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Web过滤器技术的应用1.检测用户是否登陆2.过滤字符集

2016-03-04 18:13 555 查看 
<pre name="code" class="java"><%@ 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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="LoginServlet" method="post">
用户名：<input type="text" name="username" /> 密码：<input type="password"
name="password" /> <input type="submit" value="提交" />
</form>
</body>
</html>



<pre name="code" class="java">package com.sun.filter;

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;

/**
* Servlet implementation class LoginServlet
*/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

/**
* @see HttpServlet#HttpServlet()
*/
public LoginServlet() {
super();
// TODO Auto-generated constructor stub
}

/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
doPost(request, response);
}

/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
String username = request.getParameter("username");
String password = request.getParameter("password");
System.out.println("username:" + username);
if("admin".equals(username)&&"admin".equals(password)){
request.getSession().setAttribute("username", username);
response.sendRedirect("success.jsp");
}else{
response.sendRedirect("fail.jsp");
}
}

}



package com.sun.filter;

import java.io.IOException;

import javax.servlet.DispatcherType;
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.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebFilter(filterName = "LoginFilter", urlPatterns = { "/*" }, dispatcherTypes = { DispatcherType.REQUEST,
DispatcherType.ASYNC }, initParams = {
@WebInitParam(name = "noFilterPath", value = "login.jsp;fail.jsp;LoginServlet"),
@WebInitParam(name = "charset", value = "utf-8") })
public class LoginFilter implements Filter {
private FilterConfig config;
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2)
throws IOException, ServletException {
// TODO Auto-generated method stub
HttpServletRequest request = (HttpServletRequest) arg0;
HttpServletResponse response = (HttpServletResponse) arg1;
request.setCharacterEncoding(config.getInitParameter("charset"));//通过初始化参数配置字符集
System.out.println("url:" + request.getRequestURI());
// 在实际项目开发过程中，用户没有登陆，不允许访问的页面有过个，为了避免麻烦的配置urlPatterns,
// 可以使用filterConfig来初始化哪些jsp不用过滤，url包含这些jsp的时候直接放行
String noFilterPaths = config.getInitParameter("noFilterPath");
if (noFilterPaths != null) {
String[] strArray = noFilterPaths.split(";");
for (int i = 0; i < strArray.length; i++) {
if (request.getRequestURI().indexOf(strArray[i]) != -1) {
System.out.println(strArray[i] + "  放行");
arg2.doFilter(arg0, arg1);// 放行
return;
}
}
}
if (request.getSession().getAttribute("username") != null) {
System.out.println("已经登陆放行");
arg2.doFilter(arg0, arg1);// 放行
} else {
response.sendRedirect("login.jsp");// 到登陆界面
System.out.println("到登陆界面");
}
}

@Override
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
config = arg0;
}

}

                                            

                                        

                        
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