工程结构
index.jsp为登陆页面，UserServlet.java为针对登陆的servlet，登陆成功或失败都会跳转到show.jsp，但是有Userfilter.java的过滤。一旦登陆失败会让页面转到error.jsp。
正常是流程：进入index.jsp输入账号密码，登陆成功后进入show.jsp（测试过没问题）
错误的用例：通过控制url绕过index.jsp直接进入show.jsp（出现500错误，应该要进入error.jsp的）
如图
XML配置文件
index.jsp
用户登陆
用户名：
密码：
UserServlet.java
public class UserServlet extends HttpServlet
{
public void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException,IOException
{
String name=req.getParameter("username");
String password=req.getParameter("password");
UserInfo info= new UserInfo();
if(password.equals("123456"))
{
info.setName(name);
info.setPassword(password);
req.getSession().setAttribute("name", name);
req.getSession().setAttribute("userinfo", info);
System.out.println("登陆成功");
RequestDispatcher rd=req.getRequestDispatcher("/hehe/show.jsp");
rd.forward(req, resp);
}
else
{
System.out.println("登录失败");
RequestDispatcher rd=req.getRequestDispatcher("/hehe/show.jsp");
rd.forward(req, resp);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException,IOException
{
doGet(request,response);
}
}
UserFilter.java
public class UserFilter implements Filter{
//销毁方法
public void destroy() {
}
//完成过滤操作
public void doFilter(ServletRequest request, ServletResponse response,FilterChain filter) throws IOException, ServletException
{
UserInfo info=(UserInfo)((HttpServletRequest) request).getSession().getAttribute("userinfo");
String name=((HttpServletRequest) request).getSession().getAttribute("name").toString();
System.out.println("filter 2:"+name);
if(info!=null)
//if(name!=null)
{
filter.doFilter(request, response);
}
else
{
response.setContentType("text/html;charset=utf-8");
((HttpServletResponse) response).sendRedirect("../error.jsp");
}
}
//初始化
public void init(FilterConfig arg0) throws ServletException {
}
}
