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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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* Institution: National Center for Ecological Analysis and Synthesis
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* Copyright: 2000
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* Authors: Matt Jones
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*
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* Version: '$Id: DBReader.java 21 2000-04-11 20:26:43Z jones $'
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*/
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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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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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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 nodeid = args[0];
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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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DBReader rd = new DBReader(user, password, dbstring);
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String xml = rd.readDocument(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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private DBReader( String user, String password, String dbstring)
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throws IOException,
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SQLException,
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ClassNotFoundException
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{
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// Open a connection to the database
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conn = openDBConnection(
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"oracle.jdbc.driver.OracleDriver",
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dbstring, user, password);
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}
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private Connection openDBConnection(String dbDriver, String connection,
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String user, String password)
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throws SQLException, ClassNotFoundException {
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// Load the Oracle JDBC driver
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Class.forName (dbDriver);
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// Connect to the database
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Connection conn = DriverManager.getConnection( connection, user, password);
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return conn;
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}
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public String readDocument(String nodeid) {
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StringBuffer doc = new StringBuffer();
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System.out.println("\nGetting document with nodeid: " + nodeid + "\n");
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BasicElement element = readNodeFromDB(nodeid);
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doc.append(element);
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return (doc.toString());
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}
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/** look up the assigned element id from DB connection */
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private BasicElement readNodeFromDB(String nodeid) {
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long element_id=0;
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long nodeparentid=0;
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String nodetype=null;
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String nodename=null;
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String nodedata=null;
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PreparedStatement pstmt;
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try {
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pstmt =
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conn.prepareStatement("SELECT nodeid,nodeparentid,nodetype,
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nodename,nodedata FROM xml_nodes WHERE nodeid = ?");
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// Bind the values to the query
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pstmt.setString(1, nodeid);
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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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element_id = rs.getLong(1);
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nodeparentid = rs.getLong(2);
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nodetype = rs.getString(3);
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nodename = rs.getString(4);
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nodedata = rs.getString(5);
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} catch (SQLException e) {
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System.out.println("Error with getInt: " + 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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if (nodetype.equals("ELEMENT")) {
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BasicElement element =
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new BasicElement(element_id,nodename,nodeparentid);
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element.appendContent(nodedata);
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}
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// Get a list of child nodes and recursively retrieve them as well
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try {
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pstmt =
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conn.prepareStatement("SELECT nodeid,nodeparentid,nodetype, " +
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"nodename,nodedata FROM xml_nodes " +
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"WHERE nodeparentid = ?");
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// Bind the values to the query
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pstmt.setString(1, nodeid);
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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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element_id = rs.getLong(1);
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nodeparentid = rs.getLong(2);
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nodetype = rs.getString(3);
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nodename = rs.getString(4);
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nodedata = rs.getString(5);
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} catch (SQLException e) {
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System.out.println("Error with getInt: " + 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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174
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return element;
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}
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}
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