creating a tree in JSP

Hi,
I am a newbie in JSPs and would like to have some help with the following problem, I would like to create a tree structure in JSP, say for example depicting the directory structure in windows. The directory structure looks like this

Root
My Computer
C:
test.txt
data.dat
D:
test1.txt
faq.txt
ANOTHER_DIR
xxx1.text
YYY1.dat
My Documents
My Pictures

Under this structure each file if it is a directory,has more files. What would be the best manner in which to achieve this. Would it be to parse the directory structure using J2SE, write it to a XML document and to process this document using JSP or is there any other easier way.

Thanks

Vijai

Check Jenkov JSP Tree Tag and JSP Tree Tag.

thanks, but I would also like to know how to get the whole directory hierarchy across to the JSP, for example,

They must be having provision for it. Just check the documentation.

A couple of years ago I wrote a bean to facilitate presenting a file system tree in JSP and allowing the user to browse it and forward a selected directory/file to a servlet. Here is the bean code:

/**
* A class to support file system browsing via a JSP page
* @author William B. Brogden
* @version 1.0
*  6/04/04 start
*/
 
package com.wbprep.util ;
 
import java.io.* ; 
import java.util.* ;
 
public class FileSelectBean {
 
 /** restricts files shown to those with this type
 * @see use in  listFiles
 */
  static String fileSel = ".xml" ;
  
  File[] parentDirs ; // rebuilt with every call to setParentDirs
  File currentDir ; // as resulting from a call to setParentDirs
  File[] childDirs ; // see getChildDirs
  File[] childFiles ; // see getChildFiles
  
 /** The following variables MUST be set before setCurrentDir is called.
 * @see the index.jsp page 
 * @see the setSelectAlias etc methods
 */ 
  String selectAlias = "URL for this fileselect servlet";
  String actionAlias = "some URL for action servlet" ;
  String[] legalDirs ;
 
/** a no-args constructor is required for bean creation by the
* <jsp:useBean tag in index.jsp
*/  
  public FileSelectBean() {
    System.out.println("No-args constructor for FileSelectBean");
  }
 
/** A constructor that also initializes the current directory.
*  originally used for testing
*/
  public FileSelectBean( String s ) throws IOException {
    File f = new File( s );
    if( f.isFile() ){
      f = f.getParentFile();
      System.out.println("file " + s + " backed up to parent " + f );
    }
    setParentDirs( f );
  }
 
  
  public void setLegalRoots( String[] s ){ legalDirs = s ; }
  public void setSelectAlias( String s ){ selectAlias = s ; }
  public void setActionAlias( String s ){ actionAlias = s ; }
 
/** This method sets the current directory and parent directories
 *  either initial setting OR move to due to selection of option
 *  The String s is expected to be a directory, but it can cope with a file
 */
  public void setCurrentDir( String s ){
    File f = new File( s );
    if( f.isFile() ){
      f = f.getParentFile();
    }
    setParentDirs( f );
    System.out.println("currentDir set using" + s  );
  }
  
  public String getCurrentDir( ){ 
    System.out.println("getCurrentDir called ");
     if( currentDir == null ) return null ;
     return currentDir.getAbsolutePath();
  }
    
 
/**
* This method sets the currentDir, then works back through the parents 
* creating the parentDirs array of File objects.
* @param    File that will become the current directory, must be a directory
* @see  setCurrentDir
*/  
  private void setParentDirs( File f ){
    currentDir = f ;
    ArrayList list = new ArrayList( );
    File pf = f.getParentFile();
    while( pf != null ){
      list.add( pf ); f = pf ;
      System.out.println( "Parent: " + pf.getAbsolutePath() );
      pf = f.getParentFile();
    }
    // now reverse into array for clarity
    int ct = list.size();
    parentDirs = new File[ ct ] ;
    for( int n = 0 ; ct > 0 ; n++ ){
      parentDirs[ n ] = (File)list.get( ct - 1 );
      ct-- ;
    }
    File[] cdF = currentDir.listFiles();
    if( cdF == null ){ // can happen if currentDir is not a Directory
      cdF = new File[0] ;
    }
    System.out.println("currentDir.listFiles result: " + cdF.length );
    getChildDirs( cdF );
    getChildFiles( cdF ); // apply filter?
  }
 
/** creates the childDirs array by examining each File in 
*  the input array, keeping those that are directories.
*/  
  private void getChildDirs( File[] f ){
    ArrayList list = new ArrayList();
    for( int i = 0 ; i < f.length ; i++ ){
      if( f[i].isDirectory() ){
        list.add( f[i] );
      }
    }
    childDirs = new File[ list.size() ];
    childDirs = (File[]) list.toArray( childDirs );
    System.out.println("childDirs size " + childDirs.length );
  }
 
/** Similar to getChildDirs except it keeps those that are files
* @param Array of File representing all contained in currentDir. 
*/
  private void getChildFiles( File[] f ){
    ArrayList list = new ArrayList();
    for( int i = 0 ; i < f.length ; i++ ){
      if( f[i].isFile() ){
        list.add( f[i] );
      }
    }
    childFiles = new File[ list.size() ];
    childFiles = (File[]) list.toArray( childFiles );
    System.out.println("childFiles size " + childFiles.length );
  }
  
