Logic Match Tag (<logic:match >...</logic:match
>)
match tag - We use this tag to
evaluate the contents contained in the nested body parts of this tag if the
specified value is an appropriate substring of the requested variable.
This tag matches the variable specified as a String
against the specified constant value. If the value is a substring then the
nested body content of this tag is evaluated.
Attributes of match Tag
| Attribute Name |
Description |
| cookie |
The variable to be matched is the value of the
cookie whose name is specified by this attribute.
|
| header |
The variable to be matched is the value of the
header whose name is specified by this attribute. The name match is
performed in a case insensitive manner.
|
| location |
If not specified, a match between the variable
and the value may occur at any position within the variable string. If
specified, the match must occur at the specified location (either start
or end) of the variable string.
|
| name |
The variable to be matched is the JSP bean
specified by this attribute, if property is not specified,
or the value of the specified property of this bean, if property
is specified.
|
| parameter |
The variable to be matched is the first, or
only, value of the request parameter specified by this attribute.
|
| property |
The variable to be matched is the property (of
the bean specified by the name attribute) specified by this
attribute. The property reference can be simple, nested, and/or indexed.
|
| scope |
The bean scope within which to search for the
bean named by the name property, or "any scope"
if not specified.
|
| value |
The constant value which is checked for
existence as a substring of the specified variable.
|
Logic notMatch Tag (<logic:notMatch >...</logic:notMatch
>)
notMatch
- We use this tag to
evaluate the contents contained in the nested body parts of this tag if the
specified value is not a substring of the requested variable.
This tag matches
the variable specified by one of attributes (as a String) against the
specified constant value. If the value is not a substring the nested body
content of this tag is evaluated.
Attributes of notMatch Tag
| Attribute Name |
Description |
| cookie |
The variable to be matched is the value of the
cookie whose name is specified by this attribute.
|
| header |
The variable to be matched is the value of the
header whose name is specified by this attribute. The name match is
performed in a case insensitive manner.
|
| location |
If not specified, a match between the variable
and the value may occur at any position within the variable string. If
specified, the match must occur at the specified location (either start
or end) of the variable string.
|
| name |
The variable to be matched is the JSP bean
specified by this attribute, if property is not specified,
or the value of the specified property of this bean, if property
is specified.
|
| parameter |
The variable to be matched is the first, or
only, value of the request parameter specified by this attribute.
|
| property |
The variable to be matched is the property (of
the bean specified by the name attribute) specified by this
attribute. The property reference can be simple, nested, and/or indexed.
|
| scope |
The bean scope within which to search for the
bean named by the name property, or "any scope"
if not specified.
|
| value |
The constant value which is checked for
existence as a substring of the specified variable.
|
Example Illustrating the use of the Match <logic:match
>
and the notMatch <logic:notMatch > logic tags.
Here you will learn to use the Struts Logic tags.
We will cover an example that will show a comparison between the two
logic tags (ie..<logic:match > and the <logic:notMatch>).
Example code
Creating an Action
Class
Develop a simple action class LogicAction.java.
package roseindia.net;
import java.io.*;
import java.util.*;
/**
* @author Amit Gupta
* @Web http://www.roseindia.net
* @Email struts@roseindia.net
**/
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import org.apache.struts.action.*;
public class LogicAction extends Action
{
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
return mapping.findForward("success");
}
}
|
|
Creating Form Bean
Our form bean class contains only one property text.
Here is the code of FormBean (LogicForm.java)
package roseindia.net;
import org.apache.struts.action.*;
/**
* @author Amit Gupta
* @Web http://www.roseindia.net
* @Email struts@roseindia.net
**/
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class EmptyForm extends ActionForm
{
private String text = "";
public String getText()
{
return text;
}
public void setText(String text)
{
this.text=text;
}
}
|
|
Defining form Bean in struts-config.xml file
Add the following entry in the struts-config.xml file
for defining the form bean
<form-bean name="LogicForm"
type="roseindia.net.LogicForm" /> |
Developing the Action Mapping in the struts-config.xml
Here, Action mapping helps to select the method from the Action class for specific
requests.
<action path="/LogicAction"
type="roseindia.net.LogicAction"
name="LogicForm"
scope="request"
input="/pages/InputLogic.jsp">
<forward name="success" path="/pages/output.jsp"/>
</action> |
Developing the InputLogic.jsp
page
<%@ taglib uri="/tags/struts-html"
prefix="html" %>
<%@ taglib uri="/tags/struts-logic"
prefix="logic" %>
<html:html>
<head>
<title>Using <logic> Tags</title>
</head>
<body>
<h1>Using <logic> Tags</h1>
<html:form action="/LogicAction" method
="post">
<h2>Enter text:</h2>
<html:text property="text"/>
<br>
<h4>The <logic:match>tag works if the entered
</h4>
<h4>text contains "amit"</h4>
<h4>The <logic:notMatch>tag always evaluate the
</h4>
<h4>entered text against the"abc" value</h4>
<br>
<html:submit value="Submit"/>
<html:cancel/>
</html:form>
</body>
</html:html> |
Developing the output.jsp page
Notice the values
<%@ taglib uri="/tags/struts-bean"
prefix="bean" %>
<%@ taglib uri="/tags/struts-logic"
prefix="logic" %>
<HTML>
<HEAD>
<TITLE>Here's Your Data...</TITLE>
</HEAD>
<BODY>
<H4>Here's Your Data...</H4>
<h4>The text entered is:
<bean:write name="LogicForm"
property="text"/></h4>
<logic:match name="LogicForm" property="text"
value="amit">
<h5>Using the tag <logic:match > </h5>
Result : entered text contains "amit"
</logic:match>
<logic:notMatch name="LogicForm" property="text"
value="abc">
<h5>Using the tag<logic:notMatch></h5>
Result: entered text does not contains "abc"
</logic:notMatch>
</BODY>
</HTML> |
Add the following line in the index.jsp to call the
form.
<li>
<html:link page="/pages/InputLogic.jsp">Struts File Upload</html:link>
<br>
Example demonstrates how LogicAction Class works.
</li>
Building and Testing the Example
To build and deploy the application go to Struts\Strutstutorial
directory and type ant on the command prompt. This will deploy the application.
Open the browser and navigate to the InputLogic.jsp page. Your browser
displays the following page.
Writing text including "amit" and excluding
"abc" to the InputLogic.jsp page
displays the working of the match Logic tag <logic:match > and
the notMatch Logic tag <logic:notMatch > .
It displays the following to the out.jsp
page
Writing text including "amit" and
"abc" to the InputLogic.jsp page
displays the working of the match Logic tag <logic:match > and
the notMatch Logic tag <logic:notMatch > .
The <logic:notEqual
> evaluated here displays the output.jsp
as
|
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