如何在JSP中访问JavaScript变量值?

问题描述

function modification()
{

  alert(document.getElementById("record").value);
  var rec=document.getElementById("record").value;
  <%
  Connection connect = DriverManager.getConnection("jdbc:odbc:DSN","scott","tiger");
  Statement stm=connect.createStatement();
  String record=""; // I want value of "rec" here.

  ResultSet rstmt=stm.executeQuery("select * from "+record);
  %>
}

推荐答案

请记住，示例中的JavaScript正在浏览器的 client 上运行； JSP代码正在服务器上运行.要访问服务器上的客户端数据，必须将其从客户端发送到服务器，您不能像示例中那样内联访问.通常，这是通过提交表单或执行 Ajax请求来完成的.

Remember that the JavaScript in your example is running on the client, in the browser; the JSP code is running on the server. To access client-side data on the server, you have to send it from the client to the server, you can't access it inline as in your example. This is usually done by submitting a form or doing an Ajax request.

例如，使用原型，您的modification函数可能如下所示:

For instance, using Prototype, your modification function might look like this:

function modification()
{
  var rec=document.getElementById("record").value;
  new Ajax.Request("modifyRecord.jsp", {
    parameters: {rec: rec},
    onFailure:  showUpdateFailure
  });
}

function showUpdateFailure(response) {
  /* ...code here to show that the update failed... */
}

或者使用 jQuery ，它看起来可能像这样:

Or using jQuery, it might look like this:

function modification()
{
  var rec=document.getElementById("record").value;
  $.ajax({
    url: 'modifyRecord.jsp',
    data: {rec: rec},
    error: showUpdateFailure
  });
}

function showUpdateFailure(xhr, errmsg) {
  /* ...code here to show that the update failed... */
}

无论哪种方式，您的ModifyRecord.jsp都会收到一个POST参数rec，该参数可用于执行数据库操作(在小心防御 SQL注入攻击).

Either way, your modifyRecord.jsp would receive a POST parameter rec which it could use to perform a database operation (after being careful to defend against SQL injection attacks).

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