编写后端java登录代码
时间: 2023-12-01 19:04:34 浏览: 30
以下是一个简单的Java登录代码,使用Servlet和JSP实现:
LoginServlet.java
```java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class LoginServlet extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
// 进行登录验证
if (username.equals("admin") && password.equals("admin")) {
// 登录成功,将用户名保存到Session中
HttpSession session = request.getSession();
session.setAttribute("username", username);
// 重定向到首页
response.sendRedirect(request.getContextPath() + "/index.jsp");
} else {
// 登录失败,返回登录页面并显示错误信息
request.setAttribute("error", "用户名或密码错误!");
request.getRequestDispatcher("/login.jsp").forward(request, response);
}
}
}
```
login.jsp
```html
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>登录</title>
</head>
<body>
<h1>登录</h1>
<% if (request.getAttribute("error") != null) { %>
<p style="color: red"><%= request.getAttribute("error") %></p>
<% } %>
<form method="post" action="${pageContext.request.contextPath}/LoginServlet">
<label>用户名:</label>
<input type="text" name="username"><br>
<label>密码:</label>
<input type="password" name="password"><br>
<input type="submit" value="登录">
</form>
</body>
</html>
```
在Web.xml中配置Servlet:
```xml
<servlet>
<servlet-name>LoginServlet</servlet-name>
<servlet-class>LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/LoginServlet</url-pattern>
</servlet-mapping>
```
这样就完成了一个简单的Java登录代码。