看看ANT中怎么计算运行时间

原来每次运行ant，最后一行都会提示Total Time: 

所以觉得好奇，看看他是怎么计算的，其实跟我们平时计算的没有什么差别，

只是他用到了一些显示的处理，以下来源 ant 的源代码：

\main\org\apache\tools\ant\DefaultLogger.java

/*
 *  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.tools.ant;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintStream;
import java.io.StringReader;
import java.util.Date;
import java.text.DateFormat;

import org.apache.tools.ant.util.DateUtils;
import org.apache.tools.ant.util.StringUtils;
import org.apache.tools.ant.util.FileUtils;

/**
 * Writes build events to a PrintStream. Currently, it
 * only writes which targets are being executed, and
 * any messages that get logged.
 *
 */
public class DefaultLogger implements BuildLogger {
    /**
     * Size of left-hand column for right-justified task name.
     * @see #messageLogged(BuildEvent)
     */
    public static final int LEFT_COLUMN_SIZE = 12;

    // CheckStyle:VisibilityModifier OFF - bc
    /** PrintStream to write non-error messages to */
    protected PrintStream out;

    /** PrintStream to write error messages to */
    protected PrintStream err;

    /** Lowest level of message to write out */
    protected int msgOutputLevel = Project.MSG_ERR;

    /** Time of the start of the build */
    private long startTime = System.currentTimeMillis();

    // CheckStyle:ConstantNameCheck OFF - bc
    /** Line separator */
    protected static final String lSep = StringUtils.LINE_SEP;
    // CheckStyle:ConstantNameCheck ON

    /** Whether or not to use emacs-style output */
    protected boolean emacsMode = false;
    // CheckStyle:VisibilityModifier ON


    /**
     * Sole constructor.
     */
    public DefaultLogger() {
    }

    /**
     * Sets the highest level of message this logger should respond to.
     *
     * Only messages with a message level lower than or equal to the
     * given level should be written to the log.
     * <p>
     * Constants for the message levels are in the
     * {@link Project Project} class. The order of the levels, from least
     * to most verbose, is <code>MSG_ERR</code>, <code>MSG_WARN</code>,
     * <code>MSG_INFO</code>, <code>MSG_VERBOSE</code>,
     * <code>MSG_DEBUG</code>.
     * <p>
     * The default message level for DefaultLogger is Project.MSG_ERR.
     *
     * @param level the logging level for the logger.
     */
    public void setMessageOutputLevel(int level) {
        this.msgOutputLevel = level;
    }

    /**
     * Sets the output stream to which this logger is to send its output.
     *
     * @param output The output stream for the logger.
     *               Must not be <code>null</code>.
     */
    public void setOutputPrintStream(PrintStream output) {
        this.out = new PrintStream(output, true);
    }

    /**
     * Sets the output stream to which this logger is to send error messages.
     *
     * @param err The error stream for the logger.
     *            Must not be <code>null</code>.
     */
    public void setErrorPrintStream(PrintStream err) {
        this.err = new PrintStream(err, true);
    }

    /**
     * Sets this logger to produce emacs (and other editor) friendly output.
     *
     * @param emacsMode <code>true</code> if output is to be unadorned so that
     *                  emacs and other editors can parse files names, etc.
     */
    public void setEmacsMode(boolean emacsMode) {
        this.emacsMode = emacsMode;
    }

    /**
     * Responds to a build being started by just remembering the current time.
     *
     * @param event Ignored.
     */
    public void buildStarted(BuildEvent event) {
        startTime = System.currentTimeMillis();
    }

    static void throwableMessage(StringBuffer m, Throwable error, boolean verbose) {
        while (error instanceof BuildException) { // #43398
            Throwable cause = error.getCause();
            if (cause == null) {
                break;
            }
            String msg1 = error.toString();
            String msg2 = cause.toString();
            if (msg1.endsWith(msg2)) {
                m.append(msg1.substring(0, msg1.length() - msg2.length()));
                error = cause;
            } else {
                break;
            }
        }
        if (verbose || !(error instanceof BuildException)) {
            m.append(StringUtils.getStackTrace(error));
        } else {
            m.append(error).append(lSep);
        }
    }

