java工具类系列 (二.StopWatch)

 StopWatch 提供一个时间片记录的API,该类是有apache下lang包中提供的,另外可以参考spring框架中的一个类似工具类,实现效果稍微不同,但都是提供一个时间记录功能,见另一篇:http://blog.csdn.net/lxzo123/article/details/6608162

该工具类源码如下:

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.lang3.time;

/**
 * 

* StopWatch provides a convenient API for timings. *

* *

* To start the watch, call {@link #start()}. At this point you can: *

*
    *
  • {@link #split()} the watch to get the time whilst the watch continues in the background. {@link #unsplit()} will * remove the effect of the split. At this point, these three options are available again.
  • *
  • {@link #suspend()} the watch to pause it. {@link #resume()} allows the watch to continue. Any time between the * suspend and resume will not be counted in the total. At this point, these three options are available again.
  • *
  • {@link #stop()} the watch to complete the timing session.
  • *
* *

* It is intended that the output methods {@link #toString()} and {@link #getTime()} should only be called after stop, * split or suspend, however a suitable result will be returned at other points. *

* *

* NOTE: As from v2.1, the methods protect against inappropriate calls. Thus you cannot now call stop before start, * resume before suspend or unsplit before split. *

* *

* 1. split(), suspend(), or stop() cannot be invoked twice
* 2. unsplit() may only be called if the watch has been split()
* 3. resume() may only be called if the watch has been suspend()
* 4. start() cannot be called twice without calling reset() *

* *

This class is not thread-safe

* * @since 2.0 * @version $Id: StopWatch.java 1088899 2011-04-05 05:31:27Z bayard $ */ public class StopWatch { private static final long NANO_2_MILLIS = 1000000L; // running states private static final int STATE_UNSTARTED = 0; private static final int STATE_RUNNING = 1; private static final int STATE_STOPPED = 2; private static final int STATE_SUSPENDED = 3; // split state private static final int STATE_UNSPLIT = 10; private static final int STATE_SPLIT = 11; /** * The current running state of the StopWatch. */ private int runningState = STATE_UNSTARTED; /** * Whether the stopwatch has a split time recorded. */ private int splitState = STATE_UNSPLIT; /** * The start time. */ private long startTime; /** * The start time in Millis - nanoTime is only for elapsed time so we * need to also store the currentTimeMillis to maintain the old * getStartTime API. */ private long startTimeMillis; /** * The stop time. */ private long stopTime; /** *

* Constructor. *

*/ public StopWatch() { super(); } /** *

* Start the stopwatch. *

* *

* This method starts a new timing session, clearing any previous values. *

* * @throws IllegalStateException * if the StopWatch is already running. */ public void start() { if (this.runningState == STATE_STOPPED) { throw new IllegalStateException("Stopwatch must be reset before being restarted. "); } if (this.runningState != STATE_UNSTARTED) { throw new IllegalStateException("Stopwatch already started. "); } this.startTime = System.nanoTime(); this.startTimeMillis = System.currentTimeMillis(); this.runningState = STATE_RUNNING; } /** *

* Stop the stopwatch. *

* *

* This method ends a new timing session, allowing the time to be retrieved. *

* * @throws IllegalStateException * if the StopWatch is not running. */ public void stop() { if (this.runningState != STATE_RUNNING && this.runningState != STATE_SUSPENDED) { throw new IllegalStateException("Stopwatch is not running. "); } if (this.runningState == STATE_RUNNING) { this.stopTime = System.nanoTime(); } this.runningState = STATE_STOPPED; } /** *

* Resets the stopwatch. Stops it if need be. *

* *

* This method clears the internal values to allow the object to be reused. *

*/ public void reset() { this.runningState = STATE_UNSTARTED; this.splitState = STATE_UNSPLIT; } /** *

* Split the time. *

* *

* This method sets the stop time of the watch to allow a time to be extracted. The start time is unaffected, * enabling {@link #unsplit()} to continue the timing from the original start point. *

