带有f：setPropertyActionListener的JSF NumberFormatException [英] JSF NumberFormatException with f:setPropertyActionListener
问题描述
我使用f：setPropertyActionListener收到此错误，我无法弄清楚为什么：
I'm getting this error with f:setPropertyActionListener and i can't figure out why:
HTTP Status 500 - For input string: "selectedItem"
exception:
javax.servlet.ServletException: For input string: "selectedItem"
javax.faces.webapp.FacesServlet.service(FacesServlet.java:667)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause:
java.lang.NumberFormatException: For input string: "selectedItem"
java.lang.NumberFormatException.forInputString(Unknown Source)
java.lang.Integer.parseInt(Unknown Source)
java.lang.Integer.parseInt(Unknown Source)
javax.el.ListELResolver.coerce(ListELResolver.java:157)
javax.el.ListELResolver.getType(ListELResolver.java:50)
com.sun.faces.el.DemuxCompositeELResolver._getType(DemuxCompositeELResolver.java:215)
com.sun.faces.el.DemuxCompositeELResolver.getType(DemuxCompositeELResolver.java:242)
org.apache.el.parser.AstValue.getType(AstValue.java:60)
org.apache.el.ValueExpressionImpl.getType(ValueExpressionImpl.java:168)
com.sun.faces.facelets.el.TagValueExpression.getType(TagValueExpression.java:98)
com.sun.faces.facelets.tag.jsf.core.SetPropertyActionListenerHandler$SetPropertyListener.processAction(SetPropertyActionListenerHandler.java:209)
javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:813)
javax.faces.component.UICommand.broadcast(UICommand.java:300)
javax.faces.component.UIData.broadcast(UIData.java:1108)
javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:790)
javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1282)
com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:198)
javax.faces.webapp.FacesServlet.service(FacesServlet.java:654)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
表类：
// imports omitted
public class Table<E> extends ArrayList<E> {
private E selectedItem;
public E getSelectedItem() { return selectedItem; }
public void setSelectedItem(E value) { selectedItem = value; }
}
MyTable Bean：
MyTable Bean:
// Imports omitted
@ManagedBean
@ViewScoped
public class MyTable extends Table<File> {
@PostConstruct
public void initBean() {
// Loading some files into the list
}
}
这是XHTML：
<html> <!-- Namespaces and stuff omitted -->
<h:head>...</h:head>
<h:body>
<h:form>
<h:dataTable var="item" value="#{myTable}">
<h:column>
<h:commandButton value="Try Me!">
<f:setPropertyActionListener value="#{item}" target="#{myTable.selectedItem}"/>
<!-- I'm getting a warning from eclipse here: property not found -->
</h:commandButton>
</h:column>
</h:dataTable>
</h:form>
</h:body>
</html>
$ b ）。任何提示都被接受，谢谢！
I'm using Eclipse Luna (Java EE IDE) with Tomcat 8 and JSF 2.2.11 (mojarra). Any hints are accepted, thank you!
推荐答案
你用自己的花哨的实现将你的自我编码成一个角落。请查看的处理步骤 f：setActionPropertyListener 。您的代码在步骤3中阻塞：
You kind of coded your self into a corner with your fancy bean implementation. Take a look at the processing steps for the f:setActionPropertyListener. Your code is choking at step 3:
如果value表达式的值不为null，请调用getType（）值和目标ValueExpressions以确定其属性类型
If the value of the "value" expression is not null, call getType() on the "value" and "target" ValueExpressions to determine their property types
，原因如下：
-
EL处理器已经确定
myTable是一个列表。因此，它已将表达式myTable.selectedItem的评估委托给javax.el.ListELResolverclass
The EL processor has determined that
myTableis aList. Because of this, it has delegated the evaluation of the expressionmyTable.selectedItemto thejavax.el.ListELResolverclass
ELResolver在遇到 myTable 基础对象时，确定它是一个列表，并自动假定以下字符串是指一个列表索引，即myTable。 selectedItem ，其中 selectedItem 作为列表索引（根据EL规范， [] 和。可互换列表）。您可以在操作中看到它 here 。虽然在tomcat源中可能并不明显，但如果您在，您有以下注释：
The ELResolver, on encountering the myTable base object, determines it's a List and automatically assumes that the following string is referring to a list index, i.e. myTable.selectedItem, where selectedItem is supposed to be a list index (per the EL specification, the [] and . are interchangeable for lists). You can see it in action here. While it may not be immediately apparent in the tomcat source, if you check the comment in a similar implementation in Jboss for example, you have the following comment:
如果基础对象是列表，则返回值在给定的指数。 索引由属性参数指定，并强制为整数
property argument这里是指表达式的 selectedItem 部分
"property argument" here is referring to the selectedItem portion of your expression
- EL处理器现在尝试将字符串
selectedItem转换为一个整数（用作列表索引），这反过来会在一个500
- The EL processor now attempts to convert the string
selectedItemto an integer (to be used as a list index) which in turn explodes in a500
您将使您的工作变得更容易结合您的数据结构和支持bean，如Rami。 Q建议。更清洁的方式IMO
You'll make your work a whole lot easier by not combining your data structure and your backing bean, like Rami. Q suggested. Much cleaner that way IMO
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