    /**
     * Prints whether the build succeeded or failed,
     * any errors the occurred during the build, and
     * how long the build took.
     *
     * @param event An event with any relevant extra information.
     *              Must not be <code>null</code>.
     */
    public void buildFinished(BuildEvent event) {
        Throwable error = event.getException();
        StringBuffer message = new StringBuffer();
        if (error == null) {
            message.append(StringUtils.LINE_SEP);
            message.append(getBuildSuccessfulMessage());
        } else {
            message.append(StringUtils.LINE_SEP);
            message.append(getBuildFailedMessage());
            message.append(StringUtils.LINE_SEP);
            throwableMessage(message, error, Project.MSG_VERBOSE <= msgOutputLevel);
        }
        message.append(StringUtils.LINE_SEP);
        message.append("Total time: ");
        message.append(formatTime(System.currentTimeMillis() - startTime));

        String msg = message.toString();
        if (error == null) {
            printMessage(msg, out, Project.MSG_VERBOSE);
        } else {
            printMessage(msg, err, Project.MSG_ERR);
        }
        log(msg);
    }

    /**
     * This is an override point: the message that indicates whether a build failed.
     * Subclasses can change/enhance the message.
     * @return The classic "BUILD FAILED"
     */
    protected String getBuildFailedMessage() {
        return "BUILD FAILED";
    }

    /**
     * This is an override point: the message that indicates that a build succeeded.
     * Subclasses can change/enhance the message.
     * @return The classic "BUILD SUCCESSFUL"
     */
    protected String getBuildSuccessfulMessage() {
        return "BUILD SUCCESSFUL";
    }

    /**
     * Logs a message to say that the target has started if this
     * logger allows information-level messages.
     *
     * @param event An event with any relevant extra information.
     *              Must not be <code>null</code>.
      */
    public void targetStarted(BuildEvent event) {
        if (Project.MSG_INFO <= msgOutputLevel
            && !event.getTarget().getName().equals("")) {
            String msg = StringUtils.LINE_SEP
                + event.getTarget().getName() + ":";
            printMessage(msg, out, event.getPriority());
            log(msg);
        }
    }

    /**
     * No-op implementation.
     *
     * @param event Ignored.
     */
    public void targetFinished(BuildEvent event) {
    }

    /**
     * No-op implementation.
     *
     * @param event Ignored.
     */
    public void taskStarted(BuildEvent event) {
    }

    /**
     * No-op implementation.
     *
     * @param event Ignored.
     */
    public void taskFinished(BuildEvent event) {
    }

    /**
     * Logs a message, if the priority is suitable.
     * In non-emacs mode, task level messages are prefixed by the
     * task name which is right-justified.
     *
     * @param event A BuildEvent containing message information.
     *              Must not be <code>null</code>.
     */
    public void messageLogged(BuildEvent event) {
        int priority = event.getPriority();
        // Filter out messages based on priority
        if (priority <= msgOutputLevel) {

            StringBuffer message = new StringBuffer();
            if (event.getTask() != null && !emacsMode) {
                // Print out the name of the task if we're in one
                String name = event.getTask().getTaskName();
                String label = "[" + name + "] ";
                int size = LEFT_COLUMN_SIZE - label.length();
                StringBuffer tmp = new StringBuffer();
                for (int i = 0; i < size; i++) {
                    tmp.append(" ");
                }
                tmp.append(label);
                label = tmp.toString();

                BufferedReader r = null;
                try {
                    r = new BufferedReader(
                            new StringReader(event.getMessage()));
                    String line = r.readLine();
                    boolean first = true;
                    do {
                        if (first) {
                            if (line == null) {
                                message.append(label);
                                break;
                            }
                        } else {
                            message.append(StringUtils.LINE_SEP);
                        }
                        first = false;
                        message.append(label).append(line);
                        line = r.readLine();
                    } while (line != null);
                } catch (IOException e) {
                    // shouldn't be possible
                    message.append(label).append(event.getMessage());
                } finally {
                    if (r != null) {
                        FileUtils.close(r);
                    }
                }

            } else {
                //emacs mode or there is no task
                message.append(event.getMessage());
            }
            Throwable ex = event.getException();
            if (Project.MSG_DEBUG <= msgOutputLevel && ex != null) {
                    message.append(StringUtils.getStackTrace(ex));
            }

