Filter案例

package com.gqx.demo1;

import java.io.IOException;

import java.io.PrintWriter;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.ArrayList;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class AuthorityServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        String methodName=request.getParameter("method");

        //为了让一个servlet响应多个请求，这里可以使用反射

        try {

            Method method=getClass().getMethod(methodName, HttpServletRequest.class,HttpServletResponse.class);

            method.invoke(this, request,response);

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        this.doGet(request, response);

    }

    private UserDao userDao=new UserDao();

    //获取用户所有的信息

    public void getAuthorities(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        String userName=request.getParameter("username");

        User user =userDao.get(userName);

        request.setAttribute("user", user);

        request.setAttribute("authorities", userDao.getAuthorities());

        request.getRequestDispatcher("/authority-manager.jsp").forward(request, response);

    }

    public void updateAuthority(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        String username = request.getParameter("username");

            String [] authorities = request.getParameterValues("authority");

            List<Authority> authorityList = userDao.getAuthorities(authorities);

            userDao.update(username, authorityList);

            response.sendRedirect(request.getContextPath() + "/authority-manager.jsp");

    }

}