分析
LoginServlet类
@WebServlet("/loginServlet") public class LoginServlet extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置request编码 request.setCharacterEncoding("utf-8"); //获取参数 String username = request.getParameter("username"); String password = request.getParameter("password"); String checkcode = request.getParameter("checkcode"); //判断验证码是否正确 HttpSession session = request.getSession(); //获取验证码的值 String checkCode_session = (String) session.getAttribute("checkCode"); //一获取完，就立马删除，以保证验证码的一次性 session.removeAttribute("checkCode"); if (checkCode_session!=null&&checkCode_session.equalsIgnoreCase(checkcode)){//忽略大小写比较 //验证码正确 //1.判断验证码和密码是否一致 if ("zhangsan".equals(username)&&"123".equals(password)){//完善是需要调用userDao查询数据库的 //登陆成功 //1.存储用户信息 session.setAttribute("user",username); //2.重定向success.jsp response.sendRedirect(request.getContextPath()+"/success.jsp"); }else { //登陆失败 //1.存储信息到request域中 request.setAttribute("login_error","用户名或密码 不正确"); //2.转发 request.getRequestDispatcher("/login.jsp").forward(request,response); } }else { //验证码不正确 //1.存储信息到request域中 request.setAttribute("cc_error","验证码不正确"); //2.转发 request.getRequestDispatcher("/login.jsp").forward(request,response); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } }
验证码类Servlet
@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width=100;
int height=50;
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g = image.getGraphics();
g.setColor(Color.green);
g.drawRect(0,0,width,height);
g.setColor(Color.yellow);
g.fillRect(0,0,width-1,height-1);
String str="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
Random random=new Random();
g.setColor(Color.magenta);
StringBuilder sb = new StringBuilder();
for (int i=1;i<=4;i++){
int index = random.nextInt(str.length());
char ch=str.charAt(index);
g.drawString(ch+"",i*width/5,height/2);
sb.append(ch);
}
String checkCode_session = sb.toString();
HttpSession session=request.getSession();
session.setAttribute("checkCode",checkCode_session);
System.out.println("验证码是 : " + checkCode_session);
//画干扰线
g.setColor(Color.green);
for (int i = 0; i < 16; i++) {
int x1=random.nextInt(width);
int x2=random.nextInt(width);
int y1=random.nextInt(height);
int y2=random.nextInt(height);
g.drawLine(x1,y1,x2,y2);
}
ImageIO.write(image,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>login</title> <script> window.onload=function () { var img = document.getElementById('img'); img.onclick=function () { var date=new Date().getTime(); // img.src="/session/checkCodeServlet?"+date this.src="/session/checkCodeServlet?time="+date } } </script> <style> div{ color: red; } </style> </head> <body> <form action="/session/loginServlet"> <table> <tr> <td>用户名</td> <td><input type="text" name="username"></td> </tr> <tr> <td>密码</td> <td><input type="password" name="password"></td> </tr> <tr> <td>验证码</td> <td><input type="text" name="checkcode"></td> </tr> <tr> <td colspan="2"><img id="img" src="/session/checkCodeServlet"></td> </tr> <tr> <td colspan="2"><input type="submit" value="登录"></td> </tr> </table> </form> <div><%= request.getAttribute("login_error")==null?"":request.getAttribute("login_error")%></div> <div><%= request.getAttribute("cc_error")==null?"":request.getAttribute("cc_error")%></div> </body> </html>
success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>登录成功</title> </head> <body> 欢迎登录，<h1><%=request.getSession().getAttribute("user") %></h1> </body> </html>