Metacat

/**

 *  '$RCSfile$'

 *    Purpose: A Class that represents an XML document

 *  Copyright: 2000 Regents of the University of California and the

 *             National Center for Ecological Analysis and Synthesis

 *    Authors: Matt Jones

 *    Release: @release@

 *

 *   '$Author: jones $'

 *     '$Date: 2000-08-22 22:32:53 -0700 (Tue, 22 Aug 2000) $'

 * '$Revision: 393 $'

 */

package edu.ucsb.nceas.metacat;

import java.sql.*;

import java.io.PrintWriter;

import java.util.TreeSet;

/**

 * A class that represents an XML document. It can be created with a simple

 * document identifier from a database connection.

 */

public class DocumentImpl {

  private Connection conn = null;

  private String docid = null;

  private String docname = null;

  private String doctype = null;

  private String system_id = null;

  private long rootnodeid;

  private ElementNode rootNode = null;

  /**

   * Constructor, creates document from database connection

   *

   * @param conn the database connection from which to read the document

   * @param docid the identifier of the document to be created

   */

  public DocumentImpl(Connection conn, String docid) throws McdbException 

  {

    try {

      this.conn = conn;

      this.docid = docid;

      // Look up the document information

      getDocumentInfo(docid);

      // Download all of the document nodes using a single SQL query

      TreeSet nodeRecordList = getNodeRecordList(docid);

      // Create the elements from the downloaded data in the TreeSet

      rootNode = new ElementNode(nodeRecordList, rootnodeid);

    } catch (McdbException ex) {

      throw ex;

    } catch (Throwable t) {

      throw new McdbException("Error reading document " + docid + ".");

    }

  }

  /**

   * get the document name

   */

  public String getDocname() {

    return docname;

  }

  /**

   * get the document type (which is the PublicID)

   */

  public String getDoctype() {

    return doctype;

  }

  /**

   * get the system identifier

   */

  public String getSystemID() {

    return system_id;

  }

  /**

   * get the root node identifier

   */

  public long getRootNodeID() {

    return rootnodeid;

  }

  /**

   * Create an XML document from the database for the document with ID docid

   */

  public String toString()

  {

    StringBuffer doc = new StringBuffer();

    // Append the resulting document to the StringBuffer and return it

    doc.append("<?xml version=\"1.0\"?>\n");

    if (docname != null) {

      if ((doctype != null) && (system_id != null)) {

        doc.append("<!DOCTYPE " + docname + " PUBLIC \"" + doctype + 

                   "\" \"" + system_id + "\">\n");

      } else {

        doc.append("<!DOCTYPE " + docname + ">\n");

      }

    }

    doc.append(rootNode.toString());

    return (doc.toString());

  }

  /**

   * Look up the document type information from the database

   *

   * @param docid the id of the document to look up

   */

  private void getDocumentInfo(String docid) throws McdbException 

  {

    PreparedStatement pstmt;

    try {

      pstmt =

        conn.prepareStatement("SELECT docname,doctype,rootnodeid " +

                                "FROM xml_documents " +

                               "WHERE docid = ?");

      // Bind the values to the query

      pstmt.setString(1, docid);

      pstmt.execute();

      ResultSet rs = pstmt.getResultSet();

      boolean tableHasRows = rs.next();

      if (tableHasRows) {

        this.docname    = rs.getString(1);

        this.doctype    = rs.getString(2);

        this.rootnodeid = rs.getLong(3);

      } 

      pstmt.close();

      if (this.doctype != null) {

        pstmt =

          conn.prepareStatement("SELECT system_id " +

                                  "FROM xml_catalog " +

                                 "WHERE public_id = ?");

        // Bind the values to the query

        pstmt.setString(1, doctype);

        pstmt.execute();

        rs = pstmt.getResultSet();

        tableHasRows = rs.next();

        if (tableHasRows) {

          this.system_id  = rs.getString(1);

        } 

        pstmt.close();

      }

    } catch (SQLException e) {

      throw new McdbException("Error accessing database connection.", e);

    }

    if (this.docname == null) {

      throw new McdbDocNotFoundException("Document not found: " + docid);

    }

  }

  /**

   * Look up the node data from the database

   *

   * @param docid the id of the document to look up

   */

  private TreeSet getNodeRecordList(String docid) throws McdbException 

  {

    PreparedStatement pstmt;

    TreeSet nodeRecordList = new TreeSet(new NodeComparator());

    long nodeid = 0;

    long parentnodeid = 0;

    long nodeindex = 0;

    String nodetype = null;

    String nodename = null;

    String nodedata = null;

    try {

      pstmt =

      conn.prepareStatement("SELECT nodeid,parentnodeid,nodeindex, " +

           "nodetype,nodename,"+               

           "replace(" +

           "replace(" +

           "replace(nodedata,'&','&') " +

           ",'<','&lt;') " +

           ",'>','>') " +

           "FROM xml_nodes WHERE docid = ?");

      // Bind the values to the query

      pstmt.setString(1, docid);

      pstmt.execute();

      ResultSet rs = pstmt.getResultSet();

      boolean tableHasRows = rs.next();

      while (tableHasRows) {

        nodeid = rs.getLong(1);

        parentnodeid = rs.getLong(2);

        nodeindex = rs.getLong(3);

        nodetype = rs.getString(4);

        nodename = rs.getString(5);

        nodedata = rs.getString(6);

        // add the data to the node record list hashtable

        NodeRecord currentRecord = new NodeRecord(nodeid, parentnodeid, 

                                   nodeindex, nodetype, nodename, nodedata);

        nodeRecordList.add(currentRecord);

        // Advance to the next node

        tableHasRows = rs.next();

      } 

      pstmt.close();

    } catch (SQLException e) {

      throw new McdbException("Error accessing database connection.", e);

    }

    if (nodeRecordList != null) {

      return nodeRecordList;

    } else {

      throw new McdbException("Error getting node data: " + docid);

    }

  }

  /**

   * main routine used for testing.

   * <p>

   * Usage: java DocumentImpl <docid>

   *

   * @param docid the id number of the document to display

   */

  static public void main(String[] args) {

     if (args.length < 1)

     {

        System.err.println("Wrong number of arguments!!!");

        System.err.println("USAGE: java DocumentImpl <docid>");

        return;

     } else {

        try {

          String docid = args[0];

          // Open a connection to the database

          MetaCatUtil   util = new MetaCatUtil();

          Connection dbconn = util.openDBConnection();

          DocumentImpl xmldoc = new DocumentImpl( dbconn, docid );

          System.out.println(xmldoc);

        } catch (McdbException me) {

          me.toXml(new PrintWriter(System.err));

        } catch (Exception e) {

          System.err.println("EXCEPTION HANDLING REQUIRED");

          System.err.println(e.getMessage());

          e.printStackTrace(System.err);

        }

     }

  }

}