在velocity使用toolbox.xml

首先必须在web.xml中添加：
<init-param>
<param-name>org.apache.velocity.toolbox</param-name>
<param-value>/WEB-INF/toolbox.xml</param-value>     
</init-param>
才可以使用toolbox.xml中定义的变量。

举例说明用法
比如我要使用日期，可以如下定义：
<toolbox>
<tool>
   <key>date</key>
   <scope>application</scope>
   <class>org.apache.velocity.tools.generic.DateTool</class>
   <parameter name="format" value="yyyy-M-d"/>
</tool>
</toolbox>
这里DateTool是velocity为我们预定义的工具类，还有很多其他工具类（比如：MathTool，ListTool，SortTool...）
date是这个类的实例，这样我们就可以在.vm中使用$date来引用DateTool中的方法了，如  $date.get('yyyy-M-d H:m:s')

如果我们要使用自己的类，只需要把org.apache.velocity.tools.generic.DateTool这部分替换成自己定义的类，然后再初始化该类的实例，比如<key>class</key>
在.vm中这样用$class.getXXX()

toolbox.xml典型配置：

<?xml version="1.0" encoding="UTF-8"?><!--=============================================================  @(#) toolbox.xml       Copyright (c) 2005, HOBOKEN Project, All Rights Reserved.=============================================================--><toolbox>    <!-- [ DateTool ]         @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/generic/DateTool.html  (ja)        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/DateTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>date</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.DateTool</class>    </tool>        <!-- [ MathTool ]        @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/generic/MathTool.html  (ja)        @see http://velocity.apache.org/tools/devel/generic/MathTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>math</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.MathTool</class>    </tool>        <!-- [ NumberTool ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/NumberTool.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>number</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.NumberTool</class>    </tool>        <!-- [ RenderTool ]        @see http://velocity.apache.org/tools/devel/generic/RenderTool.html  (en)        @since VelocityTools 1.0        <tool>        <key>render</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.RenderTool</class>    </tool>    -->        <!-- [ EscapeTool ]        @see http://velocity.apache.org/tools/devel/generic/EscapeTool.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>esc</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.EscapeTool</class>    </tool>        <!-- [ ResourceTool ]               @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/ResourceTool.html  (en)        @since Velocity 1.3    <tool>        <key>text</key>        <class>org.apache.velocity.tools.generic.ResourceTool</class>        <parameter name="bundles" value="resources,prj.hoboken.patrasche.resources.PatrascheResources" />        <parameter name="locale" value="ja_JP" />    </tool>    -->        <!-- [ AlternatorTool ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/AlternatorTool.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>alternator</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.AlternatorTool</class>    </tool>        <!-- [ ValueParser ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/ValueParser.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>parser</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.ValueParser</class>    </tool>        <!-- [ ListTool ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/ListTool.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>list</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.ListTool</class>    </tool>        <!-- [ SortTool ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/SortTool.html  (en)        @since VelocityTools 1.2    -->    <tool>        <key>sorter</key>        <scope>application</scope>        <class>org.apache.velocity.tools.generic.SortTool</class>    </tool>        <!-- [ IteratorTool ]        @see http://velocity.apache.org/tools/devel/javadoc/org/apache/velocity/tools/generic/IteratorTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>mill</key>        <scope>request</scope>        <class>org.apache.velocity.tools.generic.IteratorTool</class>    </tool>        <!--============================================================  [ TOOL FOR STRUTS TAGLIB ]============================================================-->    <!-- [ ActionMessagesTool ]        　        @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/ActionMessagesTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/ActionMessagesTool.html  (en)        @since VelocityTools 1.1    -->    <tool>        <key>messages</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.ActionMessagesTool</class>    </tool>        <!-- [ ErrorsTool ]        @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/ErrorsTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/ErrorsTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>errors</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.ErrorsTool</class>    </tool>        <!-- [ FormTool ]        @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/FormTool.html (ja)        @see http://velocity.apache.org/tools/devel/struts/FormTool.html (en)        @since VelocityTools 1.0    -->    <tool>        <key>form</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.FormTool</class>    </tool>        <!-- [ MessageTool ]         @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/MessageTool.html (ja)        @see http://velocity.apache.org/tools/devel/struts/MessageTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>resource</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.MessageTool</class>    </tool>        <!