Metacat

/**

 *        Name: DBSimpleQuery.java

 *     Purpose: A Class that searches a relational DB for XPath expressions

 *              and returns a reult set consisting of the root nodeid for

 *              each document that satisfies the query

 * Institution: National Center for Ecological Analysis and Synthesis

 *   Copyright: 2000

 *     Authors: Matt Jones

 *

 *     Version: '$Id: DBSimpleQuery.java 28 2000-04-12 01:54:06Z jones $'

 */

import java.io.*;

import java.net.URL;

import java.net.MalformedURLException;

import java.sql.*;

import java.util.Stack;

import java.util.Hashtable;

import java.util.Enumeration;

public class DBSimpleQuery {

  static  String 	defaultDB = "jdbc:oracle:thin:@localhost:1521:test";

  private Connection	conn = null;

  static public void main(String[] args) {

     if (args.length < 3)

     {

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

        System.err.println("USAGE: java DBSimpleQuery " +

                           "<query> <user> <password> [dbstring]");

        return;

     } else {

        try {

          String query    = args[0];

          String user     = args[1];

          String password = args[2];

          String dbstring = null;

          if (args.length <= 3) {

            dbstring = defaultDB;

          } else {

            dbstring = args[3];

          }

          // Execute the simple query

          DBSimpleQuery rd = new DBSimpleQuery(user, password, dbstring);

          Hashtable nodelist = rd.findRootNodes(query);

          // Print the reulting root nodes

          StringBuffer result = new StringBuffer();

          long nodeid;

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

          result.append("<resultset>\n");

          Enumeration rootlist = nodelist.keys(); 

          while (rootlist.hasMoreElements()) {

            nodeid = ((Long)rootlist.nextElement()).longValue();

            result.append("  <nodeid>").append(nodeid).append("</nodeid>\n");

          }

          result.append("</resultset>");

          System.out.println(result);

        } catch (Exception e) {

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

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

          e.printStackTrace(System.err);

        }

     }

  }

  private DBSimpleQuery( String user, String password, String dbstring) 

                  throws IOException, 

                         SQLException, 

                         ClassNotFoundException

  {

     // Open a connection to the database

     conn = openDBConnection(

                "oracle.jdbc.driver.OracleDriver",

                dbstring, user, password);

  }

  private Connection openDBConnection(String dbDriver, String connection,

                String user, String password)

                throws SQLException, ClassNotFoundException {

     // Load the Oracle JDBC driver

     Class.forName (dbDriver);

     // Connect to the database

     Connection conn = DriverManager.getConnection( connection, user, password);

     return conn;

  }

  public Hashtable findRootNodes(String query) {

      Hashtable	nodeListResult = new Hashtable();

      Hashtable	rootListResult = new Hashtable();

      PreparedStatement pstmt;

      long nodeid;

      try {

        pstmt =

          conn.prepareStatement("SELECT nodeid " +

                  "FROM xml_nodes WHERE nodedata LIKE ?");

        // Bind the values to the query

        pstmt.setString(1, query);

        pstmt.execute();

        try {

          ResultSet rs = pstmt.getResultSet();

          try {

            boolean tableHasRows = rs.next();

            while (tableHasRows) {

              try {

                nodeid = rs.getLong(1);

                nodeListResult.put(new Long(nodeid),new Long(nodeid));

              } catch (SQLException e) {

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

              }

              // Advance to the next record in the cursor

              tableHasRows = rs.next();

            }

          } catch (SQLException e) {

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

          }

        } catch (SQLException e) {

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

        }

        pstmt.close();

      } catch (SQLException e) {

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

      }

      Enumeration nodelist = nodeListResult.keys(); 

      while (nodelist.hasMoreElements()) {

        nodeid = ((Long)nodelist.nextElement()).longValue();

        try {

          pstmt =

            conn.prepareStatement("SELECT nodeid " +

                    "FROM xml_nodes START WITH nodeid = ? " +

                    "CONNECT BY nodeid = PRIOR parentnodeid");

          // Bind the values to the query

          pstmt.setLong(1, nodeid);

          pstmt.execute();

          try {

            ResultSet rs = pstmt.getResultSet();

            try {

              boolean tableHasRows = rs.next();

              while (tableHasRows) {

                try {

                  nodeid = rs.getLong(1);

                } catch (SQLException e) {

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

                }

                // Advance to the next record in the cursor

                tableHasRows = rs.next();

              }

            } catch (SQLException e) {

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

            }

          } catch (SQLException e) {

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

          }

          pstmt.close();

        } catch (SQLException e) {

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

        }

        // Record that the last record should be the root

        rootListResult.put(new Long(nodeid),new Long(nodeid));

      } 

      return rootListResult;

  }

}