我确实决定自己编写代码。使用风险自负:-)
/*
* NumberExpression.java - a simple number expression parser
*
* Copyright (c) 2010 Michael Schierl
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions 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 name of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND THE CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package numberexpression;
/**
* An expression that matches nonnegative numbers. This supports cron-like
* expressions, like <code>1,3-6,100-200,666,1000-3000/5,400-/7</code>,
* <code>-100,102-</code> or <code>*</code>. Odd or even numbers can be
* matched either by cron's step syntax, or by suffixing a simple range
* (without step values) with <code>e</code> or <code>o</code>.
*
* @author Michael Schierl
*/
public class NumberExpression {
private final NumberRange[] ranges;
private final int min, max;
/**
* Create a new {@link NumberExpression}.
*
* @param pattern
* the expression pattern.
* @throws IllegalArgumentException
* if the pattern is malformed
*/
public NumberExpression(String pattern) {
String[] parts = pattern.toLowerCase().split(",",-1);
ranges = new NumberRange[parts.length];
int min = Integer.MAX_VALUE, max = 0;
for (int i = 0; i < ranges.length; i++) {
String part = parts[i];
try {
if (part.equals("*")) {
ranges[i] = new NumberRange(0, Integer.MAX_VALUE, 0, 1);
} else if (part.matches("\\*/\\d+")) {
ranges[i] = new NumberRange(0, Integer.MAX_VALUE, 0, Integer.parseInt(part.substring(2)));
} else if (part.matches("\\d+")) {
int value = Integer.parseInt(part);
ranges[i] = new NumberRange(value, value, 0, 1);
} else if (part.matches("\\d*-\\d*")) {
String[] limits = part.split("-", -1);
int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
if (to < from)
throw new IllegalArgumentException("Invalid pattern: " + part);
ranges[i] = new NumberRange(from, to, 0, 1);
} else if (part.matches("\\d*-\\d*/\\d+")) {
String[] rangeAndModulus = part.split("/", -1);
String[] limits = rangeAndModulus[0].split("-", -1);
int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
int modulus = Integer.parseInt(rangeAndModulus[1]);
if (to < from)
throw new IllegalArgumentException("Invalid pattern: " + part);
ranges[i] = new NumberRange(from, to, from % modulus, modulus);
} else if (part.matches("\\d*-\\d*[eo]")) {
String[] limits = part.substring(0, part.length() - 1).split("-", -1);
int from = limits[0].length() == 0 ? 0 : Integer.parseInt(limits[0]);
int to = limits[1].length() == 0 ? Integer.MAX_VALUE : Integer.parseInt(limits[1]);
if (to < from)
throw new IllegalArgumentException("Invalid pattern: " + part);
ranges[i] = new NumberRange(from, to, part.charAt(part.length() - 1) == 'o' ? 1 : 0, 2);
} else {
throw new IllegalArgumentException("Invalid pattern: " + part);
}
max = Math.max(max, ranges[i].getMax());
min = Math.min(min, ranges[i].getMin());
} catch (NumberFormatException ex) {
throw new IllegalArgumentException("Invalid pattern: " + part);
}
}
this.max = max;
this.min = min;
}
/**
* Check whether this number expression matches the given number.
*
* @param number
* the number to check against
* @return whether the expression matches the number
*/
public boolean matches(int number) {
if (number < min || number > max)
return false;
for (int i = 0; i < ranges.length; i++) {
if (ranges[i].matches(number))
return true;
}
return false;
}
/**
* Return the minimum number that can be matched.
*/
public int getMinimum() { return min; }
/**
* Return the maximum number that can be matched.
*/
public int getMaximum() { return max; }
private static class NumberRange {
private final int min, max, remainder, modulus;
NumberRange(int min, int max, int remainder, int modulus) {
this.min = min;
this.max = max;
this.remainder = remainder;
this.modulus = modulus;
}
boolean matches(int number) {
return number >= min && number <= max && number % modulus == remainder;
}
int getMin() { return min; }
int getMax() { return max; }
}
}