Question

我正在尝试根据用户输入从数据库中获取数据，以便用户可以跟踪订单。该文件在IDE中编译良好，但在浏览器中抛出此错误：

javax.servlet.ServletException：java.sql.SQLException：ResultSet关闭后不允许操作

form.jsp

<form action="viewOrderHistory" method="Post" id="invoiceNumberLookup">
            Invoice Number:
            <BR><BR>
            <INPUT TYPE="TEXT" NAME="invoice_number">
            &nbsp;
            <INPUT TYPE="SUBMIT" value="View Order">
        </form>


            <form action="viewOrderHistory" method="Post" id="referenceNumberLookup">
            Reference Number:
            <BR><BR>
            <INPUT TYPE="TEXT" NAME="reference_number">
            &nbsp;
            <INPUT TYPE="SUBMIT" value="View Order">
        </form>

result.jsp中

<%@ page import="java.sql.*" %>

<HTML>
    <HEAD>
        <TITLE>Fetching Data From a Database</TITLE>
    </HEAD>

    <BODY>
        <H1>Fetching Data From a Database</H1>

        <% 
            Connection connection = DriverManager.getConnection(
                "jdbc:mysql://localhost/app?user=root&password=password");

            Statement statement = connection.createStatement();

            String first_name = request.getParameter("first_name");
            String last_name= request.getParameter("last_name");

            String invoice_number = request.getParameter("invoice_number");
            String reference_number = request.getParameter("reference_number");
            String amount = request.getParameter("amount");
            String status= request.getParameter("status");
            String date_created = request.getParameter("date_created");
            String quantity = request.getParameter("quantity");
            String product_name = request.getParameter("product_name");
            String product_price = request.getParameter("product_price");

            ResultSet resultset = 

                    statement.executeQuery("select * from customer where first_name = '" + first_name + "'") ;
            statement.executeQuery("select * from customer where last_name = '" + last_name + "'") ; 



                statement.executeQuery("select * from customer_order where amount = '" + amount + "'") ;
            statement.executeQuery("select * from customer_order where date_created = '" + date_created + "'") ; 

            statement.executeQuery("select * from customer_order where reference_number = '" + reference_number + "'") ; 
            statement.executeQuery("select * from customer_order where invoice_number = '" + invoice_number + "'") ; 
            statement.executeQuery("select * from customer_order where status = '" + status + "'") ; 
            statement.executeQuery("select * from ordered_product where quantity = '" + quantity + "'") ; 
statement.executeQuery("select * from ordered_product where product_name = '" + product_name + "'") ;
statement.executeQuery("select * from ordered_product where product_price = '" + product_price + "'") ;

            if(!resultset.next()) {
                out.println("Sorry, could not find that order. ");
            } else {
        %>

        <div class="banner">   
       <% 
           } 
       %>
            </div>

        Invoice Number: <%= resultset.getString("invoice_number") %>
        Reference Number: <%= resultset.getString("reference_number") %>
        Created by: <%= resultset.getString("first_name") %> <%= resultset.getString("last_name") %>
        Date Created: <%= resultset.getString("date_created") %>
        Grand Total: <%= resultset.getString("amount") %>


        Order:
        <TABLE BORDER="1">
            <TR>
               <TH>Product Name</TH>
               <TH>Product Price</TH>
               <TH>Quantity</TH>
           </TR>
           <TR>
               <TD> <%= resultset.getString("product_name") %> </TD>
               <TD> <%= resultset.getString("product_price") %> </TD>
               <TD> <%= resultset.getString("quantity") %> </TD>
           </TR>
       </TABLE>
    </BODY>
</HTML>

Answer 1

部分之后

if(!resultset.next()) {
            out.println("Sorry, could not find that order. ");
        } else {
    %>

    <div class="banner">   
   <% 
       }

你离开了ResultSet。最后的} 放错了地方。关闭桌子后需要去。

修改

也许不是最好的方式，但它会起作用。为每个语句和查询引入更多ResultSet。然后在需要的地方使用它们。

示例：

Statement s1 = connection.createStatement(); Statement s2 = connection.createStatement(); Statement s3 = connection.createStatement(); Statement s4 = connection.createStatement(); ... ResultSet rs1 = s1.exequteQuery(.....); ResultSet rs2 = s2.exequteQuery(.....); ResultSet rs3 = s3.exequteQuery(.....); .......

