servlet串行拦截器实现例子

至于串行过滤器有什么作用，我实在不知。我的理解是它只是说明过滤器的串行运行方式

需求：当用户没有登录访问更新页面的时候，跳转到登录页面

1.登录页面：login.jsp

<%@ 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>Insert title here</title>
</head>
<body>
<form action="UserLoginServlet" method="post">username:<input type="text" value="<%=null == request.getAttribute("username")?"" : request.getAttribute("username") %>" name="username"><br>password:<input type="text" name="password"><br>authority:<select  name="authority"><option value="1" <%="1".equals(request.getAttribute("authority"))?"selected = selected" : "" %>>common user</option><option value="2" <%="2".equals(request.getAttribute("authority"))?"selected = selected" : "" %>>adminstrator</option></select><br><input type="submit">
</form></body>
</html>

2.登录页面的servet容器

package com.filter;import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;import com.javabean.User;public class UserLoginServlet extends HttpServlet
{@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{String username = (String)req.getParameter("username");String password = (String)req.getParameter("password");String authority = (String)req.getParameter("authority");if("1".equals(authority) && "zhangsan".equals(username) && "123".equals(password)){User user = new User();user.setUsername(username);user.setPassword(password);user.setAuthority(authority);HttpSession session = req.getSession();session.setAttribute("user",user);req.getRequestDispatcher("index.jsp").forward(req, resp);return ;}if("2".equals(authority) && "lisi".equals(username) && "456".equals(password)){User user = new User();user.setUsername(username);user.setPassword(password);user.setAuthority(authority);HttpSession session = req.getSession();session.setAttribute("user",user);req.getRequestDispatcher("index.jsp").forward(req, resp);return ;}System.out.println("meiyou denglu");resp.sendRedirect("login.jsp?error=true&username="+username+"&authority="+authority);}}

UserLoginServlet

3.主页面index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8"%><%@ page import="com.javabean.User" %>
<!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>Insert title here</title>
</head>
<body>
<a href="QueryServletFilter">query</a><br>
<%
User user = (User)session.getAttribute("user");
if(null == user)
{response.sendRedirect("login.jsp");return;
}if("2".equals(((User)session.getAttribute("user")).getAuthority())){%>
<a href="UpdateServletFilter">update</a><%} %>
</body>
</html>

index.jsp

4.查询servlet. QueryServletFilter

package com.filter;import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class QueryServletFilter extends HttpServlet
{@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{System.out.println("QueryServletFilter run");}
}

View Code

5.更新servlet容器. UpdateServletFilter

package com.filter;import java.io.IOException;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;public class UpdateServletFilter extends HttpServlet
{@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException{System.out.println("UpdateServletFilter run");}
}

UpdateServletFilter

6.web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5"><display-name>filter</display-name><servlet><servlet-name>UserLoginServlet</servlet-name><servlet-class>com.filter.UserLoginServlet</servlet-class></servlet><servlet-mapping><servlet-name>UserLoginServlet</servlet-name><url-pattern>/filter/UserLoginServlet</url-pattern></servlet-mapping><servlet><servlet-name>QueryServletFilter</servlet-name><servlet-class>com.filter.QueryServletFilter</servlet-class></servlet><servlet-mapping><servlet-name>QueryServletFilter</servlet-name><url-pattern>/filter/QueryServletFilter</url-pattern></servlet-mapping><servlet><servlet-name>UpdateServletFilter</servlet-name><servlet-class>com.filter.UpdateServletFilter</servlet-class></servlet><servlet-mapping><servlet-name>UpdateServletFilter</servlet-name><url-pattern>/filter/UpdateServletFilter</url-pattern></servlet-mapping><!-- filter start --><filter><description>this is the servlet filter example</description><filter-name>userLoginServletFilter1</filter-name><filter-class>com.filter.UserLoginServletFilter</filter-class></filter><!-- 演示过滤器串行运行 --><filter><description>this is the servlet filter example</description><filter-name>userLoginServletFilter2</filter-name><filter-class>com.filter.UserLoginServletFilter2</filter-class></filter><!-- url-pattern表示只过滤 UpdateServletFilter这一个servlet容器--><filter-mapping><filter-name>userLoginServletFilter1</filter-name><url-pattern>/filter/UpdateServletFilter</url-pattern></filter-mapping><!-- url-pattern表示只过滤 UpdateServletFilter这一个servlet容器--><filter-mapping><filter-name>userLoginServletFilter2</filter-name><url-pattern>/filter/UpdateServletFilter</url-pattern></filter-mapping><!-- filter end -->
</web-app>

web.xml

7.filter拦截器 UserLoginServletFilter

package com.filter;import java.io.IOException;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.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;public class UserLoginServletFilter implements Filter
{@Overridepublic void destroy(){System.out.println("destroy");}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain filterChain) throws IOException, ServletException{HttpServletRequest req = (HttpServletRequest)request;HttpSession s = req.getSession();if(req.getRequestURI().endsWith("login.jsp") || req.getRequestURI().endsWith("UserLoginServlet")){System.out.println("Filter1 start");filterChain.doFilter(request, response);System.out.println("filter1 end");return ;}if(null ==  s.getAttribute("user")){System.out.println("Filter1 start..");((HttpServletResponse)response).sendRedirect("login.jsp");return;}else{System.out.println("Filter1 start....");filterChain.doFilter(request, response);}}@Overridepublic void init(FilterConfig filterConfig) throws ServletException{System.out.println("init");}}

UserLoginServletFilter

8.filter拦截器2 UserLoginServletFilter2

package com.filter;import java.io.IOException;import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;public class UserLoginServletFilter2 implements Filter
{@Overridepublic void destroy(){System.out.println("destory2");}@Overridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain filterChain) throws IOException, ServletException{System.out.println("doFilter2 start");filterChain.doFilter(request, response);System.out.println("doFilter2 end");}@Overridepublic void init(FilterConfig arg0) throws ServletException{System.out.println("init2");}}

UserLoginServletFilter2

web.xml中url-pattern属性值表示访问的路径。

转载于:https://www.cnblogs.com/feiguo/p/3804019.html

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