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/**
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* '$RCSfile$'
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* Purpose: A Class that implements utility methods for a metadata catalog
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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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* Authors: Matt Jones, Jivka Bojilova
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* Release: @release@
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*
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* '$Author: bojilova $'
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* '$Date: 2001-05-08 14:40:46 -0700 (Tue, 08 May 2001) $'
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* '$Revision: 739 $'
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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package edu.ucsb.nceas.metacat;
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import java.io.File;
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import java.net.URL;
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import java.net.MalformedURLException;
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import java.sql.Connection;
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import java.sql.DriverManager;
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import java.sql.SQLException;
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import java.util.PropertyResourceBundle;
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import java.util.Hashtable;
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import java.util.Enumeration;
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/**
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* A suite of utility classes for the metadata catalog server
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*/
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public class MetaCatUtil {
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private PropertyResourceBundle options = null;
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private String propertiesFile = "edu.ucsb.nceas.metacat.metacat";
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private Hashtable connectionPool = new Hashtable();
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private static boolean debug = false;
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/**
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* Construct an instance of the utility class
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*/
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public MetaCatUtil() {
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options = (PropertyResourceBundle)
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PropertyResourceBundle.getBundle(propertiesFile);
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}
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/**
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* This constructor allows the usage of a different properties file
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* @param propFile the properties file that you wish to use.
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*/
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public MetaCatUtil(String propFile)
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{
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propertiesFile = propFile;
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}
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/**
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* Utility method to establish a JDBC database connection using connection
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* info from the properties file
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*/
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public Connection openDBConnection()
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throws SQLException, ClassNotFoundException {
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return openDBConnection(getOption("dbDriver"), getOption("defaultDB"),
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getOption("user"), getOption("password"));
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}
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/**
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* Utility method to establish a JDBC database connection
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*
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* @param dbDriver the string representing the database driver
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* @param connection the string representing the database connectin parameters
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* @param user name of the user to use for database connection
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* @param password password for the user to use for database connection
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*/
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public static 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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debugMessage("Opening connection: " + connection);
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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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/**
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* Utility method to get an option value from the properties file
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*
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* @param option_name the name of the option requested
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*/
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public String getOption(String option_name) {
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// Get the configuration file information
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if (options == null) {
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options = (PropertyResourceBundle)
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PropertyResourceBundle.getBundle(propertiesFile);
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}
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String value = (String)options.handleGetObject(option_name);
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return value;
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}
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/* Utility method to create and return a pool of Connection objects */
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public Hashtable getConnectionPool()
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throws SQLException, ClassNotFoundException {
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int initConn = (new Integer(getOption("initialConnections"))).intValue();
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for ( int i = 0; i < initConn; i++ ) {
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connectionPool.put( openDBConnection(), Boolean.FALSE );
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}
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return connectionPool;
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}
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/* Utility method to get a unused Connection object from the pool */
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public Connection getConnection()
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throws SQLException, ClassNotFoundException, Exception {
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Connection conn = null;
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Enumeration connections = connectionPool.keys();
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synchronized (connectionPool) {
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while (connections.hasMoreElements()) {
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conn = (Connection)connections.nextElement();
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Boolean b = (Boolean)connectionPool.get(conn);
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if (conn == null || conn.isClosed()) {
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// closed connection; replace it
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conn = openDBConnection();
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// update the pool to show this one taken
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connectionPool.put(conn, Boolean.TRUE);
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return conn;
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} else if (b == Boolean.FALSE) {
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// unused connection; test if it works and get it
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try {
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conn.setAutoCommit(true);
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} catch (SQLException e) {
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// problem with the connection, replace it
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conn = openDBConnection();
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}
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// update the pool to show this one taken
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connectionPool.put(conn, Boolean.TRUE);
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return conn;
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}
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}
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}
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// If we get here, there no free connections;
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// we need to make more
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int incConn = (new Integer(getOption("incrementConnections"))).intValue();
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int maxConn = (new Integer(getOption("maximumConnections"))).intValue();
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int k = connectionPool.size();
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if ( k >= maxConn ) {
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throw new Exception("The maximum of " + maxConn +
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" open db connections is reached." +
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" New db connection to MetaCat" +
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" cannot be established.");
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}
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// decide how many new connections to open; no more than the maximum
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if ( incConn > maxConn - k ) { incConn = maxConn - k; }
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// get them
