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/**
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* Name: DBReader.java
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* Purpose: A Class that creates an XML text document
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* from a query to a relational DB containing a DOM representation
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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jones
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* Authors: Matt Jones
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*
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* Version: '$Id$'
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*/
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package edu.ucsb.nceas.metacat;
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import java.io.*;
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import java.net.URL;
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import java.net.MalformedURLException;
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import java.sql.*;
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import java.util.Stack;
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31
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jones
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/**
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* A Class that creates an XML text document
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* from a query to a relational DB containing a DOM representation
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*/
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public class DBReader {
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static String defaultDB = "jdbc:oracle:thin:@localhost:1521:test";
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private Connection conn = null;
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/**
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* main routine used for testing.
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*
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* Usage: java DBReader <nodeid> <user> <password> [dbstring]
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*
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* @param nodeid the id number of the root of the subtree to display
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* @param user the username to use for the database connection
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* @param password the password to use for the database connection
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* @param dbstring the connection info to use for the database connection
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*/
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static public void main(String[] args) {
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if (args.length < 3)
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{
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System.err.println("Wrong number of arguments!!!");
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System.err.println("USAGE: java DBReader " +
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"<nodeid> <user> <password> [dbstring]");
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return;
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} else {
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try {
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String nodeidstr = args[0];
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long nodeid = (new Long(nodeidstr).longValue());
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String user = args[1];
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String password = args[2];
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String dbstring = null;
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if (args.length <= 3) {
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dbstring = defaultDB;
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} else {
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dbstring = args[3];
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}
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// Open a connection to the database
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Connection dbconn = MetaCatUtil.openDBConnection(
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"oracle.jdbc.driver.OracleDriver",
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dbstring, user, password);
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DBReader rd = new DBReader( dbconn );
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String xml = rd.readXMLDocument(nodeid);
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System.out.println(xml);
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} catch (Exception e) {
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System.err.println("EXCEPTION HANDLING REQUIRED");
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System.err.println(e.getMessage());
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e.printStackTrace(System.err);
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}
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}
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}
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/**
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* construct a DBReader instance.
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*
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* Generally, one calls readXMLDocument() after constructing the instance
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*
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* @param conn the database connection from which to read the document
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*/
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public DBReader( Connection conn )
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throws IOException,
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SQLException,
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ClassNotFoundException
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{
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this.conn = conn;
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}
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/**
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* Get the root node id for an XML document given a document id
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*
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* @param docid the document node contains the root of the document
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* @returns long the nodeid of the root node for this document
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*/
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public long getRootNode(long docid) {
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// Now look up the root node id
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long rootnodeid = 0;
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try {
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PreparedStatement pstmt =
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conn.prepareStatement("SELECT rootnodeid " +
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"FROM xml_documents " +
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"WHERE docid = ?");
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// Bind the values to the query
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pstmt.setLong(1, docid);
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pstmt.execute();
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try {
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ResultSet rs = pstmt.getResultSet();
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try {
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boolean tableHasRows = rs.next();
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if (tableHasRows) {
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try {
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rootnodeid = rs.getLong(1);
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} catch (SQLException e) {
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System.out.println("Error with getLong: " + e.getMessage());
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}
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}
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} catch (SQLException e) {
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System.out.println("Error with next: " + e.getMessage());
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}
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} catch (SQLException e) {
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System.out.println("Error with getrset: " + e.getMessage());
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}
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pstmt.close();
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} catch (SQLException e) {
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System.out.println("Error getting id: " + e.getMessage());
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}
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return rootnodeid;
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}
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/**
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31
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jones
|
* Create an XML document from the database starting with the element
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* having element_id nodeid
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*
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86
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jones
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* @param docid the document that we want retrieved
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31
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jones
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*/
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86
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jones
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public String readXMLDocument(long docid) {
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21
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jones
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StringBuffer doc = new StringBuffer();
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86
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jones
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ReaderElement element = new ReaderElement(conn, getRootNode(docid));
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jones
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doc.append("<?xml version=\"1.0\"?>\n");
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doc.append(element.toString());
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21
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jones
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return (doc.toString());
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}
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}
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