            String msg = message.toString();
            if (priority != Project.MSG_ERR) {
                printMessage(msg, out, priority);
            } else {
                printMessage(msg, err, priority);
            }
            log(msg);
        }
    }

    /**
     * Convenience method to format a specified length of time.
     *
     * @param millis Length of time to format, in milliseconds.
     *
     * @return the time as a formatted string.
     *
     * @see DateUtils#formatElapsedTime(long)
     */
    protected static String formatTime(final long millis) {
        return DateUtils.formatElapsedTime(millis);
    }

    /**
     * Prints a message to a PrintStream.
     *
     * @param message  The message to print.
     *                 Should not be <code>null</code>.
     * @param stream   A PrintStream to print the message to.
     *                 Must not be <code>null</code>.
     * @param priority The priority of the message.
     *                 (Ignored in this implementation.)
     */
    protected void printMessage(final String message,
                                final PrintStream stream,
                                final int priority) {
        stream.println(message);
    }

    /**
     * Empty implementation which allows subclasses to receive the
     * same output that is generated here.
     *
     * @param message Message being logged. Should not be <code>null</code>.
     */
    protected void log(String message) {
    }

    /**
     * Get the current time.
     * @return the current time as a formatted string.
     * @since Ant1.7.1
     */
    protected String getTimestamp() {
        Date date = new Date(System.currentTimeMillis());
        DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT);
        String finishTime = formatter.format(date);
        return finishTime;
    }

    /**
     * Get the project name or null
     * @param event the event
     * @return the project that raised this event
     * @since Ant1.7.1
     */
    protected String extractProjectName(BuildEvent event) {
        Project project = event.getProject();
        return (project != null) ? project.getName() : null;
    }
}

另外一个工具类的文件如下：

\main\org\apache\tools\ant\util\DateUtils.java

/*
 *  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.tools.ant.util;

import java.text.ChoiceFormat;
import java.text.DateFormat;
import java.text.MessageFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;

/**
 * Helper methods to deal with date/time formatting with a specific
 * defined format (<a href="http://www.w3.org/TR/NOTE-datetime">ISO8601</a>)
 * or a plurialization correct elapsed time in minutes and seconds.
 *
 * @since Ant 1.5
 *
 */
public final class DateUtils {

    private static final int ONE_SECOND = 1000;
    private static final int ONE_MINUTE = 60;
    private static final int ONE_HOUR = 60;
    private static final int TEN = 10;
    /**
     * ISO8601-like pattern for date-time. It does not support timezone.
     *  <tt>yyyy-MM-ddTHH:mm:ss</tt>
     */
    public static final String ISO8601_DATETIME_PATTERN
            = "yyyy-MM-dd'T'HH:mm:ss";

    /**
     * ISO8601-like pattern for date. <tt>yyyy-MM-dd</tt>
     */
    public static final String ISO8601_DATE_PATTERN
            = "yyyy-MM-dd";

    /**
     * ISO8601-like pattern for time.  <tt>HH:mm:ss</tt>
     */
    public static final String ISO8601_TIME_PATTERN
            = "HH:mm:ss";

    /**
     * Format used for SMTP (and probably other) Date headers.
     * @deprecated DateFormat is not thread safe, and we cannot guarantee that
     * some other code is using the format in parallel.
     * Deprecated since ant 1.8
     */
    public static final DateFormat DATE_HEADER_FORMAT
        = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss ", Locale.US);

    private static final DateFormat DATE_HEADER_FORMAT_INT
    = new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss ", Locale.US);
    
    
// code from Magesh moved from DefaultLogger and slightly modified
    private static final MessageFormat MINUTE_SECONDS
            = new MessageFormat("{0}{1}");

    private static final double[] LIMITS = {0, 1, 2};

    private static final String[] MINUTES_PART = {"", "1 minute ", "{0,number,###############} minutes "};

    private static final String[] SECONDS_PART = {"0 seconds", "1 second", "{1,number} seconds"};

    private static final ChoiceFormat MINUTES_FORMAT =
            new ChoiceFormat(LIMITS, MINUTES_PART);

    private static final ChoiceFormat SECONDS_FORMAT =
            new ChoiceFormat(LIMITS, SECONDS_PART);

    static {
        MINUTE_SECONDS.setFormat(0, MINUTES_FORMAT);
        MINUTE_SECONDS.setFormat(1, SECONDS_FORMAT);
    }

