org.apache.struts2.components
Class IteratorComponent

java.lang.Object
  extended by org.apache.struts2.components.Component
      extended by org.apache.struts2.components.ContextBean
          extended by org.apache.struts2.components.IteratorComponent

public class IteratorComponent
extends ContextBean

Iterator will iterate over a value. An iterable value can be any of: java.util.Collection, java.util.Iterator, java.util.Enumeration, java.util.Map, or an array.

The following example retrieves the value of the getDays() method of the current object on the value stack and uses it to iterate over. The <s:property/> tag prints out the current value of the iterator.

 
 <s:iterator value="days">
   <p>day is: <s:property/></p>
 </s:iterator>
 
 

The following example uses a Bean tag and places it into the ActionContext. The iterator tag will retrieve that object from the ActionContext and then calls its getDays() method as above. The status attribute is also used to create an IteratorStatus object, which in this example, its odd() method is used to alternate row colours:

 

 <s:bean name="org.apache.struts2.example.IteratorExample" var="it">
   <s:param name="day" value="'foo'"/>
   <s:param name="day" value="'bar'"/>
 </s:bean>
 

<table border="0" cellspacing="0" cellpadding="1"> <tr> <th>Days of the week</th> </tr>

<s:iterator value="#it.days" status="rowstatus"> <tr> <s:if test="#rowstatus.odd == true"> <td style="background: grey"><s:property/></td> </s:if> <s:else> <td><s:property/></td> </s:else> </tr> </s:iterator> </table>

The next example will further demonstrate the use of the status attribute, using a DAO obtained from the action class through OGNL, iterating over groups and their users (in a security context). The last() method indicates if the current object is the last available in the iteration, and if not, we need to separate the users using a comma:

 

  <s:iterator value="groupDao.groups" status="groupStatus">
      <tr class="<s:if test="#groupStatus.odd == true ">odd</s:if><s:else>even</s:else>">
          <td><s:property value="name" /></td>
          <td><s:property value="description" /></td>
          <td>
              <s:iterator value="users" status="userStatus">
                  <s:property value="fullName" /><s:if test="!#userStatus.last">,</s:if>
              </s:iterator>
          </td>
      </tr>
  </s:iterator>

 
 

The next example iterates over a an action collection and passes every iterator value to another action. The trick here lies in the use of the '[0]' operator. It takes the current iterator value and passes it on to the edit action. Using the '[0]' operator has the same effect as using <s:property />. (The latter, however, does not work from inside the param tag).

 

      <s:action name="entries" var="entries"/>
      <s:iterator value="#entries.entries" >
          <s:property value="name" />
          <s:property />
          <s:push value="...">
              <s:action name="edit" var="edit" >
                  <s:param name="entry" value="[0]" />
              </s:action>
          </push>
      </s:iterator>

 
 

A loop that iterates 5 times
 

 <s:iterator var="counter" begin="1" end="5" >
    <!-- current iteration value (1, ... 5) -->
    <s:property value="top" />
 </s:iterator>

 
 

Another way to create a simple loop, similar to JSTL's <c:forEach begin="..." end="..." ...> is to use some OGNL magic, which provides some under-the-covers magic to make 0-n loops trivial. This example also loops five times.
 

 <s:iterator status="stat" value="(5).{ #this }" >
    <s:property value="#stat.count" /> <!-- Note that "count" is 1-based, "index" is 0-based. -->
 </s:iterator>

 
 

A loop that iterates over a partial list
 

 <s:iterator value="{1,2,3,4,5}" begin="2" end="4" >
    <!-- current iteration value (2,3,4) -->
    <s:property value="top" />
 </s:iterator>

 
 


Nested Class Summary
(package private)  class IteratorComponent.CounterIterator
           
 
Field Summary
protected  Integer begin
           
protected  String beginStr
           
protected  Integer end
           
protected  String endStr
           
protected  Iterator iterator
           
private static Logger LOG
           
protected  Object oldStatus
           
protected  IteratorStatus status
           
protected  String statusAttr
           
protected  IteratorStatus.StatusState statusState
           
protected  Integer step
           
protected  String stepStr
           
protected  String value
           
 
Fields inherited from class org.apache.struts2.components.ContextBean
var
 
Fields inherited from class org.apache.struts2.components.Component
actionMapper, COMPONENT_STACK, parameters, stack, throwExceptionOnELFailure
 
Constructor Summary
IteratorComponent(ValueStack stack)
           
 
Method Summary
 boolean end(Writer writer, String body)
          Callback for the end tag of this component.
 void setBegin(String begin)
           
 void setEnd(String end)
           
 void setStatus(String status)
           
 void setStep(String step)
           
 void setValue(String value)
           
 boolean start(Writer writer)
          Callback for the start tag of this component.
 
Methods inherited from class org.apache.struts2.components.ContextBean
getVar, putInContext, setId, setVar
 
Methods inherited from class org.apache.struts2.components.Component
addAllParameters, addParameter, altSyntax, altSyntax, completeExpressionIfAltSyntax, copyParams, determineActionURL, determineNamespace, end, fieldError, findAncestor, findString, findString, findStringIfAltSyntax, findValue, findValue, findValue, getComponentStack, getParameters, getStack, popComponentStack, setActionMapper, setThrowExceptionsOnELFailure, stripExpressionIfAltSyntax, stripExpressionIfAltSyntax, toString, usesBody
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LOG

private static final Logger LOG

iterator

protected Iterator iterator

status

protected IteratorStatus status

oldStatus

protected Object oldStatus

statusState

protected IteratorStatus.StatusState statusState

statusAttr

protected String statusAttr

value

protected String value

beginStr

protected String beginStr

begin

protected Integer begin

endStr

protected String endStr

end

protected Integer end

stepStr

protected String stepStr

step

protected Integer step
Constructor Detail

IteratorComponent

public IteratorComponent(ValueStack stack)
Method Detail

start

public boolean start(Writer writer)
Description copied from class: Component
Callback for the start tag of this component. Should the body be evaluated?

Overrides:
start in class Component
Parameters:
writer - the output writer.
Returns:
true if the body should be evaluated

end

public boolean end(Writer writer,
                   String body)
Description copied from class: Component
Callback for the end tag of this component. Should the body be evaluated again?

NOTE: will pop component stack.

Overrides:
end in class Component
Parameters:
writer - the output writer.
body - the rendered body.
Returns:
true if the body should be evaluated again

setStatus

public void setStatus(String status)

setValue

public void setValue(String value)

setBegin

public void setBegin(String begin)

setEnd

public void setEnd(String end)

setStep

public void setStep(String step)


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