eclipse导入rt包问题
copy了一份别人写的生成验证码的servlet，却发现编译时不能通过，提示找不到sun.image.codec.jpeg.JPEGCodec和com.sun.image.codec.jpeg.JPEGImageEncoder。其servlet如下。最后，通过将jre lib目录下的rt.jar拷贝到工程，然后引入，得以通过。
package com.jesse.onlineshop.servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.util.Random;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;public class GenerateIdentifyCodeServlet extends HttpServlet {private static final long serialVersionUID = -5083098939508150302L;private static Random random = new Random();private static final char[] stores = { '1', '2', '3', '4', '5', '6', '7','8', '9', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K','L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y','Z' };public String getRandonString() {StringBuffer buff = new StringBuffer();for (int i = 0; i < getLength(); i++) {buff.append(stores[random.nextInt(stores.length)]);}return buff.toString();}public Color getRandomColor() {return new Color(random.nextInt(255), random.nextInt(255),random.nextInt(255));}public Color getReverseColor(Color color) {return new Color(255 - color.getRed(), 255 - color.getGreen(),255 - color.getBlue());}@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {int width = 100;int height = 30;resp.setContentType("image/jpeg");String randomString = getRandonString();req.getSession(true).setAttribute("identifyCode", randomString);Color color = getRandomColor();Color reverse = getReverseColor(color);BufferedImage bi = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics2D g = bi.createGraphics();g.setFont(new Font(Font.SANS_SERIF, Font.BOLD, 16));g.setColor(color);g.fillRect(0, 0, width, height);g.setColor(reverse);g.drawString(randomString, 18, 20);for (int i = 0, n = random.nextInt(width); i < n; i++) {g.drawRect(random.nextInt(width), random.nextInt(height), 1, 1);}ServletOutputStream out = resp.getOutputStream();JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);encoder.encode(bi);out.flush();out.close();}public int getLength() {return Integer.parseInt(getInitParameter("codelength"));}}