public List findCatalog() {
Query query = getEntityManager().createQuery("SELECT pc.productCatalog, p.name, p.product FROM ProductCatalog pc JOIN pc.products p");
return query.getResultList();
}
您好,通过这样的查询,我的应用程序可以正常编译。但是当我打开执行此查询的页面时,出现以下错误:
org.apache.jasper.JasperException: java.lang.NumberFormatException: For input string: "productCatalog"
productCatalog 是我的主键,但当我只包含名称列时也会发生同样的情况
exception org.apache.jasper.JasperException: java.lang.NumberFormatException: For input string: "name" root cause
java.lang.NumberFormatException: For input string: "name"
如果我不在我的查询中进行连接,那么可以打印 1 个表的结果。 我现在不知道问题出在哪里,我已经阅读了 Pro JPA 2 书,官方 Java EE 6 教程,用谷歌搜索了很多。 表设计是 ManyToMany。我有 product 表、*product_catalog* 表和绑定(bind)表 *product_product_catalog。我在绑定(bind)表中没有外键。 我已经使用 NetBeans EclipseLink 向导创建了实体类和外观类。
这是我如何在我的 ProductCatalog 类上映射多对多关系
@ManyToMany
@JoinTable(name = "product_product_catalog",
joinColumns = {
@JoinColumn(name = "product_catalog")
},
inverseJoinColumns = {
@JoinColumn(name = "product")
})
private Collection<Product> products;
product 和product_catalog 是对应表的主键。 现在我不知道我哪里错了,也许是映射错误?虽然我见过的许多例子都有相同的映射实现,但在他们的表中他们有外键,这会是一个问题吗? 此外,正如我所说,如果我不加入第二张 table ,一切都会正常进行。
这是我的 servlet,初始化该方法 getServletContext().setAttribute("productCatalog", productCatalogFacade.findCatalog());
这是我的 JSP 页面片段
<table>
<c:forEach var="list" items="${productCatalog}" varStatus="iter">
<tr>
<td>${list.productCatalog}</td>
<td>${list.product}</td>
<td>${list.name}</td>
</tr>
</c:forEach>
</table>
这是我想要实现的原生 SQL 查询
SELECT PPC.product_product_catalog, PPC.product_catalog, PPC.product, P.name, PC.name AS "catalog name", P.code, P.description, P.price, P.producer
FROM product_catalog PC
INNER JOIN product_product_catalog PPC ON PC.product_catalog = PPC.product_catalog
INNER JOIN product P ON P.product = PPC.product
因为我这里的最后一段代码是当我转到执行查询的页面时 glassfish 产生的输出:
WARNING: StandardWrapperValve[jsp]: PWC1406: Servlet.service() for servlet jsp threw exception
java.lang.NumberFormatException: For input string: "productCatalog"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at javax.el.ArrayELResolver.toInteger(ArrayELResolver.java:375)
at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:195)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:175)
at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
at org.apache.jasper.runtime.PageContextImpl.evaluateExpression(PageContextImpl.java:1007)
at org.apache.jsp.index_jsp._jspx_meth_c_forEach_0(index_jsp.java from :206)
at org.apache.jsp.index_jsp._jspService(index_jsp.java from :137)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:109)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:406)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:483)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:373)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1523)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:188)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:641)
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:97)
at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:85)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:185)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:325)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:226)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:165)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:791)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:693)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:954)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:170)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:135)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:102)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:88)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:76)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:53)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:57)
at com.sun.grizzly.ContextTask.run(ContextTask.java:69)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:330)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:309)
at java.lang.Thread.run(Thread.java:619)
最佳答案
当你在 SELECT
子句中执行带有许多变量的请求时,例如
SELECT pc.productCatalog, p.name, p.product ...
结果的每一行以Object[]
的形式返回,因此您需要使用数字索引来访问其元素:
<c:forEach var="list" items="${productCatalog}" varStatus="iter"><tr>
<td>${list[0]}</td>
<td>${list[2]}</td>
<td>${list[1]}</td>
</tr></c:forEach>
关于java.lang.NumberFormatException 尝试从查询中呈现值后,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5111369/