这是我的jQuery代码：

<script type="text/javascript">
$(function(){
$("#subBtn").bind("click",function(){
$.ajax({
type:"post",
url:"registerServlet",
data:{"value":"tom"},
})
})
})
</script>

jsp部分代码：

<form action="" method="post" name="registerForm">
<table align="center">
<tr>
<td>学&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;号: </td>
<td>
<input type="text" name="stu_num"/>
</td>
</tr>
<tr>
<td>学生姓名: </td>
<td>
<input type="text" name="stu_name"/>
</td>
</tr>
<tr>
<td>学生性别: </td>
<td>
<input type="text" name="stu_sex"/>
</td>
</tr>
<tr>
<td>出生日期: </td>
<td>
<input type="text" name="stu_birthday">
</td>
</tr>
<tr>
<td>学生年龄: </td>
<td>
<input type="text" name="stu_age"/>
</td>
</tr>
<tr>
<td>住&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;址: </td>
<td>
<input type="text" name="stu_address"/>
</td>
</tr>
<tr><td align="center" colspan="2">
<button id="subBtn" >注册</button>
</td></tr>
</table>
</form>

Servlet代码：

public void doPost(HttpServletRequest request,HttpServletResponse response)
throws ServletException,IOException {
request.setCharacterEncoding("UTF-8");
String value=request.getParameter("value");
System.out.println(value);
}

web.xml文件：

<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>registerServlet</servlet-name>
<servlet-class>mcmin.Servlet.registerServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>registerServlet</servlet-name>
<url-pattern>/registerServlet</url-pattern>
</servlet-mapping>

点击button后，后台就是取不到value的值，这是为什么，解决办法又是什么啊，自学好多不懂啊，大神指教！