versionid.java

一个小公司要求给写的很简单的任务管理系统。

/*
 * @(#)VersionID.java	1.7 05/11/17
 * 
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility.
 */

package jnlp.sample.util;

import java.util.ArrayList;
import java.util.Arrays;

/**
 *   VersionID contains a JNLP version ID.
 *
 *  The VersionID also contains a prefix indicator that can
 *  be used when stored with a VersionString
 *
 */
public class VersionID implements Comparable {
    private String[] _tuple;   // Array of Integer or String objects
    private boolean  _usePrefixMatch;   // star (*) prefix
    private boolean  _useGreaterThan;  // plus (+) greather-than
    private boolean  _isCompound;       // and (&) operator
    private VersionID _rest;            // remaining part after the &
    
    /** Creates a VersionID object */
    public VersionID(String str) {
	_usePrefixMatch  = false;
	_useGreaterThan = false;
	_isCompound = false;
	if (str == null && str.length() == 0) {
	    _tuple = new String[0];
	    return;
	}

	// Check for compound
	int amp = str.indexOf("&");
	if (amp >= 0) {
	    _isCompound = true;
	    VersionID firstPart = new VersionID(str.substring(0, amp));
	    _rest = new VersionID(str.substring(amp+1));
	    _tuple = firstPart._tuple;
	    _usePrefixMatch = firstPart._usePrefixMatch;
	    _useGreaterThan = firstPart._useGreaterThan;
	} else {
	    // Check for postfix
	    if (str.endsWith("+")) {
	        _useGreaterThan = true;
	        str = str.substring(0, str.length() - 1);
	    } else if (str.endsWith("*")) {
	        _usePrefixMatch = true;
	        str = str.substring(0, str.length() - 1);
	    }
	
	    ArrayList list = new ArrayList();
	    int start = 0;
	    for(int i = 0; i < str.length(); i++) {
	        // Split at each separator character
	        if (".-_".indexOf(str.charAt(i)) != -1) {
		    if (start < i) {
		        String value = str.substring(start, i);
		        list.add(value);
		    }
		    start = i + 1;
	        }
	    }
	    if (start < str.length()) {
		list.add(str.substring(start, str.length()));
	    }	
   	    _tuple = new String[list.size()];
	    _tuple = (String[])list.toArray(_tuple);
	}
    }
    
    /** Returns true if no flags are set */
    public boolean isSimpleVersion() {
	return !_useGreaterThan && !_usePrefixMatch && !_isCompound;
    }
    
    /** Match 'this' versionID against vid. 
     *  The _usePrefixMatch/_useGreaterThan flag is used to determine if a 
     *  prefix match of an exact match should be performed
     *  if _isCompound, must match _rest also.
     */
    public boolean match(VersionID vid) {
	if (_isCompound) {
	    if (!_rest.match(vid)) {
		return false;
	    }
	}
	return (_usePrefixMatch) ? this.isPrefixMatch(vid) :
	    (_useGreaterThan) ? vid.isGreaterThanOrEqual(this) : 
		matchTuple(vid);
    }

    /** Compares if two version IDs are equal */
    public boolean equals(Object o) {
	if (matchTuple(o)) {
	     VersionID ov = (VersionID) o;
	     if (_rest == null || _rest.equals(ov._rest)) {
		if ((_useGreaterThan == ov._useGreaterThan) &&
		    (_usePrefixMatch == ov._usePrefixMatch)) {
			return true;
		}
	    }
	}
	return false;
    }

    /** Compares if two version IDs are equal */
    private boolean matchTuple(Object o) {
	// Check for null and type
	if (o == null || !(o instanceof VersionID)) return false;
	VersionID vid = (VersionID)o;
	
	// Normalize arrays
	String[] t1 = normalize(_tuple, vid._tuple.length);
	String[] t2 = normalize(vid._tuple, _tuple.length);
	
	// Check contents
	for(int i = 0; i < t1.length; i++) {
	    Object o1 = getValueAsObject(t1[i]);
	    Object o2 = getValueAsObject(t2[i]);
	    if (!o1.equals(o2)) return false;
	}
	return true;
    }
    
    private Object getValueAsObject(String value) {
	if (value.length() > 0 && value.charAt(0) != '-') {
	    try { return Integer.valueOf(value);
	    } catch(NumberFormatException nfe) { /* fall through */ }
	}
	return value;
    }
    
    public boolean isGreaterThan(VersionID vid) {
	return isGreaterThanOrEqualHelper(vid, false);
    }
    
    public boolean isGreaterThanOrEqual(VersionID vid) {
	return isGreaterThanOrEqualHelper(vid, true);
    }
    
    /** Compares if 'this' is greater than vid */
    private boolean isGreaterThanOrEqualHelper(VersionID vid, 
	boolean allowEqual) {

	if (_isCompound) {
	    if (!_rest.isGreaterThanOrEqualHelper(vid, allowEqual)) {
		return false;
	    }
	}
	// Normalize the two strings
	String[] t1 = normalize(_tuple, vid._tuple.length);
	String[] t2 = normalize(vid._tuple, _tuple.length);
	
	for(int i = 0; i < t1.length; i++) {
	    // Compare current element
	    Object e1 = getValueAsObject(t1[i]);
	    Object e2 = getValueAsObject(t2[i]);
	    if (e1.equals(e2)) {
		// So far so good
	    } else {
		if (e1 instanceof Integer && e2 instanceof Integer) {
		    return ((Integer)e1).intValue() > ((Integer)e2).intValue();
		} else {
		    String s1 = t1[i].toString();
		    String s2 = t2[i].toString();
		    return s1.compareTo(s2) > 0;
		}
		
	    }
	}
	// If we get here, they are equal
	return allowEqual;
    }
    
    /** Checks if 'this' is a prefix of vid */
    public boolean isPrefixMatch(VersionID vid) {

	if (_isCompound) {
	    if (!_rest.isPrefixMatch(vid)) {
		return false;
	    }
	}
	// Make sure that vid is at least as long as the prefix
	String[] t2 = normalize(vid._tuple, _tuple.length);
	
	for(int i = 0; i < _tuple.length; i++) {
	    Object e1 = _tuple[i];
	    Object e2 = t2[i];
	    if (e1.equals(e2)) {
		// So far so good
	    } else {
		// Not a prefix
		return false;
	    }
	}
	return true;
    }
    
    /** Normalize an array to a certain lengh */
    private String[] normalize(String[] list, int minlength) {
	if (list.length < minlength) {
	    // Need to do padding
	    String[] newlist = new String[minlength];
	    System.arraycopy(list, 0, newlist, 0, list.length);
	    Arrays.fill(newlist, list.length, newlist.length, "0");
	    return newlist;
	} else {
	    return list;
	}
    }
    
    public int compareTo(Object o) {
	if (o == null || !(o instanceof VersionID)) return -1;
	VersionID vid = (VersionID)o;
	return equals(vid) ? 0 : (isGreaterThanOrEqual(vid) ? 1 : -1);
    }
    /** Show it as a string */
    public String toString() {
	StringBuffer sb = new StringBuffer();
	for(int i = 0; i < _tuple.length -1; i++) {
	    sb.append(_tuple[i]);
	    sb.append('.');
	}
	if (_tuple.length > 0 ) sb.append(_tuple[_tuple.length - 1]);
	if (_usePrefixMatch) sb.append('+');
	return sb.toString();
    }
}