  
/** This method is called from JSP to create the complete display 
*  used inside the form. Note the use of class attributes for CSS.
* @return HTML formatted String
*/
  public String generateFileList(  ){
    StringWriter sW = new StringWriter( 2000 );
    PrintWriter out = new PrintWriter( sW );
    out.println("<ul>"); // disk root
    String rootS = parentDirs[0].getAbsolutePath();
    if( dirIsSelectable( rootS ) ){
      out.println("<li class=\"dir\" href=\"" +
          selectAlias + "?dir=" + rootS + "\" >" +
          rootS + "</a>" );
    } else {
      out.println("<li class=\"block\"> " + rootS );
    }
    for( int i = 1 ; i < parentDirs.length ; i++ ){
      out.println("<ul>");
      String tmp = parentDirs[ i ].getAbsolutePath();
      int p = tmp.lastIndexOf( File.separatorChar );
      if( dirIsSelectable( tmp ) ){
        out.println("<li><a class=\"dir\" href=\"" +
          selectAlias + "?dir=" + tmp + "\" >" +
          tmp.substring( p + 1 ) + "</a>" );
      }
      else {
        out.println("<li class=\"block\">" + tmp.substring( p + 1 ) );
      }
    } // now for the current top
    out.println("<ul><li class=\"dir\">" + currentDir.getName());
    out.println("<ul>");
    listDirs( out );
    listFiles( out );   
    out.println("</ul>");
    for( int i = 0 ; i < parentDirs.length ; i++ ){
      out.println("</ul>");
    } // close out the list
    if( legalDirs.length > 1 ){
       showOtherRoots( out ); // still inside first <ul>
    }
    out.println("</ul>");
    out.flush();
    return sW.toString();
  }
 
/** Writes HTML list of all legalDirs
* @param PrintWriter that writes to a StringWriter created in 
*   the generateFileList method.
*/  
  public void showOtherRoots( PrintWriter out ){
    for( int i = 0 ; i < legalDirs.length ; i++ ){
      out.println( "<li><a class=\"dir\" href=\"" +
        selectAlias + "?dir=" + legalDirs[i] + "\" >" +
        legalDirs[i] + "</a>" );
    }
  }
  
  // these are the dirs contained in the currentDir
  private void listDirs(PrintWriter out ){ // could insert sort here
    // must sort BEFORE the following
    String[] names = new String[ childDirs.length ] ;
    for( int i = 0 ; i < childDirs.length ; i++ ){
      names[i] = "<li><a  class=\"dir\" href=\"" +
         selectAlias + "?dir=" + childDirs[i].getAbsolutePath() 
         + "\" > " + 
         childDirs[i].getName() +
         "</a>" ;
      out.println( names[i] );
    }
  }
  
  private void listFiles( PrintWriter out){
    // must sort BEFORE the following
    String[] names = new String[ childFiles.length ] ;
    for( int i = 0 ; i < childFiles.length ; i++ ){
      String fn = childFiles[i].getName();
      if( !fn.endsWith( fileSel )) continue ;
      names[i] = "<li><a class=\"file\" href=\"" +
         actionAlias + "?selected=" + childFiles[i].getAbsolutePath() 
         + "\" > " + fn + "</a>" ;
      out.println( names[i] );
    }
  }
 
  private boolean dirIsSelectable( String s ){
    for( int i = 0 ; i < legalDirs.length ; i++ ){
      if( s.startsWith( legalDirs[i] ) ) return true ;
    }  
    System.out.println("Not selectable:" + s );
    return false ;
  }
}

In the JSP you have to provide for setting the parameters that control which roots of the file system are browsable - the JSP I used looks like:

<%! // These become instance variables of the resulting servlet
  String[] legalDir = { 
     "c:\\JavaProjects\\TestEditorXML",  // note comma
     "x:\\Preplogic",
     "c:\\Servers\\Data\\NewTest"        // note no comma
       } ; // exact format required for this String array 
  String startDir = "c:\\JavaProjects\\TestEditorXML" ;
  String thisURL = "/" ;
  String actionURL = "/edit" ;
%>  
<jsp:useBean id="fileselect" scope="session" class="com.wbprep.util.FileSelectBean" 
    ></jsp:useBean>    
Starting point is <%= startDir %>
 
<%-- start the service method --%>
<% 
  if( fileselect.getCurrentDir() == null ){ // new bean
     fileselect.setCurrentDir( startDir );
     fileselect.setLegalRoots( legalDir );
     fileselect.setSelectAlias( thisURL );
     fileselect.setActionAlias( actionURL );
  }
  String dirchg = request.getParameter("dir");
  if( dirchg != null ){
     fileselect.setCurrentDir( dirchg );
  }
  System.out.println( new java.util.Date().toString() );
%>
<%= fileselect.generateFileList() %>
<br>

Note that the bean does all the HTML formatting and that CSS controls the appearance of directories and files.

Bill