登录案例(JDBC+servlet)idea版
需求：
登录界面有用户名输入框，密码输入框，有验证码验证，用户名或密码错误与验证码错误有错误提示，登录成功跳转到成功界面，能获取到用户名
运行界面
包结构
验证码的代码
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
@WebServlet("/verifyServlet")
public class VerifyServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
int width=200;
int height=50;
BufferedImage bi=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取画笔
Graphics g=bi.getGraphics();
//设置颜色
g.setColor(Color.orange);
//填充背景色
g.fillRect(0,0,width,height);
//画边框
g.setColor(Color.white);
g.drawRect(0,0,width-1,height-1);
//生成验证码
Random random=new Random();
String str="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
//用于存储验证码
StringBuilder sb = new StringBuilder();
for (int i = 1; i <= 4 ; i++) {
int num=random.nextInt(str.length());
char ch=str.charAt(num);
sb.append(ch);
g.drawString(ch+"",width/5*i,height/2);
}
String session_checkCode = sb.toString();
//将验证码存储到Session中
request.getSession().setAttribute("session_checkCode",session_checkCode);
//设置干扰线
g.setColor(Color.GREEN);
for (int i = 0; i < 10; i++) {
int x1=random.nextInt(width);
int x2=random.nextInt(width);
int y1=random.nextInt(height);
int y2=random.nextInt(height);
g.drawLine(x1,x2,y1,y2);
}
ImageIO.write(bi,"jpg",response.getOutputStream());
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doPost(request, response);
}
}
登录判断的代码
import shanghai.qf.dao.UserDao;
import shanghai.qf.dao.daoImple.UserDaoImpl;
import shanghai.qf.domain.User;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
String checkCode = request.getParameter("checkCode");
User user=new User();
user.setUsername(username);
user.setPassword(password);
UserDao dao=new UserDaoImpl();
User loginUser = dao.login(user);
HttpSession session = request.getSession();
String session_checkCode = (String)session.getAttribute("session_checkCode");
session.removeAttribute("session_checkCode");
if(session_checkCode!=null && session_checkCode.equalsIgnoreCase(checkCode)){
if(loginUser != null){
session.setAttribute("username",username);
response.sendRedirect(request.getContextPath()+"/success.jsp"); //动态获取路径
}
else {
request.setAttribute("login","用户名或密码错误");
request.getRequestDispatcher("/index.jsp").forward(request,response);
}
}else{
request.setAttribute("cc","验证码错误");
request.getRequestDispatcher("/index.jsp").forward(request,response);
}
}
}
index.jsp代码部分
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
登录页面
<%=request.getAttribute("login")==null?"":request.getAttribute("login") %>
<%=request.getAttribute("cc")==null?"":request.getAttribute("cc") %>
success.jsp代码部分
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
success
<%= request.getSession().getAttribute("username") %> 欢迎你