jsp里怎么取js里变量值

<!-- index.jsp -->
<form action="process.jsp" method="post">
    <input type="hidden" id="hiddenField" name="jsValue">
    <button type="submit">Submit</button>
</form>

<script>
    // 假设这是你的JavaScript变量
    var jsVar = "Hello from JavaScript";
    document.getElementById('hiddenField').value = jsVar;
</script>

<!-- process.jsp -->
<%
    String valueFromJS = request.getParameter("jsValue");
    out.println("Value from JavaScript: " + valueFromJS);
%>

<!-- index.jsp -->
<button onclick="sendData()">Send Data</button>

<script>
    function sendData() {
        var jsVar = "Hello from JavaScript";
        var xhr = new XMLHttpRequest();
        xhr.open("POST", "process.jsp", true);
        xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        xhr.send("jsValue=" + encodeURIComponent(jsVar));
    }
</script>

<!-- process.jsp -->
<%
    String valueFromJS = request.getParameter("jsValue");
    out.println("Value from JavaScript: " + valueFromJS);
%>

<!-- index.jsp -->
<a href="process.jsp?jsValue=Hello%20from%20JavaScript">Send Data</a>

<script>
    var jsVar = "Hello from JavaScript";
    window.location.href = "process.jsp?jsValue=" + encodeURIComponent(jsVar);
</script>

<!-- process.jsp -->
<%
    String valueFromJS = request.getParameter("jsValue");
    out.println("Value from JavaScript: " + valueFromJS);
%>