    /** private constructor */
    private DateUtils() {
    }


    /**
     * Format a date/time into a specific pattern.
     * @param date the date to format expressed in milliseconds.
     * @param pattern the pattern to use to format the date.
     * @return the formatted date.
     */
    public static String format(long date, String pattern) {
        return format(new Date(date), pattern);
    }


    /**
     * Format a date/time into a specific pattern.
     * @param date the date to format expressed in milliseconds.
     * @param pattern the pattern to use to format the date.
     * @return the formatted date.
     */
    public static String format(Date date, String pattern) {
        DateFormat df = createDateFormat(pattern);
        return df.format(date);
    }


    /**
     * Format an elapsed time into a plurialization correct string.
     * It is limited only to report elapsed time in minutes and
     * seconds and has the following behavior.
     * <ul>
     * <li>minutes are not displayed when 0. (ie: "45 seconds")</li>
     * <li>seconds are always displayed in plural form (ie "0 seconds" or
     * "10 seconds") except for 1 (ie "1 second")</li>
     * </ul>
     * @param millis the elapsed time to report in milliseconds.
     * @return the formatted text in minutes/seconds.
     */
    public static String formatElapsedTime(long millis) {
        long seconds = millis / ONE_SECOND;
        long minutes = seconds / ONE_MINUTE;
        Object[] args = {new Long(minutes), new Long(seconds % ONE_MINUTE)};
        return MINUTE_SECONDS.format(args);
    }

    /**
     * return a lenient date format set to GMT time zone.
     * @param pattern the pattern used for date/time formatting.
     * @return the configured format for this pattern.
     */
    private static DateFormat createDateFormat(String pattern) {
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        TimeZone gmt = TimeZone.getTimeZone("GMT");
        sdf.setTimeZone(gmt);
        sdf.setLenient(true);
        return sdf;
    }

    /**
     * Calculate the phase of the moon for a given date.
     *
     * <p>Code heavily influenced by hacklib.c in <a
     * href="http://www.nethack.org/">Nethack</a></p>
     *
     * <p>The Algorithm:
     *
     * <pre>
     * moon period = 29.53058 days ~= 30, year = 365.2422 days
     *
     * days moon phase advances on first day of year compared to preceding year
     *  = 365.2422 - 12*29.53058 ~= 11
     *
     * years in Metonic cycle (time until same phases fall on the same days of
     *  the month) = 18.6 ~= 19
     *
     * moon phase on first day of year (epact) ~= (11*(year%19) + 18) % 30
     *  (18 as initial condition for 1900)
     *
     * current phase in days = first day phase + days elapsed in year
     *
     * 6 moons ~= 177 days
     * 177 ~= 8 reported phases * 22
     * + 11/22 for rounding
     * </pre>
     *
     * @param cal the calander.
     *
     * @return The phase of the moon as a number between 0 and 7 with
     *         0 meaning new moon and 4 meaning full moon.
     *
     * @since 1.2, Ant 1.5
     */
    public static int getPhaseOfMoon(Calendar cal) {
        // CheckStyle:MagicNumber OFF
        int dayOfTheYear = cal.get(Calendar.DAY_OF_YEAR);
        int yearInMetonicCycle = ((cal.get(Calendar.YEAR) - 1900) % 19) + 1;
        int epact = (11 * yearInMetonicCycle + 18) % 30;
        if ((epact == 25 && yearInMetonicCycle > 11) || epact == 24) {
            epact++;
        }
        return (((((dayOfTheYear + epact) * 6) + 11) % 177) / 22) & 7;
        // CheckStyle:MagicNumber ON
    }

    /**
     * Returns the current Date in a format suitable for a SMTP date
     * header.
     * @return the current date.
     * @since Ant 1.5.2
     */
    public static String getDateForHeader() {
        Calendar cal = Calendar.getInstance();
        TimeZone tz = cal.getTimeZone();
        int offset = tz.getOffset(cal.get(Calendar.ERA),
                                  cal.get(Calendar.YEAR),
                                  cal.get(Calendar.MONTH),
                                  cal.get(Calendar.DAY_OF_MONTH),
                                  cal.get(Calendar.DAY_OF_WEEK),
                                  cal.get(Calendar.MILLISECOND));
        StringBuffer tzMarker = new StringBuffer(offset < 0 ? "-" : "+");
        offset = Math.abs(offset);
        int hours = offset / (ONE_HOUR * ONE_MINUTE * ONE_SECOND);
        int minutes = offset / (ONE_MINUTE * ONE_SECOND) - ONE_HOUR * hours;
        if (hours < TEN) {
            tzMarker.append("0");
        }
        tzMarker.append(hours);
        if (minutes < TEN) {
            tzMarker.append("0");
        }
        tzMarker.append(minutes);
        synchronized (DATE_HEADER_FORMAT_INT) {
            return DATE_HEADER_FORMAT_INT.format(cal.getTime()) + tzMarker.toString();
        }
    }

