validatefilter.java

java/servlet好麻烦啊,只是想下载点东西

package com;

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.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class ValidateFilter extends HttpServlet implements Filter {
	public void init(FilterConfig arg0) throws ServletException {		
	}
	
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain filterChain) throws IOException, ServletException {
		// 获得HttpSession对象
		HttpSession session = ((HttpServletRequest) request).getSession();
		try {
			System.out.println("进入ValidateFilter过滤器");
			UserDto userDto = (UserDto) session.getAttribute("userDto");
			String userType = userDto.getUserType();
			String requestUri = ((HttpServletRequest) request).getRequestURI();
			
			// 当用户为普通用户且想访问page2.jsp或page3.jsp时将抛出异常
			if (userType.equals("普通用户")
					&& (requestUri.equals("/JSP_E1/page/page2.jsp") || requestUri
							.equals("/JSP_E1/page/page3.jsp"))) {
				String message = "普通用户不能访问在校学生及系统管理员页面";
				session.setAttribute("message", message);				
				throw new Exception(message);
			}
			// 当用户为在校学生且想访问page3.jsp时将抛出异常
			if (userType.equals("在校学生")
					&& requestUri.equals("/JSP_E1/page/page3.jsp")) {
				String message = "在校学生不能访问系统管理员页面";
				session.setAttribute("message", message);
				throw new Exception(message);
			}
			filterChain.doFilter(request, response);
		} catch (Exception e) {	
			System.out.println(e.getMessage());
			// 当超出访问权限时转到error.jsp错误页面
			((HttpServletResponse) response).sendRedirect("/JSP_E1/error.jsp");
		}
	}

}