* * @throws IllegalStateException * if the StopWatch is not running. */ public void split() { if (this.runningState != STATE_RUNNING) { throw new IllegalStateException("Stopwatch is not running. "); } this.stopTime = System.nanoTime(); this.splitState = STATE_SPLIT; } /** *

* Remove a split. *

* *

* This method clears the stop time. The start time is unaffected, enabling timing from the original start point to * continue. *

* * @throws IllegalStateException * if the StopWatch has not been split. */ public void unsplit() { if (this.splitState != STATE_SPLIT) { throw new IllegalStateException("Stopwatch has not been split. "); } this.splitState = STATE_UNSPLIT; } /** *

* Suspend the stopwatch for later resumption. *

* *

* This method suspends the watch until it is resumed. The watch will not include time between the suspend and * resume calls in the total time. *

* * @throws IllegalStateException * if the StopWatch is not currently running. */ public void suspend() { if (this.runningState != STATE_RUNNING) { throw new IllegalStateException("Stopwatch must be running to suspend. "); } this.stopTime = System.nanoTime(); this.runningState = STATE_SUSPENDED; } /** *

* Resume the stopwatch after a suspend. *

* *

* This method resumes the watch after it was suspended. The watch will not include time between the suspend and * resume calls in the total time. *

* * @throws IllegalStateException * if the StopWatch has not been suspended. */ public void resume() { if (this.runningState != STATE_SUSPENDED) { throw new IllegalStateException("Stopwatch must be suspended to resume. "); } this.startTime += (System.nanoTime() - this.stopTime); this.runningState = STATE_RUNNING; } /** *

* Get the time on the stopwatch. *

* *

* This is either the time between the start and the moment this method is called, or the amount of time between * start and stop. *

* * @return the time in milliseconds */ public long getTime() { return getNanoTime() / NANO_2_MILLIS; } /** *

* Get the time on the stopwatch in nanoseconds. *

* *

* This is either the time between the start and the moment this method is called, or the amount of time between * start and stop. *

* * @return the time in nanoseconds * @since 3.0 */ public long getNanoTime() { if (this.runningState == STATE_STOPPED || this.runningState == STATE_SUSPENDED) { return this.stopTime - this.startTime; } else if (this.runningState == STATE_UNSTARTED) { return 0; } else if (this.runningState == STATE_RUNNING) { return System.nanoTime() - this.startTime; } throw new RuntimeException("Illegal running state has occured. "); } /** *

* Get the split time on the stopwatch. *

* *

* This is the time between start and latest split. *

* * @return the split time in milliseconds * * @throws IllegalStateException * if the StopWatch has not yet been split. * @since 2.1 */ public long getSplitTime() { return getSplitNanoTime() / NANO_2_MILLIS; } /** *

* Get the split time on the stopwatch in nanoseconds. *

* *

* This is the time between start and latest split. *

* * @return the split time in nanoseconds * * @throws IllegalStateException * if the StopWatch has not yet been split. * @since 3.0 */ public long getSplitNanoTime() { if (this.splitState != STATE_SPLIT) { throw new IllegalStateException("Stopwatch must be split to get the split time. "); } return this.stopTime - this.startTime; } /** * Returns the time this stopwatch was started. * * @return the time this stopwatch was started * @throws IllegalStateException * if this StopWatch has not been started * @since 2.4 */ public long getStartTime() { if (this.runningState == STATE_UNSTARTED) { throw new IllegalStateException("Stopwatch has not been started"); } // System.nanoTime is for elapsed time return this.startTimeMillis; } /** *

* Gets a summary of the time that the stopwatch recorded as a string. *

* *

* The format used is ISO8601-like, hours:minutes:seconds.milliseconds. *

* * @return the time as a String */ @Override public String toString() { return DurationFormatUtils.formatDurationHMS(getTime()); } /** *

* Gets a summary of the split time that the stopwatch recorded as a string. *

* *

* The format used is ISO8601-like, hours:minutes:seconds.milliseconds. *

* * @return the split time as a String * @since 2.1 */ public String toSplitString() { return DurationFormatUtils.formatDurationHMS(getSplitTime()); } }


 

 

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