java.lang.Object
org.apache.struts.action.Action
org.apache.struts.actions.DispatchAction
org.apache.struts.actions.LookupDispatchAction(Struts1.1)
org.apache.struts.actions.EventDispatchAction(Struts1.2.9)
org.apache.struts.actions.MappingDispatchAction(Struts1.2)
DispatchAction
public abstract class DispatchAction extends Action
这是一个抽象的Action,它会根据request 中的parameter来执行相应的方法。通个这个Action类可以将不同的Action集中到一个Action文件中来。
struts-config.xml：
<action path="/subscription" type="org.example.SubscriptionAction" name="subscriptionForm" scope="request" input="/subscription.jsp" parameter="method"/>
在Action中要有相应的方法：
public class SubscriptionAction extends DispatchAction {
public ActionForward delete(ActionMapping mapping, ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception {}
public ActionForward insert(ActionMapping mapping, ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception {}
public ActionForward update(ActionMapping mapping, ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception {}
}
然后可以通过这样的方法来访问你的程序：
http://localhost:8080/myapp/subscription.do?method=delete
http://localhost:8080/myapp/subscription.do?method=insert
http://localhost:8080/myapp/subscription.do?method=update
如果parameter中参数为空，则调用Action中的unspecified方法
LookupDispatchAction
public abstract class LookupDispatchAction extends DispatchAction
通过这个Action抽象类继承DispatchAction，它的相应方法的执行由ActionMapping中parameter属性决定。每个动作实际上就是<html:submit>标签的property属性值。它适合在一个form中有很多按钮，按不同的按钮则执行不同的操作。
struts-config.xml：
<action path="/subscription" type="org.example.SubscriptionAction" name="subscriptionForm" scope="request"
input="/subscription.jsp" parameter="method"/>
ApplicationResources.properties：
button.add=Add Record
button.delete=Delete Record
JSP：
<%@ page pageEncoding="GBK"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<html>
<head>
<title>多提交演示</title>
</head>
<body>
<html:form action="subscription">
<html:submit property="method">
<bean:message key="button.add"/>
</html:submit>
<html:submit property="method">
<bean:message key="button.delete"/>
</html:submit>
</html:form>
</body>
</html>
在Action中必须实现getKeyMethodMap方法：
public class SubscriptionAction extends LookupDispatchAction {
protected Map getKeyMethodMap() {
Map map = new HashMap();
map.put("button.add", "add");
map.put("button.delete", "delete");
return map;
}
public ActionForward add(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception {}
public ActionForward delete(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception {}
}
EventDispatchAction
public class EventDispatchAction extends DispatchAction
通过这个Action抽象类继承DispatchAction，它的相应方法的执行由ActionMapping中parameter属性指定多个动作，中间用逗号(,)分隔。每个动作实际上就是<html:submit>标签的property属性值。它适合在一个form中有很多按钮，按不同的按钮则执行不同的操作。
struts-config.xml：
(parameter中的"recalc=recalculate"意思为<html:submit>标签的property属性值为recalc调用recalculate方法，出于安全考虑能够隐藏后台的业务方法名。"defaule=save"这是可选的，没有配置property属性的<html:submit>标签将调用defaule中设置的方法名，如果defaule没有指定任何参数，则调用Action中的unspecified方法)
<action path="/subscription" type="org.example.SubscriptionAction" name="subscriptionForm" scope="request"
input="/subscription.jsp" parameter="save,back,recalc=recalculate,default=save"/>
JSP：
<%@ page pageEncoding="GBK"%>
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<html>
<head>
<title>多提交演示</title>
</head>
<body>
<html:form action="subscription">
<html:submit property="save" value="保存"/>
<html:submit property="back" value="后退"/>
<html:submit property="recalc" value="重新计算"/>
</html:form>
</body>
</html>
责任编辑：小草
