LookupDispatchAction, MappingDispatchAction深入分析
首先我们来看一下它们三者之间的关系
java.lang.Object
|
+--org.apache.struts.action.Action
|
+--org.apache.struts.actions.DispatchAction
|
+--org.apache.struts.actions.LookupDispatchAction
|
+--org.apache.struts.actions.MappingDispatchAction
DispatchAction
定义
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="/saveSubscription" type="org.apache.struts.actions.DispatchAction" name="subscriptionForm" scope="request" input="/subscription.jsp" parameter="method"/>
在Action中要有相应的方法:
Public class demoAction 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
}
你就可以通过这样的方法来访问你的程序:
http://localhost:8080/myapp/saveSubscription.do?method=update
如果parameter中参数为空，则执行Action中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。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="/test"
type="org.example.MyAction"
name="MyForm"
scope="request"
input="/test.jsp"
parameter="method"/>
ApplicationResources.properties:
button.add=Add Record
button.delete=Delete Record
JSP:
<html:form action="/test">
<html:submit property="method">
<bean:message key="button.add"/>
</html:submit>
<html:submit property="method">
<bean:message key="button.delete"/>
</html:submit>
</html:form>
在Action 中必须实现getKeyMethodMap:
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 IOException, ServletException {
// do add
return mapping.findForward("success");
}
public ActionForward delete(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
// do delete
return mapping.findForward("success");
}
MappingDispatchAction
public class MappingDispatchAction extends DispatchAction
它的相应方法的执行由 ActionMapping中parameter名决定,注意这里和LookupDispatchAction不同，LookupDispatchAction的相应方法的执行由 ActionMapping中parameter属性决定，
struts-config.xml:
<action path="/saveSubscription"
type="org.example.SubscriptionAction"
name="subscriptionForm"
scope="request"
input="/subscription.jsp"
parameter="method"/>
Action:
public ActionForward create(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
public ActionForward edit(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
public ActionForward save(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
public ActionForward delete(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
public ActionForward list(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
for which you would create corresponding <action> configurations that reference this class:
<action path="/createSubscription"
type="org.example.SubscriptionAction"
parameter="create">
<forward name="success" path="/editSubscription.jsp"/>
</action>
<action path="/editSubscription"
type="org.example.SubscriptionAction"
parameter="edit">
<forward name="success" path="/editSubscription.jsp"/>
</action>
<action path="/saveSubscription"
type="org.example.SubscriptionAction"
parameter="save"
name="subscriptionForm"
validate="true"
input="/editSubscription.jsp"
scope="request">
<forward name="success" path="/savedSubscription.jsp"/>
</action>
<action path="/deleteSubscription"
type="org.example.SubscriptionAction"
name="subscriptionForm"
scope="request"
input="/subscription.jsp"
parameter="delete">
<forward name="success" path="/deletedSubscription.jsp"/>
</action>
<action path="/listSubscriptions"
type="org.example.SubscriptionAction"
parameter="list">
<forward name="success" path="/subscriptionList.jsp"/>
</action>