java 开发web跳转到loginservlet提示404

[qq_18302955]

<form action="${pageContext.request.contextPath}/servlet/LoginServlet" >
<input type="submit" value="登录" onclick="return validateLogin()" />
</form>
<script language="javascript">
function validateLogin() {
var userName = document.getElementById("uname").value;
var pwd = document.getElementById("pwd").value;
if (userName == "") {
alert("请输入用户名");
return false;
} else if (pwd == "") {
alert("请输入用户名和密码");
return false;
}
}
</script>

为什么每次点击登录按钮时都提示我404 呢？web.xml中LoginServlet我也配置好了啊，每次都提示404.求助大神

[JR_Lin_520]

<form action="${pageContext.request.contextPath}/servlet/LoginServlet" > <input type="text" id="Username" name="Username"> <input type="password" id="pwd" name="pwd"> <input type="submit" value="登录" onclick="return validateLogin()" /> </form> <script type="text/javascript"> function validateLogin() { var userName = document.getElementById(Username").value; var pwd = document.getElementById("pwd").value; if (userName == "") { alert("请输入用户名"); return false; } else if (pwd == "") { alert("请输入用户名和密码"); return false; } } </script> 你按这样子运行看看，你用Username=document.getElementById("Username").value之前因先用HTML写一个“text”框