net.oauth.jsontoken.SystemClock.java Source code

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Here is the source code for net.oauth.jsontoken.SystemClock.java

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/**
 * Copyright 2010 Google Inc.
 *
 * Licensed under 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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */
package net.oauth.jsontoken;

import org.joda.time.Duration;
import org.joda.time.Instant;
import org.joda.time.Interval;

/**
 * Default implementation of {@link Clock}, which accepts clock skews (when comparing time
 * instances) of up to 2 minutes.
 */
public class SystemClock implements Clock {

    public static final Duration DEFAULT_ACCEPTABLE_CLOCK_SKEW = Duration.standardMinutes(2);

    private final Duration acceptableClockSkew;

    /**
     * Public constructor.
     */
    public SystemClock() {
        this(DEFAULT_ACCEPTABLE_CLOCK_SKEW);
    }

    /**
     * Public constructor.
     * @param acceptableClockSkew the current time will be considered inside the
     *   interval at {@link #isCurrentTimeInInterval(Instant, Duration)} even if the current time
     *   is up to acceptableClockSkew off the ends of the interval.
     */
    public SystemClock(Duration acceptableClockSkew) {
        this.acceptableClockSkew = acceptableClockSkew;
    }

    /*
     * (non-Javadoc)
     * @see net.oauth.jsontoken.Clock#now()
     */
    @Override
    public Instant now() {
        return new Instant();
    }

    /**
     * Determines whether the current time (plus minus the acceptableClockSkew) falls within the
     * interval defined by the start and intervalLength parameters.
     */
    @Override
    public boolean isCurrentTimeInInterval(Instant start, Instant end) {
        Interval interval = new Interval(start, end);
        Instant now = now();
        Interval currentTimeWithSkew = new Interval(now.minus(acceptableClockSkew), now.plus(acceptableClockSkew));
        return interval.overlaps(currentTimeWithSkew);
    }
}