-- [ StrutsLinkTool ]        LinkTool                 @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/StrutsLinkTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/StrutsLinkTool.html  (en)        @since VelocityTools 1.0    -->    <tool>        <key>slink</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.StrutsLinkTool</class>    </tool>        <!-- [ SecureLinkTool ]        LinkTool                 @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/SecureLinkTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/SecureLinkTool.html  (en)        @since VelocityTools 1.1    -->    <tool>        <key>sslink</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.SecureLinkTool</class>    </tool>        <!-- [ TilesTool ]        Tiles                 @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/TilesTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/TilesTool.html  (en)        @since VelocityTools 1.1    -->    <tool>        <key>tiles</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.TilesTool</class>    </tool>        <!-- [ ValidatorTool ]        Validator                 @see http://www.jajakarta.org/velocity/tools/velocity-tools-1.1/docs-ja/struts/ValidatorTool.html  (ja)        @see http://velocity.apache.org/tools/devel/struts/ValidatorTool.html  (en)        @since VelocityTools 1.1    -->    <tool>        <key>validator</key>        <scope>request</scope>        <class>org.apache.velocity.tools.struts.ValidatorTool</class>    </tool>    <data type="string">        <scope>request</scope>        <key>app_version</key><value>3.0</value>    </data>    <data type="string">        <scope>request</scope>        <key>app_name</key><value>Patrasche</value>    </data>        <data type="string">        <scope>request</scope>        <key>next</key><value>/images/icon/next.jpg</value>    </data>    <data type="string">        <scope>request</scope>        <key>prev</key><value>/images/icon/prev.jpg</value>    </data>    <data type="string">        <scope>request</scope>        <key>top-page</key><value>/images/icon/top-page.jpg</value>    </data>    <data type="string">        <scope>request</scope>        <key>last-page</key><value>/images/icon/last-page.jpg</value>    </data>    <data type="string">        <scope>request</scope>        <key>pageIcon</key><value>/images/icon/page.png</value>    </data>    <data type="string">        <scope>request</scope>        <key>bookIcon</key><value>/images/icon/book.png</value>    </data>    <data type="string">        <scope>request</scope>        <key>defaultStyle</key><value>./web/default.css</value>    </data>    <data type="string">        <scope>request</scope>       <key>errorMetaHeader</key><value>/error/default_header.vm</value>    </data>    <data type="string">        <scope>request</scope>        <key>errorStyle</key><value>/error/error.css</value>    </data>    <data type="string">        <scope>request</scope>        <key>detailOfHTTP</key><value>./error/detail_HttpError.vm</value>    </data>    <data type="string">        <scope>request</scope>        <key>detailOfSERV</key><value>./error/detail_ServerError.vm</value>    </data>    <data type="string">        <scope>request</scope>        <key>multiPart</key><value>enctype='multipart/form-data'</value>    </data>    <data type="string">        <scope>request</scope>        <key>parentMark</key><value>..</value>    </data>    <data type="string">        <scope>request</scope>        <key>chartToolTips</key><value>toolTips</value>    </data>    <data type="string">        <scope>request</scope>        <key>chartClickable</key><value>isClickable</value>    </data>        <!-- [ NullTool ]    -->    <tool>        <key>null</key>        <scope>application</scope>        <class>com.company.util.velocity.NullTool</class>    </tool>    <!-- [ StringTool ]        文字操作            -->    <tool>        <key>words</key>        <scope>application</scope>        <class>com.company.util.velocity.StringTool</class>    </tool>        <!-- [ PageScrolllTool ]                    -->    <tool>        <key>pager</key>        <scope>session</scope>        <class>com.company.util.velocity.PageScrollTool</class>    </tool>    <!-- [ LoginUserTool ]    -->    <tool>        <key>loginuser</key>        <scope>request</scope>        <class>com.company.util.velocity.LoginUserTool</class>    </tool>    <!-- [ MenuTool ]    -->    <tool>        <key>menuviewer</key>        <scope>request</scope>        <class>com.company.util.velocity.MenuTool</class>    </tool>        <!-- [ FileSystemTool ]            -->    <tool>        <key>filesys</key>        <scope>request</scope>       <class>com.company.util.velocity.contrib.FileSystemTool</class>    </tool>        <!-- [ ExceptionTool ]                    -->    <tool>        <key>exception</key>        <scope>request</scope>        <class>com.company.util.velocity.ExceptionTool</class>    </tool>        <!-- [ POITool ]                      使用自己写的操作Excel的类    -->    <tool>        <key>poi</key>        <scope>request</scope>        <class>com.company.util.velocity.POITool</class>    </tool>    <!-- [ ConstantTool ]        使用自己定义的常量。    -->    <tool>        <key>constant</key>        <scope>application</scope>        <class>com.company.Constant</class>    </tool>    </toolbox>