Class LDAPVirtualListControl

java.lang.Object
netscape.ldap.LDAPControl
netscape.ldap.controls.LDAPVirtualListControl
All Implemented Interfaces:
Serializable, Cloneable
Direct Known Subclasses:
LdapVirtualListControl
public class LDAPVirtualListControl extends LDAPControl
Represents control data for returning paged results from a search. Example of usage, with JFC: 
 // Call this to initialize the list box, whenever the search
 // conditions change.
 // "filter" may be "objectclass=person", for example
 void initListBox( String host, int port, String base, String filter ) {

 // Create list box if not already done
  if ( _dataList == null ) {
      _dataList = new JList();
      JScrollPane scrollPane = new JScrollPane(_dataList);
      add( scrollPane );
  }

  // Create a virtual data model
  vlistModel model = new vlistModel( host, port, base, filter );
  // Keep a buffer of one page before and one after
  model.setPageSize( getScrollVisibleSize() );
  _dataList.setModel( model );
 }

 // Data model to supply buffer list data
 class vlistModel extends AbstractListModel {
 vlistModel( String host, int port, String base, String filter ) {
     _base = base;
     _filter = filter;

     // Connect to the server
     try {
         _ldc = new LDAPConnection();
         System.out.println( "Connecting to " + host +
                             ":" + port );
         _ldc.connect( host, port );
     } catch ( LDAPException e ) {
         System.out.println( e );
         _ldc = null;
     }
 }

 // Called by JList to get virtual list size
   public int getSize() {
     if ( !_initialized ) {
         _initialized = true;
         _pageControls = new LDAPControl[2];
         // Paged results also require a sort control
         _pageControls[0] =
             new LDAPSortControl( new LDAPSortKey("cn"),
                                  true );
         // Do an initial search to get the virtual list size
         // Keep one page before and one page after the start
         _beforeCount = _pageSize;
         _afterCount = _pageSize;
         // Create the initial paged results control
         LDAPVirtualListControl cont =
             new LDAPVirtualListControl( "A",
                                         _beforeCount,
                                         _afterCount );
         _pageControls[1] = cont;
         _vlc = (LDAPVirtualListControl)_pageControls[1];
         getPage( 0 );
     }
     return _size;
 }

 // Get a page starting at first (although we may also fetch
 // some preceding entries)
 boolean getPage( int first ) {
     _vlc.setRange( first, _beforeCount, _afterCount );
     return getPage();
 }

 boolean getEntries() {
     // Specify necessary controls for vlv
     if ( _pageControls != null ) {
         try {
             _ldc.setOption( _ldc.SERVERCONTROLS, _pageControls );
         } catch ( LDAPException e ) {
             System.out.println( e + ", setting vlv control" );
         }
     }
     // Empty the buffer
     _entries.removeAllElements();
     // Do a search
     try {
         String[] attrs = { "cn" };
         LDAPSearchResults result =
             _ldc.search( _base,
                          LDAPConnection.SCOPE_SUB,
                          _filter,
                          attrs, false );
         while ( result.hasMoreElements() ) {
             LDAPEntry entry = (LDAPEntry)result.nextElement();
             LDAPAttribute attr = entry.getAttribute( attrs[0] );
             if ( attr != null ) {
                 Enumeration en = attr.getStringValues();
                 while( en.hasMoreElements() ) {
                     String name = (String)en.nextElement();
                     _entries.addElement( name );
                 }
             }
         }
     } catch ( LDAPException e ) {
         System.out.println( e + ", searching" );
         return false;
     }
     return true;
 }

 // Fetch a buffer
 boolean getPage() {
     // Get the actual entries
     if ( !getEntries() )
         return false;

     // Check if we have a control returned
     LDAPControl[] c = _ldc.getResponseControls();
     LDAPVirtualListResponse nextCont = null;
     for ( int i = 0; i < c.length; i++ ) {
         if ( c[i] instanceof LDAPVirtualListResponse ) {
             nextCont = (LDAPVirtualListResponse)c[i];
             break;
         }
     }
     if ( nextCont != null ) {
         _selectedIndex = nextCont.getFirstPosition() - 1;
         _top = Math.max( 0, _selectedIndex - _beforeCount );
         // Now we know the total size of the virtual list box
         _size = nextCont.getContentCount();
         _vlc.setListSize( _size );
     } else {
         System.out.println( "Null response control" );
     }
     return true;
 }

 // Called by JList to fetch data to paint a single list item
   public Object getElementAt(int index) {
     if ( (index < _top) || (index >= _top + _entries.size()) ) {
         getPage( index );
     }
     int offset = index - _top;
     if ( (offset < 0) || (offset >= _entries.size()) )
         return new String( "No entry at " + index );
     else
         return _entries.elementAt( offset );
 }

 // Called by application to find out the virutal selected index
   public int getSelectedIndex() {
     return _selectedIndex;
 }

 // Called by application to find out the top of the buffer
   public int getFirstIndex() {
     return _top;
 }

 public void setPageSize( int size ) {
     _pageSize = size;
 }

 Vector _entries = new Vector();
 protected boolean _initialized = false;
 private int _top = 0;
 protected int _beforeCount;
 protected int _afterCount;
 private int _pageSize = 10;
 private int _selectedIndex = 0;
 protected LDAPControl[] _pageControls = null;
 protected LDAPVirtualListControl _vlc = null;
 protected int _size = -1;
 private String _base;
 private String _filter;
 private LDAPConnection _ldc;
 }

