<package>元素可以把邏輯上相關的一組Action、Result、Intercepter等元素封裝起來，形成一個獨立的模塊，package可以繼承其他的package，也可以作為父包被其他的package繼承，比如“<package name="helloworld" extends="struts-default">”中，helloworld這個包就繼承了struts-default這個包。
<package>元素有如下屬性：
- name：包的名稱。必須配置
- extends：要繼承的包，后面配置的是被繼承的包的名稱。可選
- namespace：包的命名空間。可選
- abstract：定義包為抽象的，也就是不能包含Action的定義。可選
下面重點講解一下namespace和abstract屬性：
1）namespace屬性
namespace配置的是包的命名空間，同一個命名空間里面不能有同名的Action，當然不同的命名空間里面是可以有同名的Action的。類似於Java的包的功能，namespace可以有效的防止action重名的沖突，因為配置了namespace后，在訪問action的時候就需要添加namespace來作為action的前綴。如果不配置namespace，表示是默認的namespace，那么訪問的時候不需要添加namespace前綴。比如HelloWorld的示例，struts.xml的配置如下：
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"> <struts> <constant name="struts.devMode" value="true" /> <constant name="struts.locale" value="zh_CN"/> <constant name="struts.i18n.encoding" value="gb2312"/> <package name="helloworld" extends="struts-default"> <action name="helloworldAction" class="cn.javass.hello.struts2impl.action.HelloWorldAction"> <result name="toWelcome">/s2impl/welcome.jsp</result> </action> </package> </struts>
觀察里面<package>元素的定義，里面是沒有配置namespace的，因此在訪問的時候，是直接在webcontext下面寫要訪問的action的名稱的，示例如下：
<form action="/helloworld/helloworldAction.action" method="post"> …… </form>
其中“/helloworld”是webcontext。
如果配置了namespace，那么訪問的時候是必須要添加namespace前綴的，配置namespace的時候“/”表示namespace的根。示例如下：
……省略了 <package name="hello" namespace="/javass" extends="struts-default"> <action name="helloworldAction" class="cn.javass.hello.struts2impl.action.HelloWorldAction"> <result name="toWelcome">/s2impl/welcome.jsp</result> </action> </package>
那么訪問的時候就需要加上namespace，示例如下：
<form action="/helloworld/javass/helloworldAction.action" method="post"> …… </form>
2）abstract屬性
abstract用來定義包為抽象的，也就是不能包含Action的定義，但是抽象包可以被其他包繼承，因此里面可以定義其他包需要的元素，比如ResultType、Interceptor等等。
比如上面HelloWorld示例中繼承的struts-default包，它就是個抽象的包，定義示例如下：
<package name="struts-default" abstract="true"> <result-types> <result-type name="chain" class="com.opensymphony.xwork2.ActionChainResult"/> <result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/> <result-type name="freemarker" class="org.apache.struts2.views.freemarker.FreemarkerResult"/> <result-type name="httpheader" class="org.apache.struts2.dispatcher.HttpHeaderResult"/> <result-type name="redirect" class="org.apache.struts2.dispatcher.ServletRedirectResult"/> <result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/> <result-type name="stream" class="org.apache.struts2.dispatcher.StreamResult"/> <result-type name="velocity" class="org.apache.struts2.dispatcher.VelocityResult"/> <result-type name="xslt" class="org.apache.struts2.views.xslt.XSLTResult"/> <result-type name="plainText" class="org.apache.struts2.dispatcher.PlainTextResult" /> <result-type name="postback" class="org.apache.struts2.dispatcher.PostbackResult" /> </result-types> <interceptors> <interceptor name="alias" class="com.opensymphony.xwork2.interceptor.AliasInterceptor"/> <interceptor name="autowiring" class="com.opensymphony.xwork2.spring.interceptor.ActionAutowiringInterceptor"/> <interceptor name="chain" class="com.opensymphony.xwork2.interceptor.ChainingInterceptor"/> <interceptor name="conversionError" class="org.apache.struts2.interceptor.StrutsConversionErrorInterceptor"/> <interceptor name="cookie" class="org.apache.struts2.interceptor.CookieInterceptor"/> <interceptor name="cookieProvider" class="org.apache.struts2.interceptor.CookieProviderInterceptor"/> <interceptor name="clearSession" class="org.apache.struts2.interceptor.ClearSessionInterceptor" /> <interceptor name="createSession" class="org.apache.struts2.interceptor.CreateSessionInterceptor" /> <interceptor name="debugging" class="org.apache.struts2.interceptor.debugging.DebuggingInterceptor" /> <interceptor name="execAndWait" class="org.apache.struts2.interceptor.ExecuteAndWaitInterceptor"/> <interceptor