cstreebean.java

b/s下jsp+javabean实现从数据库中读取数据生成目录树

					if(((labels[i] = rs.getString(labelColumns[i]))) == null || labels[i].length() == 0)
						break;
					if((urls[i] = rs.getString(urlColumns[i])) != null && urls[i].length() == 0)
						urls[i] = null;	// force empty url columns to null for easy testing later...
				}

				for(j=0; j < i-1; j++) {

					if(tn[j] == null || !labels[j].equals(tn[j].getName())) {	// then this is the first or a new item
						tn[j] = new TreeNode(nodeID++, labels[j], urls[j]);
						if(j > 0)
							tn[j-1].addChild(tn[j]);
						else
							root.addChild(tn[j]);
						continue;
					}
				}
				if(j > 0)
					tn[j-1].addChild( new TreeLeaf( labels[j], urls[j]) );
				else
					root.addChild(new TreeLeaf(labels[j],urls[j]));
			}

			trees.put(treeName, root);	// Store the tree in the static Hashtable

		} catch(SQLException e) {
			System.out.println(e.toString());
			sqlerror = true;
		}
	
		try {
			con.close();
		}
		catch(SQLException ignored) {}
		return !sqlerror;
	}

	/**
	 * This method is just a call to the method below with a null argument, meaning that the tree
	 * shouldn't get it's state from the session.
	 */
	public final String renderHTML() {
		return renderHTML((HttpServletRequest)null);
	}

	/**
	 * This method first of all builds a Hashtable of open nodes from the request parameter 
	 * for easy lookup later. It then submits the root node of the tree named in the bean 
	 * parameter 'treeName' (or the default tree) for rendering as HTML. If a HttpServletRequest
	 * is supplied, the method will try to obtain '<treeName>.oldopen' from the session.
	 */

	public final String renderHTML( HttpServletRequest req ) {

		if(populateJdbc() == false)	{		// ensures the tree is populated
			return "<p><strong>The CDTreeBean has not been successfully initialised. Check the server's stdout for details.</strong></p>";
		}

		// Try to obtain 'oldopen' from the session if a request object was passed
		if(req != null) {
			HttpSession s = req.getSession(false);
			String tmp = s != null ? (String)s.getAttribute(treeName + ".oldopen") : null;
			if(tmp != null && tmp.length() > 0)
				oldopen = tmp;
		}

		// Make a hash table of the currently open nodes (from the URL parameter)

		StringTokenizer st = new StringTokenizer(oldopen, ":");
		String token;
		while(st.hasMoreElements()) {
			try {
				token = st.nextToken();
				openNodes.put(Integer.valueOf(token), token);
				// strb.append(token).append(":");
			} catch(NumberFormatException e) {
				System.out.println("Warning: TreeBean was passed dodgy parameters!");
			}
		}
		// now add the requested node to the open list (if not a close-request)
		if(open >= 0) {
			openNodes.put(new Integer(open), String.valueOf(open));
			// strb.append(open);
		} else {
			openNodes.remove(new Integer(-open));
		}
		StringBuffer strb = new StringBuffer();
		Enumeration on = openNodes.elements();
		while(on.hasMoreElements()) {
			strb.append(on.nextElement()).append(":");
		}
		this.oldopen = strb.toString();
		// Try to write 'oldopen' to the session if a request object was passed
		if(req != null) {
			HttpSession s = req.getSession(false);
			if(s != null)
				s.setAttribute(treeName + ".oldopen", oldopen);
		}

		StringBuffer html = new StringBuffer(renderHTML((Tree)trees.get(treeName)));

		return html.toString();
	}

	private boolean isVisible(TreeNode node) {
		if(openNodes.containsKey(new Integer(node.getId())))
			return true;
		return false;
	}

	/**
	 * Renders the specified tree as HTML by iterating over all it's children. Will call itself
	 * recursively for any visible node children.
	 */
	private final String renderHTML(Tree tree) {

		StringBuffer buf = new StringBuffer();

		buf.append("\n<TABLE border=\"0\"");
		if(treeStyle != null && treeStyle.length() > 0)
			buf.append(" class=\"").append(treeStyle).append("\"");
		buf.append(">\n");
		for( int i=0; i < tree.size(); i++ ) {
			TreeObject treeObject = tree.getChild(i);
			if( treeObject.getType() == Tree.NODE ) {
				TreeNode node = (TreeNode)treeObject;
				buf.append( renderNodeHTML(node) );
				if( isVisible(node) ) {
					buf.append("<tr><td>&nbsp;</td><td>").append( renderHTML( node.getChildren() ) ).append("</td></tr>");
				}
			}
			else {
				TreeLeaf leaf = (TreeLeaf)treeObject;
				buf.append( renderLeafHTML(leaf) );
			}
		}
		buf.append("\n</TABLE>\n");

		return buf.toString();
	}

	/**
	 * Renders the specified tree node as HTML.
	 */
	private final String renderNodeHTML(TreeNode node) {
		StringBuffer buf = new StringBuffer();
		boolean visible = isVisible(node);
		buf.append( "<tr><td><a ");
		if(absopen == node.getId())	// active link reference
			buf.append("name='A' ");
		buf.append("href='").append(treePage).append("?");
		buf.append("oldopen=").append(oldopen).append("&open=")
			.append(visible ? -(node.getId()) : node.getId())
			.append("' target=\"_self\">" );
		if( visible ) {
			buf.append( "<img src='").append(openImage).append("' border='0'>" );
		}
		else {
			buf.append( "<img src='").append(closedImage).append("' border='0'>" );
		}
		buf.append( "</a>" );
		buf.append( "</td><td>" );
		String link = node.getLink();
		if( link != null ) {
			buf.append( "<a href='");
			if(leafPage != null && leafPage.length() > 0)	// if a leafPage is specified, then prepend to the link
				buf.append(leafPage);
			buf.append(link).append("' ");

			if(leafTarget != null && leafTarget.length() > 0)
				buf.append("target='").append(leafTarget).append("'");

			buf.append(">" ).append( node.getName() ).append( "</a>" );
		}
		else {
			buf.append( node.getName() );
		}
		buf.append( "</td></tr>" );
		return buf.toString();
	}

	/**
	 * Renders the specified tree leaf as HTML.
	 */
	private final String renderLeafHTML( TreeLeaf leaf ) {

		StringBuffer buf = new StringBuffer();
		buf.append( "<tr><td>").append("<img src='").append(leafImage).append("' border='0'>")
			.append("</td><td><a href='");

		if(leafPage != null && leafPage.length() > 0)	// if a leafPage is specified, then prepend to the link
			buf.append(leafPage);

		buf.append(leaf.getLink()).append("' ");

		if(leafTarget != null && leafTarget.length() > 0)
			buf.append("target='").append(leafTarget).append("'");
		buf.append(">").append( leaf.getName() ).append( "</a></td></tr>" );

		return buf.toString();
	}

	/**
	 * Accepts a comma separated list of tokens and returns them as a string array.
	 */

	private String[] csvToArray(String csv) {

		StringTokenizer st = new StringTokenizer(csv,",");
		String[] buf = new String[st.countTokens()];

		int i = 0;
		while(st.hasMoreTokens())
			buf[i++] = st.nextToken();

		return buf;
	}

	public String adjustScrollPosition() {
//		return "<SCRIPT> window.location.href=\"#A\"; if(window.scrollTo) scrollTo(0,(document.body ? document.body.scrollTop : pageYOffset) - 20); </SCRIPT>";
		return "<SCRIPT> window.location.href=\"#A\"; window.scroll(0, -20); </SCRIPT>";
	}
}