 120;
			}
		}else{
			System.out.println("图片不用缩小");
			this.imageStream(normalPicURL, request, response);//输出图像的文件流
			return;
		}
		
		
		
		
		String [] s = tempURL.split("/");
		String path = "";
		//判断路径上的文件夹是否存在，不存在则创建
		for(int i=1; i<s.length-1; i++) {
			File f2 = new File(realURL+s[i]);
			if(!f2.exists()) {
				f2.mkdir();
			}
			realURL += s[i]+"\\";
			path += s[i]+"/";
			
		}
		//图片生成的路径
		String URL = realURL+s[s.length-1];
		
		System.out.println(n_url);
		//图片进行缩略
		try{
			System.setProperty("jmagick.systemclassloader","no");
			ImageInfo info = new ImageInfo(n_url);
			MagickImage image = new MagickImage(info);
			MagickImage scaleImg = image.scaleImage(narrow_x, narrow_y);
			scaleImg.setFileName(URL);
			scaleImg.writeImage(info);
			scaleImg.destroyImages();
			image.destroyImages();
			this.imageStream(URL, request, response);//输出
			
		}catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	
	public void imageStream(String url,HttpServletRequest request, HttpServletResponse response) {
		try {
			String [] str = url.split("\\.");
			FileInputStream in = new FileInputStream(url);
			
			int i = in.available();
			byte [] data = new byte[i];
			in.read(data);//读取图像数据流
			in.close();

			response.setContentType("image/"+str[str.length-1]);
			OutputStream out = response.getOutputStream();
			out.write(data);//将图像数据写入输出流
			out.close();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

页面显示

<img src="/servlet/JMagickServlet?url=图片路径"/>

如果在多个web都使用 JMagick 时可能会出现 jmagick.dll already loaded in another classloader   的报错，原因是 JVM 已经载入了， 可以把 jmagick.jar 的包 放到 服务器的lib里面去 解决。