name="exception" class="com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor"/> <interceptor name="fileUpload" class="org.apache.struts2.interceptor.FileUploadInterceptor"/> <interceptor name="i18n" class="com.opensymphony.xwork2.interceptor.I18nInterceptor"/> <interceptor name="logger" class="com.opensymphony.xwork2.interceptor.LoggingInterceptor"/> <interceptor name="modelDriven" class="com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor"/> <interceptor name="scopedModelDriven" class="com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor"/> <interceptor name="params" class="com.opensymphony.xwork2.interceptor.ParametersInterceptor"/> <interceptor name="actionMappingParams" class="org.apache.struts2.interceptor.ActionMappingParametersInteceptor"/> <interceptor name="prepare" class="com.opensymphony.xwork2.interceptor.PrepareInterceptor"/> <interceptor name="staticParams" class="com.opensymphony.xwork2.interceptor.StaticParametersInterceptor"/> <interceptor name="scope" class="org.apache.struts2.interceptor.ScopeInterceptor"/> <interceptor name="servletConfig" class="org.apache.struts2.interceptor.ServletConfigInterceptor"/> <interceptor name="timer" class="com.opensymphony.xwork2.interceptor.TimerInterceptor"/> <interceptor name="token" class="org.apache.struts2.interceptor.TokenInterceptor"/> <interceptor name="tokenSession" class="org.apache.struts2.interceptor.TokenSessionStoreInterceptor"/> <interceptor name="validation" class="org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor"/> <interceptor name="workflow" class="com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor"/> <interceptor name="store" class="org.apache.struts2.interceptor.MessageStoreInterceptor" /> <interceptor name="checkbox" class="org.apache.struts2.interceptor.CheckboxInterceptor" /> <interceptor name="profiling" class="org.apache.struts2.interceptor.ProfilingActivationInterceptor" /> <interceptor name="roles" class="org.apache.struts2.interceptor.RolesInterceptor" /> <interceptor name="annotationWorkflow" class="com.opensymphony.xwork2.interceptor.annotations.AnnotationWorkflowInterceptor" /> <interceptor name="multiselect" class="org.apache.struts2.interceptor.MultiselectInterceptor" /> <interceptor name="deprecation" class="org.apache.struts2.interceptor.DeprecationInterceptor" /> <!-- Basic stack --> <interceptor-stack name="basicStack"> <interceptor-ref name="exception"/> <interceptor-ref name="servletConfig"/> <interceptor-ref name="prepare"/> <interceptor-ref name="checkbox"/> <interceptor-ref name="multiselect"/> <interceptor-ref name="actionMappingParams"/> <interceptor-ref name="params"> <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*</param> </interceptor-ref> <interceptor-ref name="conversionError"/> <interceptor-ref name="deprecation"/> </interceptor-stack> <!-- Sample validation and workflow stack --> <interceptor-stack name="validationWorkflowStack"> <interceptor-ref name="basicStack"/> <interceptor-ref name="validation"/> <interceptor-ref name="workflow"/> </interceptor-stack> <!-- Sample file upload stack --> <interceptor-stack name="fileUploadStack"> <interceptor-ref name="fileUpload"/> <interceptor-ref name="basicStack"/> </interceptor-stack> <!-- Sample model-driven stack --> <interceptor-stack name="modelDrivenStack"> <interceptor-ref name="modelDriven"/> <interceptor-ref name="basicStack"/> </interceptor-stack> <!-- Sample action chaining stack --> <interceptor-stack name="chainStack"> <interceptor-ref name="chain"/> <interceptor-ref name="basicStack"/> </interceptor-stack> <!-- Sample i18n stack --> <interceptor-stack name="i18nStack"> <interceptor-ref name="i18n"/> <interceptor-ref name="basicStack"/> </interceptor-stack> <!