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java.lang.Objectorg.apache.struts2.components.Component
org.apache.struts2.components.IteratorComponent
public class IteratorComponent
Iterator will iterate over a value. An iterable value can be either of: java.util.Collection, java.util.Iterator, java.util.Enumeration, java.util.Map, 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 a IteratorStatus
object, which in this example, its odd() method is used to alternate row
colours:
<s:bean name="org.apache.struts2.example.IteratorExample" id="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 seperate 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" id="entries"/> <s:iterator value="#entries.entries" > <s:property value="name" /> <s:property /> <s:push value="..."> <s:action name="edit" id="edit" > <s:param name="entry" value="[0]" /> </s:action> </push> </s:iterator>To simulate a simple loop with iterator tag, the following could be done. It does the loop 5 times.
<s:iterator status="stat" value="{1,2,3,4,5}" > <!-- grab the index (start with 0 ... ) --> <s:property value="#stat.index" /> <!-- grab the top of the stack which should be the --> <!-- current iteration value (0, 1, ... 5) --> <s:property value="top" /> </s:iterator>
Field Summary | |
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protected java.util.Iterator |
iterator
|
protected java.lang.Object |
oldStatus
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protected IteratorStatus |
status
|
protected java.lang.String |
statusAttr
|
protected IteratorStatus.StatusState |
statusState
|
protected java.lang.String |
value
|
Fields inherited from class org.apache.struts2.components.Component |
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COMPONENT_STACK, id, parameters, stack |
Constructor Summary | |
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IteratorComponent(com.opensymphony.xwork2.util.ValueStack stack)
|
Method Summary | |
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boolean |
end(java.io.Writer writer,
java.lang.String body)
Callback for the end tag of this component. |
void |
setStatus(java.lang.String status)
if specified, an instanceof IteratorStatus will be pushed into stack upon each iteration |
void |
setValue(java.lang.String value)
the iteratable source to iterate over, else an the object itself will be put into a newly created List |
boolean |
start(java.io.Writer writer)
Callback for the start tag of this component. |
Methods inherited from class org.apache.struts2.components.Component |
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addAllParameters, addParameter, altSyntax, copyParams, determineActionURL, determineNamespace, end, fieldError, findAncestor, findString, findString, findValue, findValue, findValue, getComponentStack, getId, getParameters, getStack, popComponentStack, setId, toString, usesBody |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
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protected java.util.Iterator iterator
protected IteratorStatus status
protected java.lang.Object oldStatus
protected IteratorStatus.StatusState statusState
protected java.lang.String statusAttr
protected java.lang.String value
Constructor Detail |
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public IteratorComponent(com.opensymphony.xwork2.util.ValueStack stack)
Method Detail |
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public boolean start(java.io.Writer writer)
Component
start
in class Component
writer
- the output writer.
public boolean end(java.io.Writer writer, java.lang.String body)
Component
end
in class Component
writer
- the output writer.body
- the rendered body.
public void setStatus(java.lang.String status)
public void setValue(java.lang.String value)
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