Struts2 之拦截器interceptor（3）

很多时候如果我们需要拦截指定的方法，前面的特性是完成不了的，引入了一个新的东西

1.拦截方法的拦截器

这时候我们要继承MethodFilterInterceptor这个类，它是支持方法过滤的

这个方法我们只需要实现doIntercept(ActionInvocation arg0)这个方法

看下原理

public String intercept(ActionInvocation invocation) throws Exception {
if (applyInterceptor(invocation)) {
return doIntercept(invocation);
}
return invocation.invoke();
}

我们可以看到interceptor是回调这个方法实现的，真正的拦截逻辑也在这里

protected boolean applyInterceptor(ActionInvocation invocation) {
String method = invocation.getProxy().getMethod();
// ValidationInterceptor
boolean applyMethod = MethodFilterInterceptorUtil.applyMethod(excludeMethods, includeMethods, method);
if (log.isDebugEnabled()) {
if (!applyMethod) {
log.debug("Skipping Interceptor... Method [" + method + "] found in exclude list.");
}
}
return applyMethod;
}

事实上excludeMethods和includeMethods都是Set集合，一个存储不拦截的方法--黑名单  一个则是白名单

黑白名单则是一般通过配置文件来指定的，不能手动指定，估计还是用的反射机制

public void setExcludeMethods(String excludeMethods) {
this.excludeMethods = TextParseUtil.commaDelimitedStringToSet(excludeMethods);
}

public void setIncludeMethods(String includeMethods) {
this.includeMethods = TextParseUtil.commaDelimitedStringToSet(includeMethods);
}

1.写Filter

package org.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;

public class MyFilterInterceptor extends MethodFilterInterceptor {

@Override
protected String doIntercept(ActionInvocation arg0) throws Exception {
// TODO Auto-generated method stub
this.setExcludeMethods("arg");
System.out.println("before");
String result=arg0.invoke();
if(arg0.isExecuted())
{
System.out.println("isexcuted");
}
System.out.println("after");
return result;
}

}

2.写Action

package org.actions;

import com.opensymphony.xwork2.ActionSupport;

public class TestAction extends ActionSupport {

public String arg()
{
return SUCCESS;
}

}

3.配置文件

<?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.ognl.allowStaticMethodAccess" value="true"></constant>
<constant name="struts.devMode" value="false" />
<constant name="struts.i18n.encoding" value="GBK"/>
<package name="actions" extends="struts-default" namespace="/actions">
<interceptors>
<interceptor name="myfilter" class="org.interceptor.MyFilterInterceptor">

</interceptor>
</interceptors>
<action name="user" class="org.actions.TestAction" method="arg">
<result >/success.jsp</result>

<interceptor-ref name="defaultStack"/>
<interceptor-ref name="myfilter">
<param name="excludeMethods">arg</param>
</interceptor-ref>
</action>
</package>
</struts>

 可以发现之前的效果输出没有了