java - 如何在jsp var中使用字符串？

Question

我想在 jsp 方面做这样的事情:

<c:forEach items="${configForm.unselectedServers}" var="item">
    String name = "";
    <c:forEach items="$item.configs" var="conf">
        name += ", " + {$conf.name}
        ....

有没有可能做这样的事情？

item.configs 它是一个类的数组(包含 name)。我知道那部分有效，我只是想知道如何将这些值放入字符串中。

---

编辑:

我收到以下错误:

Caused by: java.lang.NumberFormatException: For input string: ""
        at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
        at java.lang.Long.parseLong(Long.java:431)
        at java.lang.Long.<init>(Long.java:678)
        at org.apache.el.lang.ELArithmetic$LongDelegate.coerce(ELArithmetic.java:186)
        at org.apache.el.lang.ELArithmetic.coerce(ELArithmetic.java:357)
        at org.apache.el.lang.ELArithmetic.add(ELArithmetic.java:235)
        at org.apache.el.parser.AstPlus.getValue(AstPlus.java:40)
        at org.apache.el.parser.AstPlus.getValue(AstPlus.java:38)
        at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
        at org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:935)
        at org.apache.jsp.config.configDetail_jsp._jspx_meth_c_005fset_005f5(configDetail_jsp.java:509)
        at org.apache.jsp.config.configDetail_jsp._jspx_meth_c_005fforEach_005f1(configDetail_jsp.java:475)
        at org.apache.jsp.config.configDetail_jsp._jspx_meth_c_005fforEach_005f0(configDetail_jsp.java:407)
        at org.apache.jsp.config.configDetail_jsp.access$4(configDetail_jsp.java:384)
        at org.apache.jsp.config.configDetail_jsp$Helper.invoke1(configDetail_jsp.java:615)
        at org.apache.jsp.config.configDetail_jsp$Helper.invoke(configDetail_jsp.java:679)

Answer 1

怎么样:

<c:forEach items="${configForm.unselectedServers}" var="item">
  <c:set var="name" value="" />
  <c:forEach items="${item.configs}" var="conf">
    <c:set var="name" value="${name}, ${conf.name}" />
  </c:forEach>
</c:forEach>