org.hd.d.pg2k.webSvr.catalogue
Class TreeFilterServletBase

java.lang.Object
  javax.servlet.GenericServlet
      javax.servlet.http.HttpServlet
          org.hd.d.pg2k.webSvr.catalogue.TreeFilterServletBase

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

Direct Known Subclasses:

TreeFilterServletAllExhibits, TreeFilterServletAllIcons

public abstract class TreeFilterServletBase
extends javax.servlet.http.HttpServlet

Servlet to do filtering and selection of one tree of exhibits for display. Sub-classes must implement getTitleCommonCatalogueName() and getFilter().

See Also:

Serialized Form

tfb

private final TreeFilterBean tfb

Bean that holds cache of selected data in tree-form for us. Only created at init().

TreeFilterServletBase

public TreeFilterServletBase()

doGet

protected void doGet(javax.servlet.http.HttpServletRequest request,
                     javax.servlet.http.HttpServletResponse response)
              throws javax.servlet.ServletException,
                     java.io.IOException

Handle a GET request. Ultimately we will internally redirect to the tree-display JSP, unless:

• There is an error, eg the request URI is malformed or impossible.
• We canonicalise the request with a redirection.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

java.io.IOException

redirectIfCanonicalisationNeeded

public static boolean redirectIfCanonicalisationNeeded(TreeFilterBean tfb,
                                                       javax.servlet.http.HttpServletResponse response,
                                                       java.lang.String baseURI,
                                                       java.lang.CharSequence wsPrefix,
                                                       javax.servlet.ServletContext context,
                                                       java.util.List<java.lang.CharSequence> nodeContent)
                                                throws java.io.IOException,
                                                       java.lang.IllegalStateException

302 TEMP REDIRECTS FOR NODES THAT CURRENTLY DUPLICATE THEIR PARENT NODE.

Returns:

true if a redirect has been done, so the caller should return immediately and not try to generate any page content.

Throws:

java.io.IOException

java.lang.IllegalStateException

destroy

public void destroy()

This clears the cache in the filter bean. We chain to super.destroy() to tidy up the underlying generic servlet.

Specified by:

destroy in interface javax.servlet.Servlet

Overrides:

destroy in class javax.servlet.GenericServlet

init

public void init()
          throws javax.servlet.ServletException

Initialises the servlet the filter bean. Derived class can choose to override it but should chain to it if so.

This sets the memory sensitivity and the filter expression.

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

getFilter

protected abstract Expr getFilter()

Get the filter expression to apply. Override in derived classes.

getTitleCommonCatalogueName

protected abstract java.lang.String getTitleCommonCatalogueName()

Get (short) title text common catalogue name; null if none. The expanded text should be 7-bit printable ASCII, possibly with embedded entities and mark-up.

Override in derived classes.

getDescriptionCommonCatalogueName

protected java.lang.String getDescriptionCommonCatalogueName()

Get descriptive text (i18n-ed if possible); null if none. The expanded text should be 7-bit printable ASCII, possibly with embedded entities and mark-up.

Defaults to null (no descriptive text).

Override as needed in derived classes.

getBreadcrumbs

protected Breadcrumbs getBreadcrumbs(LocaleBeanBase localeBean)

Get Breadcrumbs; null if none. By default, just a link to the top of the virtual collections, but can either be added to or replaced by an overriding class.

makeOfficialURI

public static java.lang.String makeOfficialURI(java.lang.CharSequence baseURI,
                                               java.lang.CharSequence prwseq)

Function to provide full "official" URI for page given base URI and word prefix. Note that the URI that this returns always ends with a slash to unambiguously mark the whole thing as a directory; no trailing "welcome" file component is added nor should be.

The suffix is also forced to lower-case to ensure canonicalisation.

Parameters:

baseURI - base URI for this tree; never null

prwseq - prefix word sequence, "" or lower-case word sequence ending in a hyphen.