在 JSF 数据表中显示 Hibernate/JPA 结果原因:java.lang.NumberFormatException:对于输入字符串:“[propertyname]"； [英] Showing Hibernate/JPA results in JSF datatable causes: java.lang.NumberFormatException: For input string: "[propertyname]"

问题描述

我最初使用以下查询来获取List:

I've initially the below query to obtain List<Employee>:

Query query = session.createQuery("select table1 from Table as table1");
this.employees = (List<Employee>) query.list();

这在下面的数据表中成功呈现:

This is successfully rendered in below datatable:

<p:dataTable var="employee" value="#{bean.employees}">
    <p:column id="name" headerText="Name">
        <h:outputText value="#{employee.name}" />
    </p:column>
    <p:column id="id" headerText="ID" >
        <h:outputText value="#{employee.id}" />
    </p:column>
</p:dataTable>

但是，当我尝试从以下 2 个表中检索它时:

However, when I try to retrieve it from 2 tables as below:

Query query = session.createQuery("select a.name, b.id from Table1 as a, Table2 as b"); 
this.employees = (List<Employee>) query.list();

它抛出以下异常:

java.lang.NumberFormatException: For input string: "name"
    at java.lang.NumberFormatException.forInputString(Unknown source)
    at java.lang.Integer.parseInt(Unknown source)
    at java.lang.Integer.parseInt(Unknown source)
    at javax.el.ArrayELResolver.toInteger(ArrayELResolver.java:166)
    at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46)
    ...

这是怎么引起的，我该如何解决?

How is this caused and how can I solve it?

推荐答案

您的 Hibernate 查询实际上返回的是 List，而不是 >列出<员工>，正如您在未经检查的演员期间错误地假设的那样.

Your Hibernate query is actually returning a List<Object[]>, not a List<Employee> as you incorrectly assumed during the unchecked cast.

证据在堆栈跟踪中:

java.lang.NumberFormatException: For input string: "name"
    at java.lang.NumberFormatException.forInputString(Unknown source)
    at java.lang.Integer.parseInt(Unknown source)
    at java.lang.Integer.parseInt(Unknown source)
    at javax.el.ArrayELResolver.toInteger(ArrayELResolver.java:166)
    at javax.el.ArrayELResolver.getValue(ArrayELResolver.java:46)
    ...

ArrayELResolver仅涉及name的基础(因此，#{employee})表示像 Object[] 这样的数组，而不是像 Bean 这样的 javabean.EL 正在尝试使用 name 通过索引获取数组项，对于第一项，它只能是一个整数，例如 #{employee[0]}.但是，字符串值 "name" 不能解析为整数，因此出现此异常.

The ArrayELResolver is only involved when the base of name (thus, the #{employee}) represents an array like Object[] not a javabean like Bean. EL is attempting to use the name to obtain the array item by index, which can only be an integer like so #{employee[0]} for the 1st item. However, the string value "name" is not parseable as an integer and hence this exception.

您有 2 个选项可以解决此问题:

You have 2 options to solve this problem:

• 更改 JSF 代码以期待 List.使用例如#{employee[0]}、#{employee[1]} 等

<p:dataTable var="employee" value="#{bean.employees}">
    <p:column id="name" headerText="Name">
        <h:outputText value="#{employee[0]}" />
    </p:column>
    <p:column id="id" headerText="ID" >
        <h:outputText value="#{employee[1]}" />
    </p:column>
</p:dataTable>

修复 Hibernate 查询以返回 real List.

• 输入字符串的NumberFormatException

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