String imgcode = (String) request.getSession().getAttribute("imgcode");
if(checkcode != null && imgcode !=null && checkcode.equals(imgcode)){
// 与数据库比较，判断用户是否存在
User entity = userService.login(name, pass);
if (entity == null) {
response.sendRedirect("./error.jsp");
} else {
// 这里用到了请求域
request.setAttribute("user", entity);
request.getRequestDispatcher("./success.jsp").forward(request,
response);
}
}else{
response.getWriter().print("验证码错误！！！");
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
验证码：
package com.csdn.servlet;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckCode extends HttpServlet {
private static final int WIDTH = 130;
private static final int HEIGHT = 30;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 1.创建图片
BufferedImage image = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);
// 2.得到图片
Graphics g = image.getGraphics();
// 3 对图片进行绘制
// a.设置图片的背景色
setBackGround(g);
// c.添加干扰线
setRandomLine(g);
// g.向图形中写数据
String checkcode = setRandomNum(g);
request.getSession().setAttribute("imgcode", checkcode);
// 4.把图片写给浏览器
response.setContentType("image/jpeg");
// 告诉浏览器不要缓存
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setIntHeader("Expires", -1);
ImageIO.write(image, "JPEG", response.getOutputStream());
}
private String setRandomNum(Graphics g) {
g.setFont(new Font("宋体", Font.BOLD, 25));
Random random = new Random();
StringBuffer sb = new StringBuffer();
int x = 10;
for (int i = 0; i < 4; i++) {
// 产生随机数
String str = String.valueOf(random.nextInt(10));
sb.append(str);
g.setColor(new Color(random.nextInt(255), random.nextInt(255),
random.nextInt(255)));
int degree = random.nextInt() % 30;
((Graphics2D) g).rotate(degree * Math.PI / 180, x, 20);
g.drawString(str, x, 20);
((Graphics2D) g).rotate(-degree * Math.PI / 180, x, 20);
x += 30;
}
return sb.toString();
}
private void setRandomLine(Graphics g) {
g.setColor(Color.green);
Random random = new Random();
for (int i = 0; i < 5; i++) {
int x1 = random.nextInt(WIDTH);
int y1 = random.nextInt(HEIGHT);
int x2 = random.nextInt(WIDTH);
int y2 = random.nextInt(HEIGHT);
g.drawLine(x1, y1, x2, y2);
}
}
private void setBackGround(Graphics g) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
package com.csdn.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import jav