  VirtualListViewRequest ::= SEQUENCE {
           beforeCount    INTEGER (0 .. maxInt),
           afterCount     INTEGER (0 .. maxInt),
           CHOICE {
               byIndex [0] SEQUENCE {
                   index           INTEGER,
                   contentCount    INTEGER
               }
               byFilter [1] jumpTo    Substring
           },
           contextID     OCTET STRING OPTIONAL
 }
Version:
1.0
See Also:

  • Field Details

    • VIRTUALLIST

      public static final String VIRTUALLIST
      See Also:

    • TAG_BYINDEX

      private static final int TAG_BYINDEX
      See Also:

    • TAG_BYFILTER

      private static final int TAG_BYFILTER
      See Also:

    • m_beforeCount

      private int m_beforeCount

    • m_afterCount

      private int m_afterCount

    • m_listIndex

      private int m_listIndex

    • m_listSize

      private int m_listSize

    • m_context

      private String m_context

  • Constructor Details

    • LDAPVirtualListControl

      LDAPVirtualListControl()
      Blank constructor for internal use in LDAPVirtualListControl.
      See Also:

    • LDAPVirtualListControl

      public LDAPVirtualListControl(String jumpTo, int beforeCount, int afterCount)
      Constructs a new LDAPVirtualListControl object. Use this constructor on an initial search operation, specifying the first entry to be matched, or the initial part of it.
      Parameters:
      jumpTo - an LDAP search expression defining the result set
      beforeCount - the number of results before the top/center to return per page
      afterCount - the number of results after the top/center to return per page
      See Also:

    • LDAPVirtualListControl

      public LDAPVirtualListControl(String jumpTo, int beforeCount, int afterCount, String context)

    • LDAPVirtualListControl

      public LDAPVirtualListControl(int startIndex, int beforeCount, int afterCount, int contentCount)
      Constructs a new LDAPVirtualListControl object. Use this constructor on a subsquent search operation, after we know the size of the virtual list, to fetch a subset.
      Parameters:
      startIndex - the index into the virtual list of an entry to return
      beforeCount - the number of results before the top/center to return per page
      afterCount - the number of results after the top/center to return per page
      See Also:

    • LDAPVirtualListControl

      public LDAPVirtualListControl(int startIndex, int beforeCount, int afterCount, int contentCount, String context)

  • Method Details

    • setRange

      public void setRange(int startIndex, int beforeCount, int afterCount)
      Sets the starting index, and the number of entries before and after to return. Apply this method to a control returned from a previous search, to specify what result range to return on the next search.
      Parameters:
      startIndex - the index into the virtual list of an entry to return
      beforeCount - the number of results before startIndex to return per page
      afterCount - the number of results after startIndex to return per page
      See Also:

    • setRange

      public void setRange(String jumpTo, int beforeCount, int afterCount)
      Sets the search expression, and the number of entries before and after to return.
      Parameters:
      jumpTo - an LDAP search expression defining the result set return.
      beforeCount - the number of results before startIndex to return per page
      afterCount - the number of results after startIndex to return per page
      See Also:

    • getIndex

      public int getIndex()
      Gets the size of the virtual result set.
      Returns:
      the size of the virtual result set, or -1 if not known.

    • getListSize

      public int getListSize()
      Gets the size of the virtual result set.
      Returns:
      the size of the virtual result set, or -1 if not known.

    • setListSize

      public void setListSize(int listSize)
      Sets the size of the virtual result set.
      Parameters:
      listSize - the virtual result set size

    • getBeforeCount

      public int getBeforeCount()
      Gets the number of results before the top/center to return per page.
      Returns:
      the number of results before the top/center to return per page.

    • getAfterCount

      public int getAfterCount()
      Gets the number of results after the top/center to return per page.
      Returns:
      the number of results after the top/center to return per page.

    • getContext

      public String getContext()
      Gets the optional context cookie.
      Returns:
      the optional context cookie.

    • setContext

      public void setContext(String context)
      Sets the optional context cookie.
      Parameters:
      context - the optional context cookie

    • createPageSpecification

      private byte[] createPageSpecification(String subFilter, int beforeCount, int afterCount)
      Creates a "flattened" BER encoding of the requested page specifications and return it as a byte array.
      Parameters:
      subFilter - filter expression for generating the results
      beforeCount - number of entries before first match to return
      afterCount - number of entries after first match to return
      Returns:
      the byte array of encoded data.

    • createPageSpecification

      private byte[] createPageSpecification(int listIndex, int listSize, int beforeCount, int afterCount)
      Creates a "flattened" BER encoding of the requested page specifications and return it as a byte array.
      Parameters:
      listIndex - the center or starting entry to return
      listSize - the virtual list size
      beforeCount - number of entries before the first match to return
      afterCount - number of entries after the first match to return
      Returns:
      the byte array of encoded data.

    • toString

      public String toString()
      Description copied from class: LDAPControl
      Return a string representation of the control for debugging
      Overrides:
      toString in class LDAPControl
      Returns:
      a string representation of the control.