然后在需要它们的地方使用rs1 .... rsN。工作解决方案：）

Answer 2

请注意Statement documentation说：

默认情况下，每个Statement对象只能同时打开一个ResultSet对象。

现在，您的程序中包含以下语句：

ResultSet resultset = 

        statement.executeQuery("select * from customer where first_name = '" + first_name + "'") ;
        statement.executeQuery("select * from customer where last_name = '" + last_name + "'") ; 

        statement.executeQuery("select * from customer_order where amount = '" + amount + "'") ;
        statement.executeQuery("select * from customer_order where date_created = '" + date_created + "'") ; 

        statement.executeQuery("select * from customer_order where reference_number = '" + reference_number + "'") ; 
        statement.executeQuery("select * from customer_order where invoice_number = '" + invoice_number + "'") ; 
        statement.executeQuery("select * from customer_order where status = '" + status + "'") ; 
        statement.executeQuery("select * from ordered_product where quantity = '" + quantity + "'") ; 
        statement.executeQuery("select * from ordered_product where product_name = '" + product_name + "'") ;
        statement.executeQuery("select * from ordered_product where product_price = '" + product_price + "'") ;

这意味着您使用相同的executeQuery对象多次调用Statement。但您只是将第一次执行的结果保存到resultset。

也就是说，ResultSet引用的resultset对象是此声明中的对象：

statement.executeQuery("select * from customer where first_name = '" + first_name + "'") ;

跟随它的所有其他查询都是单独的查询，如果您认为自己在做什么，则不会存储在同一个变量中。他们只是创建ResultSet对象，然后它被抛弃，因为你没有将结果分配给任何变量。

只要您调用第二个executeQuery，因为只允许一个ResultSet对象，ResultSet中存储的resultset对象将被关闭，而新的resultset.next()对象将被关闭打开。然后是另一个，然后是另一个。

无论如何，在您完成所有这些陈述后，您将进入检查ResultSet的部分。但在这一点上，正如我所说，那个对象已经被关闭了。

基本上，您应该决定要运行哪些查询，仅运行该特定查询，然后您在{{{{}}中有一个实时，开放的resultset 1}}。然后你可以填写它。

此外，从结果集中打印值的部分应位于else块内。您将它们放在else的大括号之后，这意味着当查询中没有返回任何行时您会遇到麻烦，因为您无论如何都要尝试打印它们。

Answer 3

以下代码有效（暗示您使用的是servlet）：

Form.jsp

 <form method="post" action="viewPublishers">
            Please enter the publisher ID you wish to view:
            <BR><br>
            <input type='text' name='pub_id' required>
            <BR><BR>
            <input type='submit' value="View">

        </form>

的response.jsp

    <% 
                Connection connection = DriverManager.getConnection("jdbc:mysql://localhost/app?user=root&password=12345");

                Statement statement = connection.createStatement();

                String pub_id = request.getParameter("pub_id);  

                ResultSet resultset = 
                    statement.executeQuery("select * from publishers where id = '" + pub_id+ "'") ; 

                if(!resultset.next()) {
                    out.println("Sorry, could not find that publisher.Please enter a valid ID. <a href='viewPublishers'>Try Again.</a> ");
                } else {
            %>




  <table>
              <thead>
  <tr>
    <th>Publisher ID</th>
    <th>First Name</th>
    <th>Last Name</th>
    <th>Books</th>
</thead>


<tbody style="font-size:small;">
  <tr>
    <td data-label="Publiser ID"><%= resultset.getString("pub_id") %></td>
    <td data-label="First Name"><%= resultset.getString("first_name") %></td>
    <td data-label="Last Name"><%= resultset.getString("last_name") %></td>
    <td data-label="Books"><%= resultset.getString("books") %>

 </tr>
                </tbody>
</table>

<div>   <% 
           } 
       %></div>

获取java.sql.SQLException：在尝试多个查询时，ResultSet关闭ERROR后不允许操作

3 个答案: