" //Apache Software Foundation//DTD Tiles Configuration 1.1//EN"

       "http://jakarta.apache.org/struts/dtds/tiles config_1_1.dtd">

Discussion

With Tiles, you can base a Tile definition on the definition of another Tile. The new

definition, which extends the base definition, inherits the attributes of the base defi 

nition and overrides attributes as needed. When using Tiles, developers commonly

use the approach shown in the Solution. The

mainLayoutDef2

definition defines the

basic layout to be used across the application. In object oriented terms, you can

think of the base definition as an abstract class. The

.start

and

.pageOne

definitions

extend

mainLayoutDef2

. These definitions are like concrete subclasses of the abstract

base class.

The

.start

definition overrides two attributes:

title

and

body

. The overridden

title

specifies title text appropriate for the Start page. The

body

attribute in the base

mainLayoutDef2

does not specify a value; think of it as an abstract property. The

.start

definition overrides the

body

attribute by specifying a concrete value, a JSP page.

The

.pageOne

definition, which extends the

mainLayoutDef2

definition, overrides the

news

 attribute and sets the

title

 and

body

.

Extending Tile Definitions | 445

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