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The Fedora Client is a Java Library that allows API access to a Fedora Repository. The client is typically one part of a full Fedora installation.
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/*
* -----------------------------------------------------------------------------
*
* License and Copyright: The contents of this file are subject to the
* Apache License, Version 2.0 (the "License"); you may not use
* this file except in compliance with the License. You may obtain a copy of
* the License at
* http://www.fedora-commons.org/licenses.
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The entire file consists of original code.
* Copyright © 2008 Fedora Commons, Inc.
*
Copyright © 2002-2007 The Rector and Visitors of the University of
* Virginia and Cornell University
* All rights reserved.
*
* -----------------------------------------------------------------------------
*/
package fedora.common;
import java.io.*; // BufferedReader, InputStreamReader
/**
* A persistent identifier for Fedora digital objects.
*
* The following describes the syntactic constraints for PIDs in normalized
* form. The only differences with non-normalized PIDs are that the
* colon delimiter may be encoded as "%3a" or "%3A", and hex-digits may
* use lowercase [a-f].
*
*
* PID:
* Length : maximum 64
* Syntax : namespace-id ":" object-id
*
* namespace-id:
* Syntax : ( [A-Z] / [a-z] / [0-9] / "-" / "." ) 1+
*
* object-id:
* Syntax : ( [A-Z] / [a-z] / [0-9] / "-" / "." / "~" / "_" / escaped-octet ) 1+
*
* escaped-octet:
* Syntax : "%" hex-digit hex-digit
*
* hex-digit:
* Syntax : [0-9] / [A-F]
*
*
* @version $Id: PID.java 4263 2005-07-20 15:51:38Z eddie $
* @author [email protected]
*/
public class PID {
/** The maximum length of a PID is 64. */
public static final int MAX_LENGTH = 64;
/** The reserved handle namespace id **/
public static final String NS_HANDLE = "hdl";
private String m_normalized;
private String m_namespaceId;
private String m_objectId;
private String m_filename;
/**
* Construct a PID from a string, throwing a MalformedPIDException
* if it's not well-formed.
*/
public PID(String pidString)
throws MalformedPIDException {
if (pidString.startsWith(Constants.FEDORA.uri)) {
pidString = pidString.substring(Constants.FEDORA.uri.length());
}
m_normalized = normalize(pidString);
String[] split = m_normalized.split(":");
m_namespaceId = split[0];
m_objectId = split[1];
}
/**
* Alternate constructor that throws an unchecked exception
* if it's not well-formed.
*/
public static PID getInstance(String pidString) {
try {
return new PID(pidString);
} catch (MalformedPIDException e) {
throw new RuntimeException("Malformed PID: " + e.getMessage(), e);
}
}
/**
* Construct a PID given a filename of the form produced by toFilename(),
* throwing a MalformedPIDException if it's not well-formed.
*/
public static PID fromFilename(String filenameString)
throws MalformedPIDException {
String decoded = filenameString.replaceFirst("_", ":");
if (decoded.endsWith("%")) {
decoded = decoded.substring(0, decoded.length() - 1) + ".";
}
return new PID(decoded);
}
/**
* Return the normalized form of the given pid string,
* or throw a MalformedPIDException.
