Struts2拦截器的基本用法

方法一：
继承抽象截器(AbstractInterceptor)
拦截器Java代码：

package action;

import java.util.Map;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class AuthInterceptor extends AbstractInterceptor {
	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		ActionContext ctx = ActionContext.getContext();
		Map session = ctx.getSession();
		Object user = session.get("user");

		if (user == null) {
			ActionSupport action = (ActionSupport) invocation.getAction();
			action.addActionError("请先登录!");
			return Action.LOGIN;
		} else {
			return invocation.invoke();
		}
	}
}

Struts.xml文件：

...
<package name="Node" extends="struts-default" namespace="/Node">
	<interceptors>
		<!-- 定义AuthInterceptor拦截器 -->
		<interceptor name="auth" class="action.AuthInterceptor"/>
		<!-- 定义自己的拦截器栈，在Action的配置中，可以直接引用这个拦截器栈 -->
		<interceptor-stack name="securityStack">
			<interceptor-ref name="defaultStack"/>
			<interceptor-ref name="auth"/>
		</interceptor-stack>
	</interceptors>

	<!--<default-interceptor-ref name="securityStack"/>--> 

	<global-results>
		<result name="login">/login.jsp</result>
	</global-results>

	<action name="show" method="show" class="action.NodeAction">
		<result>show.jsp</result>
		<interceptor-ref name="securityStack"/>
	</action>

	...

</package>
...

在21行，如果直接用自己的拦截器<interceptor-ref name="authStack"/>，而不用拦截器栈时的话，默认拦截器的功能被取消了，有可能出错。
所以需要在<interceptor-ref name="authStack"/>后边加上<interceptor-ref name="defaultStack"/>这一句，再次显式的定义使用默认拦截器栈：

	<action name="show" method="show" class="action.NodeAction">
		<result>show.jsp</result>
		<interceptor-ref name="authStack"/>
		<interceptor-ref name="defaultStack"/>
	</action>

方法二：
继承方法过滤拦截器(MethodFilterInterceptor)
拦截器Java代码：

package action;

import java.util.Map;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;

public class AuthInterceptor extends MethodFilterInterceptor{
	@Override
	protected String doIntercept(ActionInvocation invocation) throws Exception {
		ActionContext ctx = ActionContext.getContext();
		Map session = ctx.getSession();
		Object user = session.get("user");

		if (user == null) {
			ActionSupport action = (ActionSupport) invocation.getAction();
			action.addActionError("请先登录!");
			return Action.LOGIN;
		} else {
			return invocation.invoke();
		}
	}
}

Struts.xml文件：

...
<package name="Node" extends="struts-default" namespace="/Node">
	<interceptors>
		<!-- 定义LoggerInterceptor拦截器 -->
		<interceptor name="logger" class="action.LoggerInterceptor">
			<param name="includeMethods"></param>
			<param name="excludeMethods"></param>
		</interceptor>
		<!-- 定义AuthInterceptor拦截器 -->
		<interceptor name="auth" class="action.AuthInterceptor">
			<param name="includeMethods">show,edit</param>
			<param name="excludeMethods">login</param>
		</interceptor>
		
		<!-- 定义自己的拦截器栈，在Action的配置中，可以直接引用这个拦截器栈 -->
		<interceptor-stack name="myStack">
			<interceptor-ref name="logger"/>
			<interceptor-ref name="auth"/>
			<interceptor-ref name="defaultStack"/>
		</interceptor-stack>
	</interceptors>
	
	<!-- 默认拦截器 -->
	<default-interceptor-ref name="myStack"/> 

	<global-results>
		<result name="login">/login.jsp</result>
	</global-results>

	<action name="show" method="show" class="action.NodeAction">
		<result>show.jsp</result>
		<!-- 自己的拦截器 -->
	</action>

	...

</package>
...

第26行，配置了默认的拦截器引用，这样在<action中就不用写<interceptor-ref了。
如果需要在<action中单独配置另外的拦截器xxxStack，可以在34行处加入：

<action name="show" method="show" class="action.NodeAction">
	<result>show.jsp</result>
	<interceptor-ref name="xxxStack"/>
	<interceptor-ref name="defaultStack"/>
</action>

引用

NOTE: If method name are available in both includeMethods and excludeMethods, it will still be considered as an included method. In short includeMethods takes precedence over excludeMethods.