重庆分公司,新征程启航
为企业提供网站建设、域名注册、服务器等服务
过滤器是什么玩意?
让客户满意是我们工作的目标,不断超越客户的期望值来自于我们对这个行业的热爱。我们立志把好的技术通过有效、简单的方式提供给客户,将通过不懈努力成为客户在信息化领域值得信任、有价值的长期合作伙伴,公司提供的服务项目有:主机域名、虚拟空间、营销软件、网站建设、渭源网站维护、网站推广。
所谓过滤器,其实就是一个服务端组件,用来截取用户端的请求与响应信息。
过滤器的应用场景:
1.对用户请求进行统一认证,保证不会出现用户账户安全性问题
2.编码转换,可在服务端的过滤器中设置统一的编码格式,避免出现乱码
3.对用户发送的数据进行过滤替换
4.转换图像格式
5.对响应的内容进行压缩
其中,第1,2场景经常涉及。
login.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %>My JSP 'login.jsp' starting page
success.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %>My JSP 'index.jsp' starting page
failure.jsp
<%@ page language="java" import="java.util.*" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %>My JSP 'login.jsp' starting page 登录失败,请检查用户名或密码!
LoginFilter.java
package com.cityhuntshou.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 LoginFilter implements Filter { private FilterConfig config; public void destroy() { } public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) arg0; HttpServletResponse response = (HttpServletResponse) arg1; HttpSession session = request.getSession(); //过滤器实际应用场景之二-----编码转换 String charset = config.getInitParameter("charset"); if(charset == null) { charset = "UTF-8"; } request.setCharacterEncoding(charset); String noLoginPaths = config.getInitParameter("noLoginPaths"); if(noLoginPaths != null) { String[] strArray = noLoginPaths.split(";"); for(int i = 0; i < strArray.length; i++) { //空元素,放行 if(strArray[i] == null || "".equals(strArray[i])) continue; if(request.getRequestURI().indexOf(strArray[i]) != -1) { arg2.doFilter(arg0, arg1); return; } } } if(request.getRequestURI().indexOf("login.jsp") != -1 || request.getRequestURI().indexOf("LoginServlet") != -1) { arg2.doFilter(arg0, arg1); return; } if(session.getAttribute("username") != null) { arg2.doFilter(arg0, arg1); } else { response.sendRedirect("login.jsp"); } } public void init(FilterConfig arg0) throws ServletException { config = arg0; } }
LoginServlet.java
package com.cityhuntshou.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class LoginServlet extends HttpServlet { /** * Constructor of the object. */ public LoginServlet() { super(); } /** * Destruction of the servlet.
*/ public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } /** * The doGet method of the servlet.
* * This method is called when a form has its tag value method equals to get. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } /** * The doPost method of the servlet.
* * This method is called when a form has its tag value method equals to post. * * @param request the request send by the client to the server * @param response the response send by the server to the client * @throws ServletException if an error occurred * @throws IOException if an error occurred */ public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); String password = request.getParameter("password"); //new String(username.getBytes("ISO-8859-1"),"UTF-8") System.out.println(username); if("admin".equals(username) && "admin".equals(password)) { //校验通过 HttpSession session = request.getSession(); session.setAttribute("username", username); response.sendRedirect(request.getContextPath()+"/success.jsp"); } else { //校验失败 response.sendRedirect(request.getContextPath()+"/failure.jsp"); } } /** * Initialization of the servlet.
* * @throws ServletException if an error occurs */ public void init() throws ServletException { // Put your code here } }
web.xml
<?xml version="1.0" encoding="UTF-8"?>This is the description of my J2EE component This is the display name of my J2EE component LoginServlet com.cityhuntshou.servlet.LoginServlet LoginServlet /servlet/LoginServlet index.jsp LoginFilter com.cityhuntshou.filter.LoginFilter noLoginPaths login.jsp;failure.jsp;loginServlet charset UTF-8 LoginFilter /*
运行效果:
访问结果:
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持创新互联。