如何在EL中使用静态方法? [英] How do I use static methods within EL?

问题描述

我正在使用jsp. bean.getConfigurationActionButtonBar()返回按钮对象的列表. WebUtils.getActionButtonBar(List buttonList)获取该列表并返回生成的html.很简单.

I'm working in a jsp. bean.getConfigurationActionButtonBar() returns a list of button objects. WebUtils.getActionButtonBar(List buttonList) takes that list and returns generated html. Very simple.

现在，由于某种原因，这不起作用:

Now, for some reason this doesn't work:

<td colspan="2">
    ${WebUtils.getActionButtonBar(bean.getConfigurationActionButtonBar())}
</td>

按钮列表已设置.调用静态WebUtils.getActionButtonBar时出了点问题.根本就不会打那个电话.有什么主意吗?

The button list is set. Something's wrong with the call to static WebUtils.getActionButtonBar. That call is simply never made. Any idea?

推荐答案

您需要将其声明为EL函数，并将其注册在单独的taglib中.

You need to declare it as an EL function and register it in a separate taglib.

首先创建一个/WEB-INF/functions.tld文件:

<?xml version="1.0" encoding="UTF-8" ?>
<taglib 
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
    version="2.1">

    <display-name>Custom Functions</display-name>    
    <tlib-version>1.0</tlib-version>
    <uri>http://example.com/util</uri>

    <function>
        <name>getActionButtonBar</name>
        <function-class>com.example.WebUtils</function-class>
        <function-signature>java.lang.String getActionButtonBar(java.util.List)</function-signature>
    </function>
</taglib>

然后您可以按以下方式使用它:

Then you can use it as follows:

<%@taglib uri="http://example.com/util" prefix="util" %>
...
${util:getActionButtonBar(bean.getConfigurationActionButtonBar())}

但是，您在实现具体功能要求方面走了完全错误的道路. HTML应该由JSP文件生成，而不是由原始Java代码生成.请改用JSP包含文件或标记文件.

However, you're going completely the wrong path as to achieving the concrete functional requirement. HTML should be generated by JSP files, not by raw Java code. Use a JSP include file or tag file instead.

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