org.apache.jasper.runtime

Class TldScanner

java.lang.Object

org.apache.jasper.runtime.TldScanner

All Implemented Interfaces:

javax.servlet.ServletContainerInitializer

public class TldScanner
extends java.lang.Object
implements javax.servlet.ServletContainerInitializer

A container for all tag libraries that are defined "globally" for the web application. Tag Libraries can be defined globally in one of two ways: 1. Via elements in web.xml: the uri and location of the tag-library are specified in the element. 2. Via packaged jar files that contain .tld files within the META-INF directory, or some subdirectory of it. The taglib is 'global' if it has the element defined. A mapping between the taglib URI and its associated TaglibraryInfoImpl is maintained in this container. Actually, that's what we'd like to do. However, because of the way the classes TagLibraryInfo and TagInfo have been defined, it is not currently possible to share an instance of TagLibraryInfo across page invocations. A bug has been submitted to the spec lead. In the mean time, all we do is save the 'location' where the TLD associated with a taglib URI can be found. When a JSP page has a taglib directive, the mappings in this container are first searched (see method getLocation()). If a mapping is found, then the location of the TLD is returned. If no mapping is found, then the uri specified in the taglib directive is to be interpreted as the location for the TLD of this tag library.

Field Summary

Fields

Modifier and Type	Field and Description
static int	ABS_URI The types of URI one may specify for a tag library
static int	NOROOT_REL_URI
static int	ROOT_REL_URI

Constructor Summary

Constructors

Constructor and Description
TldScanner() Default Constructor.
TldScanner(javax.servlet.ServletContext ctxt, boolean isValidationEnabled) Constructor used in Jasper

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String[]	getLocation(java.lang.String uri) Gets the 'location' of the TLD associated with the given taglib 'uri'.
void	onStartup(java.util.Set<java.lang.Class<?>> c, javax.servlet.ServletContext ctxt)
static int	uriType(java.lang.String uri) Returns the type of a URI: ABS_URI ROOT_REL_URI NOROOT_REL_URI

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ABS_URI

public static final int ABS_URI

The types of URI one may specify for a tag library

See Also:

Constant Field Values

ROOT_REL_URI

public static final int ROOT_REL_URI

See Also:

Constant Field Values

NOROOT_REL_URI

public static final int NOROOT_REL_URI

See Also:

Constant Field Values

Constructor Detail

TldScanner

public TldScanner()

Default Constructor. This is only used for implementing ServletContainerInitializer. ServletContext will be supplied in the method onStartUp;

TldScanner

public TldScanner(javax.servlet.ServletContext ctxt,
          boolean isValidationEnabled)

Constructor used in Jasper

Method Detail

onStartup

public void onStartup(java.util.Set<java.lang.Class<?>> c,
             javax.servlet.ServletContext ctxt)
               throws javax.servlet.ServletException

Specified by:

onStartup in interface javax.servlet.ServletContainerInitializer

Throws:

javax.servlet.ServletException

getLocation

public java.lang.String[] getLocation(java.lang.String uri)
                               throws org.apache.jasper.JasperException

Gets the 'location' of the TLD associated with the given taglib 'uri'. Returns null if the uri is not associated with any tag library 'exposed' in the web application. A tag library is 'exposed' either explicitly in web.xml or implicitly via the uri tag in the TLD of a taglib deployed in a jar file (WEB-INF/lib).

Parameters:

uri - The taglib uri

Returns:

An array of two Strings: The first element denotes the real path to the TLD. If the path to the TLD points to a jar file, then the second element denotes the name of the TLD entry in the jar file. Returns null if the uri is not associated with any tag library 'exposed' in the web application. This method may be called when the scanning is in one of states: 1. Called from jspc script, then a full tld scan is required. 2. The is the first call after servlet initialization, then system jars that are knwon to have tlds but not listeners need to be scanned. 3. Sebsequent calls, no need to scans.

Throws:

org.apache.jasper.JasperException

uriType

public static int uriType(java.lang.String uri)

Returns the type of a URI: ABS_URI ROOT_REL_URI NOROOT_REL_URI