struts-Constant Configuration

constant的搜索順序：

1. struts-default.xml
2. struts-plugin.xml
3. struts.xml
4. struts.properties
5. web.xml

constant有2個屬性：name和value

在 struts.properties中每一條記錄做爲constant

在web.xml 中能夠做爲一些file的參數初始化使用。

Constant Example (struts.xml)

<struts>

  <constant name="struts.devMode" value="true" />

  ... 

</struts>

Constant Example (struts.properties)

struts.devMode = true

Constant Example (web.xml)

<web-app id="WebApp_9" version="2.4" 
	xmlns="http://java.sun.com/xml/ns/j2ee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <filter>
        <filter-name>struts</filter-name>
        <filter-class>org.apache.struts2.dispatcher.FilterDispatcher</filter-class>
        <init-param>
        	<param-name>struts.devMode</param-name>
        	<param-value>true</param-value>
        </init-param>
    </filter>

    ...

</web-app>