如何通过一个javascript变量一个Java servlet？

我想一个JavaScript变量传递给一个Java servlet。我开发一个Web应用程序。这是我的HTML code：

I want to pass a javascript variable to a java servlet. I am developing a web application. This is my html code:

<p id="test">Some text</p>

这是我写的JavaScript文件：

And this is what i write in the javascript file:

var myVar = document.getElementById('test').innerText;

$.ajax({
    url: 'Test',
    data: {
        myPostVar: myVar
    },
    type: 'POST'
});

和那么这在servlet（中的doGet）：

And then this in the servlet (in the doGet):

String result = request.getParameter("myPostVar");
System.out.print(result);

，如果我运行Test.java进行测试，它给了我空。我GOOGLE了太多，但找不到任何解决办法。

And if i run the Test.java to test, it gives me "null". I googled too much but could not find any solution.