servlet项目demo

页面逻辑

　　页面:首页、登录页面、登录成功页面

　　servlet：登录服务成功跳到登录成功页面

　　filter:判断是否登录。无登录信息跳转到登录页面

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<form action="/loginServlet" method="post">
    请输入账号<input type="text" name="username"><br>
    请输入密码<input type="text" name="password"><br>
    <input type="submit">
    
    
    
</form>
</body>
</html>

登录成功页面

<!--登录成功-->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
success
</body>
</html>

loginfilter.java

package filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebFilter(filterName = "Loginfilter", urlPatterns = {"/*"})
public class loginfilter implements Filter {
    public void destroy() {
    }

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {
        HttpServletRequest reqs = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        System.out.println(" req.getRequestURI() " + reqs.getRequestURI());

        String requestURI = reqs.getRequestURI();
        // 获取请求地址
//        String requestURI = req.getRequestURI().substring(req.getRequestURI().indexOf("/", 1),
//                req.getRequestURI().length());

        // 登陆页面和接口放开限制，否则死循环
        if ("/login.html".equals(requestURI) || "/loginServlet".equals(requestURI)) {
            chain.doFilter(reqs, res);
        } else {
            // 默认不开启
            HttpSession session = reqs.getSession(false);
            // 如果session中没有用户信息，拦截返回登陆页面
            if (session == null || session.getAttribute("username") == null) {
                System.out.println(session);
                res.sendRedirect(reqs.getContextPath() + "/login.html");
                // 返回
                return;
            } else {
                System.out.println(session);
                chain.doFilter(reqs, res);
            }
        }
    }



    public void init(FilterConfig config) throws ServletException {

    }

}

loginServlet.java

package servlet;

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(name = "loginServlet",urlPatterns = "/loginServlet")
public class loginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        System.out.println(username);
//        if(username=="admin" && password=="123"){
        System.out.println(password);
        HttpSession session = request.getSession();//获取session
        session.setAttribute("username",username);
        session.setAttribute("password",password);
        response.sendRedirect(request.getContextPath()+"/success.html");


//        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

代码结构

依赖包:

    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>4.0.1</version>
        <scope>provided</scope>
    </dependency>

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原文地址：https://www.cnblogs.com/ysmdbk/p/11364707.html