jsp实现登录验证的过滤器

本文实例为大家分享了jsp实现登录验证的过滤器，供大家参考，具体内容如下

1.新建一个Dynamic Web Project项目，里面新建1个filter文件、1个servlet文件和2个jsp文件，整体的框架如图所示：

2.LoginFilter.java里面的代码如下所示：

package filter;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@WebFilter(filterName = \”loginFilter\”, urlPatterns = { \”/*\” })
public class LoginFilter implements Filter {

public void destroy() {
}

public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
HttpServletRequest req = (HttpServletRequest) request;
HttpServletResponse resp = (HttpServletResponse) response;
HttpSession session = req.getSession(true);
resp.setContentType(\”text/html;\”);
resp.setCharacterEncoding(\”utf-8\”);
PrintWriter out = resp.getWriter();
String request_uri = req.getRequestURI();
String ctxPath = req.getContextPath();
String uri = request_uri.substring(ctxPath.length());
if (uri.contains(\”login.jsp\”) || uri.contains(\”loginServlet\”)) {
chain.doFilter(request, response);
} else {
if (session.getAttribute(\”user\”) != null) {
chain.doFilter(request, response);
} else {
out.println(\”您没有登录，请先登录！3秒后回到登录页面。\”);
resp.setHeader(\”refresh\”, \”3;url=\” + ctxPath + \”/login.jsp\”);
return;
}
}
}

public void init(FilterConfig fConfig) throws ServletException {
}

}

3.LoginServlet.java里面的代码如下所示：

package servlet;

import java.io.IOException;

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;

@WebServlet(name = \”loginServlet\”, urlPatterns = { \”/loginServlet\” })
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

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

protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter(\”name\”);
String password = request.getParameter(\”pwd\”);
if (\”filter\”.equals(username) && \”filter\”.equals(password)) {
HttpSession session = request.getSession(true);
session.setAttribute(\”user\”, username);
response.sendRedirect(\”loginSuccess.jsp\”);
} else {
response.sendRedirect(\”login.jsp\”);
}
}

}

4.login.jsp里面的代码如下所示：

<%@page import=\”java.util.Date\”%>
<%@ page language=\”java\” contentType=\”text/html; charset=UTF-8\”
pageEncoding=\”UTF-8\”%>
<!DOCTYPE html PUBLIC \”-//W3C//DTD HTML 4.01 Transitional//EN\” \”http://www.w3.org/TR/html4/loose.dtd\”>
<html>
<head>
<meta http-equiv=\”Content-Type\” content=\”text/html; charset=UTF-8\”>
<title>example</title>
</head>
<body bgcolor=\”lightPink\”>
<form action=\”loginServlet\” method=\”post\”>
<table>
<tr>
<td>用户名：</td>
<td><input type=\”text\” name=\”name\” /></td>
</tr>
<tr>
<td>密码：</td>
<td><input type=\”password\” name=\”pwd\” />
</tr>
<tr>
<td><input type=\”submit\” value=\”提交\” /></td>
<td><input type=\”reset\” value=\”重置\” /></td>
</tr>
</table>
</form>
</body>
</html>