-- An example of the paramsPrepareParams trick. This stack is exactly the same as the defaultStack, except that it includes one extra interceptor before the prepare interceptor: the params interceptor. This is useful for when you wish to apply parameters directly to an object that you wish to load externally (such as a DAO or database or service layer), but can't load that object until at least the ID parameter has been loaded. By loading the parameters twice, you can retrieve the object in the prepare() method, allowing the second params interceptor to apply the values on the object. --> <interceptor-stack name="paramsPrepareParamsStack"> <interceptor-ref name="exception"/> <interceptor-ref name="alias"/> <interceptor-ref name="i18n"/> <interceptor-ref name="checkbox"/> <interceptor-ref name="multiselect"/> <interceptor-ref name="params"> <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*</param> </interceptor-ref> <interceptor-ref name="servletConfig"/> <interceptor-ref name="prepare"/> <interceptor-ref name="chain"/> <interceptor-ref name="modelDriven"/> <interceptor-ref name="fileUpload"/> <interceptor-ref name="staticParams"/> <interceptor-ref name="actionMappingParams"/> <interceptor-ref name="params"> <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*</param> </interceptor-ref> <interceptor-ref name="conversionError"/> <interceptor-ref name="validation"> <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> <interceptor-ref name="workflow"> <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> </interceptor-stack> <!-- A complete stack with all the common interceptors in place. Generally, this stack should be the one you use, though it may do more than you need. Also, the ordering can be switched around (ex: if you wish to have your servlet-related objects applied before prepare() is called, you'd need to move servletConfig interceptor up. This stack also excludes from the normal validation and workflow the method names input, back, and cancel. These typically are associated with requests that should not be validated. --> <interceptor-stack name="defaultStack"> <interceptor-ref name="exception"/> <interceptor-ref name="alias"/> <interceptor-ref name="servletConfig"/> <interceptor-ref name="i18n"/> <interceptor-ref name="prepare"/> <interceptor-ref name="chain"/> <interceptor-ref name="scopedModelDriven"/> <interceptor-ref name="modelDriven"/> <interceptor-ref name="fileUpload"/> <interceptor-ref name="checkbox"/> <interceptor-ref name="multiselect"/> <interceptor-ref name="staticParams"/> <interceptor-ref name="actionMappingParams"/> <interceptor-ref name="params"> <param name="excludeParams">^class\..*,^dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,^parameters\..*,^action:.*,^method:.*</param> </interceptor-ref> <interceptor-ref name="conversionError"/> <interceptor-ref name="validation"> <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> <interceptor-ref name="workflow"> <param name="excludeMethods">input,back,cancel,browse</param> </interceptor-ref> <interceptor-ref name="debugging"/> <interceptor-ref name="deprecation"/> </interceptor-stack> <!-- The completeStack is here for backwards compatibility for applications that still refer to the defaultStack by the old name --> <interceptor-stack name="completeStack"> <interceptor-ref name="defaultStack"/> </interceptor-stack> <!-- Sample execute and wait stack. Note: execAndWait should always be the *last* interceptor. --> <interceptor-stack name="executeAndWaitStack"> <interceptor-ref name="execAndWait"> <param name="excludeMethods">input,back,cancel</param> </interceptor-ref> <interceptor-ref name="defaultStack"/> <interceptor-ref name="execAndWait"> <param name="excludeMethods">input,back,cancel</param> </interceptor-ref> </interceptor-stack> </interceptors> <default-interceptor-ref name="defaultStack"/> <default-class-ref class="com.opensymphony.xwork2.ActionSupport" /> </package>