Metacat

/**

 *        Name: DBSAXElement.java

 *     Purpose: A Class that represents an XML element and its contents

 * Institution: National Center for Ecological Analysis and Synthesis

 *   Copyright: 2000

 *     Authors: Matt Jones

 *

 *     Version: '$Id: DBSAXElement.java 19 2000-04-11 17:57:28Z jones $'

 */

//package project;

import java.sql.*;

import java.io.IOException;

import java.util.Hashtable;

import java.util.Enumeration;

public class DBSAXElement {

    private long		element_id;

    private String		tagname;

    private StringBuffer	content;

    private long		parent_id;

    private Hashtable		attributes;

    private Connection		conn;

    public DBSAXElement (Connection conn, String tagname, 

                         long parent_id) {

      this.conn = conn;

      this.tagname = tagname;

      this.parent_id = parent_id;

      content = new StringBuffer();

      attributes = new Hashtable(); 

      writeElementToDB();

    };

    /** creates SQL code and inserts new element into DB connection */

    private void writeElementToDB() {

        try {

          conn.setAutoCommit(false);

          PreparedStatement pstmt;

          if (parent_id != 0) {

            pstmt = conn.prepareStatement(

                "INSERT INTO xml_elements(nodeid, nodename, parentnodeid) " +

                "VALUES (null, ?, ?)");

          } else {

            pstmt = conn.prepareStatement(

                "INSERT INTO xml_elements(nodeid, nodename) " +

                "VALUES (null, ?)");

          }

          // Bind the values to the query

          pstmt.setString(1, getTagName());// The second ? is for NODENAME

          if (parent_id != 0) {

            pstmt.setLong(2, parent_id);

          }

          // Do the insertion

          pstmt.execute();

          pstmt.close();

          this.element_id = getAssignedElementID();

          conn.commit();

          conn.setAutoCommit(true);

        } catch (SQLException e) {

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

        }

    }

    /** look up the assigned element id from DB connection */

    private long getAssignedElementID() {

        long assigned_id=0;

        Statement stmt;

        try {

          stmt = conn.createStatement();

          stmt.execute("SELECT xml_elements_id_seq.currval FROM dual");

          try {

            ResultSet rs = stmt.getResultSet();

            try {

              boolean tableHasRows = rs.next();

              if (tableHasRows) {

                try {

                  assigned_id = rs.getLong(1);

                } catch (SQLException e) {

                  System.out.println("Error with getInt: " + e.getMessage());

                }

              }

            } catch (SQLException e) {

              System.out.println("Error with next: " + e.getMessage());

            }

          } catch (SQLException e) {

            System.out.println("Error with getrset: " + e.getMessage());

          }

          stmt.close();

        } catch (SQLException e) {

          System.out.println("Error getting id: " + e.getMessage());

        }

        // assign the new ID number

        return assigned_id;

    }

    // used by JTree to display this node

    public String toString ()

    {

	StringBuffer	value = new StringBuffer ();

	value.append ('<');

	value.append (getTagName ());

	value.append (getAttributes ().toString ());

	value.append ('>');

	return value.toString ();

    }

    /** Get the id of this element */

    public long  getElementID() { return element_id; }

    /** Get the name of this element */

    public String  getTagName() { return tagname; }

    /** Get the attributes as a string */

    public String getAttributes() {

      StringBuffer buf = new StringBuffer();

      String attName = null;

      String attValue = null;

      Enumeration attList = attributes.keys();

      while (attList.hasMoreElements()) {

        attName = (String)attList.nextElement();

        attValue = (String)attributes.get(attName);

        buf.append(" ").append(attName).append("=").append(attValue);        

      }

      return buf.toString();      

    }

    /** Add a new attribute to this element, or set its value */

    public void setAttribute(String attName, String attValue) {

      if (attName != null) {

        // Enter the attribute in the hash table

        attributes.put(attName, attValue);

        // And enter the attribute in the database

        try {

          PreparedStatement pstmt = conn.prepareStatement(

              "INSERT INTO xml_attributes(attributeid, nodeid, " +

              "attributename, attributevalue) " +

              "VALUES (null, ?, ?, ?)");

          // Bind the values to the query

          pstmt.setLong(1, getElementID());

          pstmt.setString(2, attName);

          pstmt.setString(3, attValue);

          // Do the insertion

          pstmt.execute();

          pstmt.close();

        } catch (SQLException e) {

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

        }

      } else {

        System.err.println("Attribute name must not be null!");

      }

    }

    /** Get an attribute value by name */

    public String getAttribute(String attName) {

      return (String)attributes.get(attName);

    }

    /** Append to the content of the element */

    public void appendContent(char[] cbuf, int start, int len) {

      this.content.append( cbuf, start, len );

    }

    /** Append to the content of the element */

    public void appendContent(String new_content) {

      this.content.append( new_content );

    }

    /** Get the content of the element */

    public String getContent() {

      return this.content.toString();

    }

    /** Write the element content to the db connection */

    public void writeContentToDB() {

        try {

          PreparedStatement pstmt = conn.prepareStatement(

                "UPDATE xml_elements SET nodedata = ? WHERE nodeid = ?");

          // Bind the values to the query

          pstmt.setString(1, getContent());// The first ? is for NODEDATA

          pstmt.setLong(2, element_id); // The second ? is for NODEID

          // Do the update

          pstmt.execute();

          pstmt.close();

        } catch (SQLException e) {

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

        }

    }

}