Servlet写的登录页面

最基础的入门级程序。这是一个登录页面。为什么点击提交就出现错误页面。而若没有填写用户名或密码会提示“请填写用户名”之类。求问到底哪里出错啊。


index.html

<!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=gbk">
<title>登录</title>
<script language="javascript" type="">
function LoginSubmit(){
var user=document.Login.loginName.value;
var pass=document.Login.password.value;
if(user==null||user==""){
alert("请填写用户名");
}
else if(pass==null||pass==""){
alert("请填写密码");
}
else document.Login.submit();
}
</script>
</head>
<body>
<form method="POST" name="Login" action="LoginServlet">
<p align="left">
用户名：<input type="text" name="loginName" size="20"></p>
<p align="left">
密 码：<input type="password" name="password" size="20"></p>
<p align="left">
<input type="button" value="提交" name="B1" onclick="LoginSubmit()">
<input type="reset" value="重置" name="B2"></p>
</form>
</body>
</html>


登录的Servlet文件

package com.enter.servlet;

import java.io.IOException;
import java.io.PrintWriter;

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

public class enter extends HttpServlet {
private static final long serialVersionUID = 1L;

public enter() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("GBK");
response.setContentType("text/html;charset=GBK");
PrintWriter out=response.getWriter();
String pass = request.getParameter("password");
String user = request.getParameter("loginName");
if("haier".equals(user) && "soft".equals(pass)){
out.println("登录成功");
}
else{
out.println("登录失败！");
}
}

}