Struts logic tags are conditional tags that replaces scriptlets in the jsp files.
Struts logic tags are conditional tags that replaces scriptlets in the jsp files.Struts logic tags are conditional tags that replaces scriptlets in the jsp files.
Logic tags available in the Struts Framework
Tag Name | Description |
empty | If the requested variable is either null or an empty string then the nested body content of this tag is evaluated |
equal | If the requested variable is equal to the specified value then the nested body content of this tag is evaluated |
forward | It forwards the control to the page specified by the specified ActionForward entry. |
greaterEqual | If the value of the requested variable is greater than or equal to the specified value then the nested body content of this tag is evaluated |
greaterThan | If the value of the requested variable is greater than the specified value then the nested body content of this tag is evaluated |
iterate | It repeats the nested body content of this tag over a specified collection. |
lessEqual | If the value of the requested variable is less than or equal to the specified value then the nested body content of this tag is evaluated |
lessThan | If the value of the requested variable is less than the specified value then the nested body content of this tag is evaluated |
match | Evaluates the nested body content of this tag if the specified value is an appropriate substring of the requested variable. |
messagesNotPresent | If the specified message is not present in the request then it generates the nested body content of this tag . |
messagesPresent | If the specified message is present in this request then it generates the nested body content of this tag . |
notEmpty | If the requested variable is neither null nor an empty string nor an empty java.util.Collection (tested by the isEmpty() method on the java.util.Collection interface) then the nested body content of this tag is evaluated |
notEqual | If the requested variable is not equal to the specified value then the nested body content of this tag is evaluated |
notMatch | If the specified value is not an appropriate substring of the requested variable then the nested body content of this tag is evaluated |
notPresent | If the specified value is not present in the request then it generates the nested body content of this tag . |
present | If the specified value is present in the request then it generates the nested body content of this tag |
redirect | It renders an HTTP Redirect request. |
Struts logic tags uses equal, greaterEqual, greaterThan, lessEqual, lessThan, notEqual tags to compare the values. There are rules that must be followed :
double
or to a long
). Then a numeric (either floating point or
integer) type comparison is done. If numeric conversion fails than a String comparison
is performed.
cookie
, header
, name
, parameter
or property
available to the specified tag. This variable is
then converted to the
appropriate type needed for the comparison..
true
value then only the specific comparison is performed and subsequently the nested
body content is evaluated .Struts logic tags can also do the substring matching
using the tags (match
, notMatch
). There are
rules that must be followed :
cookie
, header
, name
, parameter
or property
available on this tag. Then this variable is converted to a String, if necessary.
location
attribute Location can be specified at the beginning (if location is set to start
), at
the end (if location is set to end
), or anywhere (if location
is not specified).A JspException
is thrown at runtime if any tag is utilized incorrectly or any invalid combination of tag
attributes are used. To
process the actual exception that caused the problem, a request attribute under key org.apache.struts.action.EXCEPTION
is passed to the error
page.
In the subsequent section we will show you the examples of these tags.
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