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for ( int i = 0; i < incConn; i++ ) {
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connectionPool.put( openDBConnection(), Boolean.FALSE );
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}
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// Recurse to get one of the new connections
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return getConnection();
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}
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/* Utility method to give the connection back to the pool */
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public void returnConnection (Connection returned) {
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Connection conn;
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Enumeration connections = connectionPool.keys();
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try {
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if ( (returned != null) && !(returned.isClosed()) ) {
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while (connections.hasMoreElements()) {
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conn = (Connection)connections.nextElement();
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if ( conn == returned ) {
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connectionPool.put( conn, Boolean.FALSE );
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break;
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}
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}
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}
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} catch (SQLException e) {}
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}
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/* Return the size of the pool */
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public int getPoolSize() {
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return connectionPool.size();
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}
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/* Utility method to close all the connection from the pool */
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public void closeConnections() {
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Connection conn;
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Enumeration connections = connectionPool.keys();
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while (connections.hasMoreElements()) {
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conn = (Connection)connections.nextElement();
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try {
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if ( (conn != null) && !(conn.isClosed()) ) {
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conn.close();
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}
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} catch (SQLException e) {}
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}
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}
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/** Utility method to convert a file handle into a URL */
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public static URL fileToURL(File file)
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{
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String path = file.getAbsolutePath();
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String fSep = System.getProperty("file.separator");
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if (fSep != null && fSep.length() == 1)
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path = path.replace(fSep.charAt(0), '/');
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if (path.length() > 0 && path.charAt(0) != '/')
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path = '/' + path;
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try {
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return new URL("file", null, path);
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}
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catch (java.net.MalformedURLException e) {
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/* According to the spec this could only happen if the file
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protocol were not recognized. */
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throw new Error("unexpected MalformedURLException");
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}
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}
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/**
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* Utility method to parse the query part of a URL into parameters. This
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* method assumes the format of the query par tof the url is an
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* ampersand separated list of name/value pairs, with equal signs separating
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* the name from the value (e.g., name=tom&zip=99801 ). Returns a
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* has of the name value pairs, hashed on name.
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*/
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public static Hashtable parseQuery(String query) throws MalformedURLException
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{
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String[][] params = new String[200][2];
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Hashtable parameters = new Hashtable();
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String temp = "";
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boolean ampflag = true;
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boolean poundflag = false;
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int arrcount = 0;
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if ( query != null ) {
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for (int i=0; i < query.length(); i++) {
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// go throught the remainder of the query one character at a time.
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if (query.charAt(i) == '=') {
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// if the current char is a # then the preceding should be a name
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if (!poundflag && ampflag) {
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params[arrcount][0] = temp.trim();
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temp = "";
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} else {
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//if there are two #s or &s in a row throw an exception.
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throw new MalformedURLException("metacatURL: Two parameter names "+
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"not allowed in sequence");
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}
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poundflag = true;
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ampflag = false;
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} else if (query.charAt(i) == '&' || i == query.length()-1) {
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//the text preceding the & should be the param value.
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if (i == query.length() - 1) {
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//if at the end of the string grab the last value and append it.
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if (query.charAt(i) != '=') {
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//ignore an extra & on the end of the string
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temp += query.charAt(i);
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}
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}
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if (!ampflag && poundflag) {
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params[arrcount][1] = temp.trim();
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parameters.put(params[arrcount][0], params[arrcount][1]);
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temp = "";
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arrcount++; //increment the array to the next row.
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} else {
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//if there are two =s or &s in a row through an exception
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throw new MalformedURLException("metacatURL: Two parameter values "+
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"not allowed in sequence");
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}
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poundflag = false;
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ampflag = true;
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} else {
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//get the next character in the string
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temp += query.charAt(i);
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}
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}
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}
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return parameters;
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}
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/**
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* Utility method to print debugging messages
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*
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* @param flag an integer indicating the message number
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*/
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public static void debugMessage(int flag) {
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if (debug) {
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System.err.println("DEBUG FLAG: " + flag);
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}
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}
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/**
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* Utility method to print debugging messages
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*
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* @param flag an integer indicating the message number
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*/
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public static void debugMessage(String msg) {
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if (debug) {
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System.err.println(msg);
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}
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}
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}
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