Tip case -- else... If ....

Else... If...

<C: If test = ""> AAA </C: If> -- iftag. Java

<C: else> BBBB </C: else> -- elsetag. Java

Put in parent label

Let the IF and else object processors share a Boolean object to notify the respective label processors whether to execute the following code

<C: Choose> -- choosetag. Java

<C: whentest = "$ {user! = NULL} "> -- whentag. Java

This is my page

</C: When>

<C: Other> -- othertag. Java

If user is not ex

</C: Other>

</C: Choose>

Code:

Choosetag. Java

Private BooleanFlag =False;

// To read the flag value in the subclass, all get methods are required.

Public BooleanIsflag (){

ReturnFlag;

}

Public voidSetflag (BooleanFlag ){

This. Flag = flag;

}

@ Override

Public voidDotag ()ThrowsJspexception, ioexception {

//TodoAuto-generatedmethod stub

Jspfragment JF =This. Getjspbody ();

JF. Invoke (Null);

}

Otherwise. Java section:

Public voidDotag ()ThrowsJspexception, ioexception {

//TodoAuto-generatedmethod stub

// Obtain the parent tag object

Choosetag parent = (choosetag)This. Getparent ();

If(! Parent. isflag ()){

This. Getjspbody (). Invoke (Null);

Parent. setflag (True);

}

}

Whentag. Java

Private BooleanTest;

Public voidSettest (BooleanTest ){

This. Test = test;

}

@ Override

Public voidDotag ()ThrowsJspexception, ioexception {

//TodoAuto-generatedmethod stub

// Parent tag object

Choosetag parent = (choosetag)This. Getparent ();

If(Test &&! Parent. isflag () {// test is true, and no branch has been executed

// Process the TAG body

This. Getjspbody (). Invoke (Null);

Parent. setflag (True);

}

}

Testif. jsp

<% Session. setattribute ("user", "zhangsan"); %>

<Br/> __________________________________ <br/>

<! -- Test the IF and else labels -->

<C: Choose>

<C: When test ="$ {User! = NULL}">Aaaaa</C: When>

<C: otherwise>Bbbbbb</C: otherwise>

</C: Choose>

C. TLD Section

<? XML version ="1.0"Encoding =UTF-8"?>

<! Doctype taglib public "-// sunmicrosystems, Inc. // dtd jsp tag library 1.2 //" http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd ">

<Taglib>

<Tlib-version> 1.0 </tlib-version>

<JSP-version> 1.2 </JSP-version>

<Short-Name> C </short-Name>

<URI> http://www.c.com </uri>

<Tag>

<Name> If </Name>

<Tag-class> com. hbsi. Tag. iftag </Tag-class>

<Body-content>Scriptless</Body-content>

<Attribute>

<Name> test </Name>

<Required> true </required>

<Rtexprvalue> true </rtexprvalue>

</Attribute>

</Tag>

 

<Tag>

<Name> choose </Name>

<Tag-class> com. hbsi. Tag. choosetag </Tag-class>

<Body-content>Scriptless</Body-content>

</Tag>

 

<Tag>

<Name> when </Name>

<Tag-class> com. hbsi. Tag. whentag </Tag-class>

<Body-content>Scriptless</Body-content>

<Attribute>

<Name> test </Name>

<Required> true </required>

<Rtexprvalue> true </rtexprvalue>

</Attribute>

</Tag>

 

<Tag>

<Name> otherwise </Name>

<Tag-class> com. hbsi. Tag. otherwisetag </Tag-class>

<Body-content>Scriptless</Body-content>

</Tag>

</Taglib>