struts2入门（5）--Struts2的拦截器
过滤器与拦截器的区别：*相同点：都是起拦截作用*不同点：
*作用范围：
*过滤器：使用范围是J2EE范畴，任何一个web工程都可以使用过滤器
*拦截器：使用范围是struts2范畴，离不开struts2框架的
*完成的功能：
*过滤器：拦截请求资源
*拦截器：完成其他所有功能
*执行顺序：
过滤器——>拦截器
常见的拦截器有哪些?
在哪里配置
struts-default.xml文件
package name=”struts-default”
<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="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" /> <!-- 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">dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</param> </interceptor-ref> <interceptor-ref name="conversionError"/> </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">dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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">dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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">dojo\..*,^struts\..*,^session\..*,^request\..*,^application\..*,^servlet(Request|Response)\..*,parameters\...*</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-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>
拦截器栈 就是拦截器的集合
默认使用的拦截器栈
<defaul-interceptor-ref name="defaultStack"/>
其中包含有以下的拦截器：
假设有一种场景：
在action的一个方法中，要进行权限的控制。如果是admin用户登入，就执行该方法，如果不是admin用户登入，就不能执行该方法。
判断用户是否存在的拦截器 ：
要自定义拦截器需要实现com.opensymphony.xwork2.interceptor.Interceptor接口：
public class PermissionInterceptor implements Interceptor {
private static final long serialVersionUID = -5178310397732210602L;
public void destroy() {
}
public void init() {
}
public String intercept(ActionInvocation invocation) throws Exception {
System.out.println("进入拦截器");
if(session里存在用户){
String result = invocation.invoke();
}else{
return “logon”;
}
//System.out.println("返回值:"+ result);
//return result;
}
}
说明：
<package name="csdn" namespace="/test" extends="struts-default">
<interceptors>
<interceptor name=“permission" class="cn.csdn.aop.PermissionInterceptor" />
<interceptor-stack name="permissionStack">
<interceptor-ref name="defaultStack" />
<interceptor-ref name=" permission " />
</interceptor-stack>
</interceptors>
<action name="helloworld_*" class="cn.csdn.action.HelloWorldAction" method="{1}">
<result name="success">/WEB-INF/page/hello.jsp</result>
<interceptor-ref name="permissionStack"/>
</action>
</package>
因为struts2中如文件上传，数据验证，封装请求参数到action等功能都是由系统默认的defaultStack中的拦截器实现的，所以我们定义的拦截器需要引用系统默认的defaultStack，这样应用才可以使用struts2框架提供的众多功能。
如果希望包下的所有action都使用自定义的拦截器，可以通过<default-interceptor-ref name=“permissionStack”/>把拦截器定义为默认拦截器。注意：每个包只能指定一个默认拦截器。另外，一旦我们为该包中的某个action显式指定了某个拦截器，则默认拦截器不会起作用。
