java - JSTL sql :query variable

Question

我在 JSP 文件中编写了以下代码:

<c:catch var="e">
    <%
        int accountNumber = Integer.parseInt(request.getParameter("accountNumber"));
        int depositAmount = Integer.parseInt(request.getParameter("depositAmount"));
    %>
    <sql:query var='account' dataSource="jdbc/bank">
        select * from account where AccountNumber=<%= accountNumber %>      
    </sql:query>
    <c:choose>
        <c:when test="${account.first() == false}">
            <p>Account not found</p>
        </c:when>
        <c:otherwise>
            <h3>Deposit Made</h3>
            <p>Account number: <%= accountNumber %></p>
            <p>Deposit amount: <%= depositAmount %></p>
            <p>New balance: </p>
        </c:otherwise>
    </c:choose>
</c:catch>


<c:if test="${e != null}">
    error
</c:if>

我遇到的问题是以下代码抛出 javax.el.MethodNotFoundException: Unable to find method [first] with [0] parameters 异常:

<c:when test="${account.first() == false}">
  <p>Account not found</p>
</c:when>

我需要访问 sql:query 中的帐户变量，以便检查第一行是否存在。

Answer 1

<sql:query var='account' dataSource="jdbc/bank">

根据 <sql:query> documentation , account是 javax.servlet.jsp.jstl.sql.Result class .

<c:when test="${account.first() == false}">

根据类的 javadoc，该类没有 first()方法。但是有一个 getRowCount() method .我建议改用它。

<c:when test="${account.rowCount == 0}">