Class TldScanner

java.lang.Object
org.apache.jasper.runtime.TldScanner
All Implemented Interfaces:
javax.servlet.ServletContainerInitializer
public class TldScanner extends 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.
Author:
Pierre Delisle, Jan Luehe, Kin-man Chung servlet 3.0 JSP plugin, tld cache etc

  • Field Details

  • Constructor Details

    • 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 Details

    • onStartup

      public void onStartup(Set<Class<?>> c, javax.servlet.ServletContext ctxt) throws javax.servlet.ServletException
      Specified by:
      onStartup in interface javax.servlet.ServletContainerInitializer
      Throws:
      javax.servlet.ServletException

    • getLocation

      public String[] getLocation(String uri) throws 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:
      JasperException

    • uriType

      public static int uriType(String uri)
      Returns the type of a URI: ABS_URI ROOT_REL_URI NOROOT_REL_URI