同学们再做计算机毕业设计的时候,JSP会是很多软件工程专业的首选,JAVA作为一个面向对象高级语言,拥有强大的功能, 但是在学习难度上也是客观存在的,有很多同学到了大四还是无法完整的写一份代码,今天给同学们分享一下如何使用SERVLET实现登录验证,麻雀虽小五脏俱全,希望同学们能从小的知识点去理解JAVA,理解SEVLET,做好自己的毕业设计
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: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 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 { } } 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"); } } }
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