Metacat

/**

 *        Name: DBReader.java

 *     Purpose: A Class that creates an XML text document

 *              from a query to a relational DB containing a DOM representation

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

 *              National Center for Ecological Analysis and Synthesis

 *     Authors: Matt Jones

 *

 *     Version: '$Id: DBReader.java 51 2000-04-17 23:06:07Z jones $'

 */

package edu.ucsb.nceas.metacat;

import java.io.*;

import java.net.URL;

import java.net.MalformedURLException;

import java.sql.*;

import java.util.Stack;

/** 

 * A Class that creates an XML text document

 * from a query to a relational DB containing a DOM representation

 */

public class DBReader {

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

  private Connection	conn = null;

  /**

   * main routine used for testing.

   *

   * Usage: java DBReader <nodeid> <user> <password> [dbstring]

   *

   * @param nodeid the id number of the root of the subtree to display

   * @param user the username to use for the database connection

   * @param password the password to use for the database connection

   * @param dbstring the connection info to use for the database connection

   */

  static public void main(String[] args) {

     if (args.length < 3)

     {

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

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

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

        return;

     } else {

        try {

          String nodeidstr = args[0];

          long nodeid = (new Long(nodeidstr).longValue());

          String user     = args[1];

          String password = args[2];

          String dbstring = null;

          if (args.length <= 3) {

            dbstring = defaultDB;

          } else {

            dbstring = args[3];

          }

          // Open a connection to the database

          Connection dbconn = MetaCatUtil.openDBConnection(

                "oracle.jdbc.driver.OracleDriver",

                dbstring, user, password);

          DBReader rd = new DBReader( dbconn );

          String xml = rd.readXMLDocument(nodeid);

          System.out.println(xml);

        } catch (Exception e) {

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

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

          e.printStackTrace(System.err);

        }

     }

  }

  /**

   * construct a DBReader instance.

   *

   * Generally, one calls readXMLDocument() after constructing the instance

   *

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

   */

  public DBReader( Connection conn ) 

                  throws IOException, 

                         SQLException, 

                         ClassNotFoundException

  {

    this.conn = conn;

  }

  /**

   * Create an XML document from the database starting with the element 

   * having element_id nodeid

   *

   * @param nodeid the node that will represent the root of the document

   */

  public String readXMLDocument(long nodeid) {

    StringBuffer doc = new StringBuffer();

    ReaderElement element = new ReaderElement(conn, nodeid);

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

    doc.append(element.toString());

    return (doc.toString());

  }

}