*/
public static String normalize(String pidString)
throws MalformedPIDException {
if (pidString == null) {
throw new MalformedPIDException("PID is null.");
}
// Then normalize while checking syntax
StringBuffer out = new StringBuffer();
boolean inObjectID = false;
for (int i = 0; i < pidString.length(); i++) {
char c = pidString.charAt(i);
if (!inObjectID) {
if (c == ':') {
out.append(':');
inObjectID = true;
} else if (c == '%') {
// next 2 chars MUST be 3[aA]
if (pidString.length() >= i + 3) {
i++;
if (pidString.charAt(i) == '3') {
i++;
c = pidString.charAt(i);
if ( c == 'a' || c == 'A' ) {
out.append(":");
inObjectID = true;
} else {
throw new MalformedPIDException("Error in PID after first '%': expected '3a' or '3A', but saw '3" + c + "'.");
}
} else {
throw new MalformedPIDException("Error in PID after first '%': expected '3a' or '3A', but saw '" + pidString.substring(i, i+2) + "'.");
}
} else {
throw new MalformedPIDException("Error in PID after first '%': expected '3a' or '3A', but saw '" + pidString.substring(i+1) + "'.");
}
} else if (isAlphaNum(c) || c == '-' || c == '.') {
out.append(c);
} else {
// invalid char for namespace-id
throw new MalformedPIDException("PID namespace-id cannot contain '" + c + "' character.");
}
} else if (isAlphaNum(c) || c == '-' || c == '.' || c == '~' || c == '_' ) {
out.append(c);
} else if (c == '%') {
// next 2 chars MUST be [0-9][a-f][A-F]
if (pidString.length() >= i + 3) {
char h1 = getNormalizedHexChar(pidString.charAt(++i));
char h2 = getNormalizedHexChar(pidString.charAt(++i));
out.append("%" + h1 + h2);
} else {
throw new MalformedPIDException("PID object-id ended early: need at least 2 chars after '%'.");
}
} else {
throw new MalformedPIDException("PID object-id cannot contain '" + c + "' character.");
}
}
if (!inObjectID) throw new MalformedPIDException("PID delimiter (:) is missing.");
String outString = out.toString();
if (outString.startsWith(":")) throw new MalformedPIDException("PID namespace-id cannot be empty.");
if (outString.length() < 3) throw new MalformedPIDException("PID object-id cannot be empty.");
if (outString.length() > MAX_LENGTH) throw new MalformedPIDException("PID length exceeds " + MAX_LENGTH + ".");
// If we got here, it's well-formed, so return it.
return outString;
}
private static boolean isAlphaNum(char c) {
return ( ( ( c >= '0' ) && ( c <= '9' ) )
|| ( ( c >= 'a' ) && ( c <= 'z' ) )
|| ( ( c >= 'A' ) && ( c <= 'Z' ) ) );
}
private static char getNormalizedHexChar(char c)
throws MalformedPIDException {
if ( c >= '0' && c <= '9' ) return c;
c = ("" + c).toUpperCase().charAt(0);
if ( c >= 'A' && c <= 'F' ) return c;
throw new MalformedPIDException("Bad hex-digit in PID object-id: " + c);
}
/**
* Return the normalized form of this PID.
*/
public String toString() {
return m_normalized;
}
/**
* Return the URI form of this PID.
*
* This is just the PID, prepended with "info:fedora/".
*/
public String toURI() {
return Constants.FEDORA.uri + m_normalized;
}
/**
* Return the URI form of some PID string, assuming it is well-formed.
*/
public static String toURI(String pidString) {
return Constants.FEDORA.uri + pidString;
}
/**
* Return a string representing this PID that can be safely used
* as a filename on any OS.
*
*
* - The colon (:) is replaced with an underscore (_).
* - Trailing dots are encoded as percents (%).
*
*/
public String toFilename() {
if (m_filename == null) { // lazily convert, since not always needed
m_filename = m_normalized.replaceAll(":", "_");
if (m_filename.endsWith(".")) {
m_filename = m_filename.substring(0, m_filename.length() - 1) + "%";
}
}
return m_filename;
}
public String getNamespaceId() {
return m_namespaceId;
}
public String getObjectId() {
return m_objectId;
}
/**
* Command-line interactive tester.
*
* If one arg given, prints normalized form of that PID and exits.
* If no args, enters interactive mode.
*/
public static void main(String[] args) throws Exception {
if (args.length > 0) {
PID p = new PID(args[0]);
System.out.println("Normalized : " + p.toString());
System.out.println("To filename : " + p.toFilename());
System.out.println("From filename : " + PID.fromFilename(p.toFilename()).toString());
} else {
System.out.println("--------------------------------------");
System.out.println("PID Syntax Checker - Interactive mode");
System.out.println("--------------------------------------");
boolean done = false;
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (!done) {
try {
System.out.print("Enter a PID (ENTER to exit): ");
String line = reader.readLine();
if (line.equals("")) {
done = true;
} else {
PID p = new PID(line);
System.out.println("Normalized : " + p.toString());
System.out.println("To filename : " + p.toFilename());
System.out.println("From filename : " + PID.fromFilename(p.toFilename()).toString());
}
} catch (MalformedPIDException e) {
System.out.println("ERROR: " + e.getMessage());
}
}
}
}
}
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