关于Servlet的小问题，请大家帮忙，谢谢_Java Web开发

关于Servlet的小问题，请大家帮忙，谢谢

大家好，小弟我学JSP没几天，我目前在学Servlet，下面是我的代码
首先Login如下
<html>
    <head>
    <title>在线图书XX系统</title>
    </head>
    <body>
    <form action="Login" method="get">
        <table>
        <tr>
            <td>用户名：</td>
            <td><input type="text" name="username"></td>
        </tr>
        <tr>
            <td>密码：</td>
            <td><input type="password" name="password"></td>
        </tr>
        <tr>
            <td><input type="reset" value="重填"></td>
            <td><input type="submit" value="提交"></td>
        </tr>
        </table>
    </form>
    </body>
</html>
其次Login.java如下
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;

public class Login extends HttpServlet
{
    private String username = "";
    private String password = "";
    private String inusername = "";
    private String inpassword = "";

    public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException, ServletException
    {
    //HttpSession session = req.getSession();
    //String user = (String)session.getAttribute("user");
    username = getInitParameter("username");
    password = getInitParameter("password");
    inusername = req.getParameter("inusername");
    inpassword = req.getParameter("inpassword");

    resp.setContentType("text/html; charset=gb2312");
    PrintWriter out = resp.getWriter();

    if(inusername == null && inpassword == null && inusername.equals("") && inpassword.equals(""))
    {
        resp.sendRedirect("login");
    }
    else
    {
        if(inusername.equals(username) && password.equals(password))
        {
        out.println("<html><head><title>页面提示</title></head>");
        out.println("<body>抱歉，网站在建设中，近期期待</body>");
        out.println("</html>");
        }
        else
        {
                out.println("<html><head><title>页面提示</title></head>");
        out.println("<body>请输入正确的用户名和密码<br>");
        out.println("<a href" + resp.encodeURL("login") + ">请重新登录</a>");
        out.println("</body>");
        out.println("</html>");

        }
    }
    }
}

再次web.xml如下
<?xml version="1.0" encoding="gb2312"?>

<web-app xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j233
        http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">

    <servlet>
    <servlet-name>LoginServer</servlet-name>
    <servlet-class>Login</servlet-class>
    <init-param>
        <param-name>username</param-name>
        <param-value>shibin</param-value>
        </init-param>

        <init-param>
        <param-name>password</param-name>
        <param-value>1234</param-value>
        </init-param>
    </servlet>

    <servlet-mapping>
    <servlet-name>LoginServer</servlet-name>
    <url-pattern>/login</url-pattern>
    </servlet-mapping>

</web-app>
最后是错误如下：
HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

java.lang.NullPointerException
    Login.doGet(Login.java:25)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:729)

note The full stack trace of the root cause is available in the Apache Tomcat/5.5.30 logs.

--------------------------------------------------------------------------------

Apache Tomcat/5.5.30
请问是什么问题啊

[ 本帖最后由 shiboy3 于 2010-8-24 20:00 编辑 ]

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----------------解决方案--------------------------------------------------------
终于找到问题了，把XML中的/login改成/Login就好，感谢关注过本帖的朋友们
----------------解决方案--------------------------------------------------------
还有就是我怎么感觉你的判断语句顺序是倒过来的呢？ - -！貌似我看错了 ?
----------------解决方案--------------------------------------------------------