    /**
     * Parses the string in a format suitable for a SMTP date header.
     *
     * @param datestr string to be parsed
     *
     * @return a java.util.Date object as parsed by the format.
     * @exception ParseException if the supplied string cannot be parsed by
     * this pattern.
     * @since Ant 1.8.0
     */
    public static Date parseDateFromHeader(String datestr) throws ParseException {
        synchronized (DATE_HEADER_FORMAT_INT) {
            return DATE_HEADER_FORMAT_INT.parse(datestr);
        }
    }

    /**
     * Parse a string as a datetime using the ISO8601_DATETIME format which is
     * <code>yyyy-MM-dd'T'HH:mm:ss</code>
     *
     * @param datestr string to be parsed
     *
     * @return a java.util.Date object as parsed by the format.
     * @exception ParseException if the supplied string cannot be parsed by
     * this pattern.
     * @since Ant 1.6
     */
    public static Date parseIso8601DateTime(String datestr)
        throws ParseException {
        return new SimpleDateFormat(ISO8601_DATETIME_PATTERN).parse(datestr);
    }

    /**
     * Parse a string as a date using the ISO8601_DATE format which is
     * <code>yyyy-MM-dd</code>
     *
     * @param datestr string to be parsed
     *
     * @return a java.util.Date object as parsed by the format.
     * @exception ParseException if the supplied string cannot be parsed by
     * this pattern.
     * @since Ant 1.6
     */
    public static Date parseIso8601Date(String datestr) throws ParseException {
        return new SimpleDateFormat(ISO8601_DATE_PATTERN).parse(datestr);
    }

    /**
     * Parse a string as a date using the either the ISO8601_DATETIME
     * or ISO8601_DATE formats.
     *
     * @param datestr string to be parsed
     *
     * @return a java.util.Date object as parsed by the formats.
     * @exception ParseException if the supplied string cannot be parsed by
     * either of these patterns.
     * @since Ant 1.6
     */
    public static Date parseIso8601DateTimeOrDate(String datestr)
        throws ParseException {
        try {
            return parseIso8601DateTime(datestr);
        } catch (ParseException px) {
            return parseIso8601Date(datestr);
        }
    }
}

我根据这两个类，修改为我自己的程序执行时间显示为：

package com.xjh.util;

import java.text.ChoiceFormat;
import java.text.MessageFormat;

public class TotalTime {
	
	private static final int ONE_SECOND = 1000;
	private static final int ONE_MINUTE = 60;
	
	private static final double[] LIMITS = {0, 1, 2};
	
	private static final String[] MINUTES_PART = {"", "1 minute", "{0,number,###############} minutes"};
	
	private static final String[] SECONDS_PART = {"0 seconds", "1 second", "{1,number} seconds"};
	
	private static final ChoiceFormat MINUTES_FORMAT = new ChoiceFormat(LIMITS, MINUTES_PART);
	
	private static final ChoiceFormat SECONDS_FORMAT = new ChoiceFormat(LIMITS, SECONDS_PART);
		
	private static final MessageFormat MINUTE_SECONDS = new MessageFormat("{0} {1}");
	
	static {
		MINUTE_SECONDS.setFormat(0, MINUTES_FORMAT);
		MINUTE_SECONDS.setFormat(1, SECONDS_FORMAT);
	}
	
	public static void main(String[] args) {
	
		long startTime = System.currentTimeMillis();
		
		long sum = 0;
		for (int i = 1; i < Integer.MAX_VALUE; i++) {
			sum = sum + i;
		}
		
		System.out.println("sum is " + sum);
		System.out.println("Total time: " + formatTime(System.currentTimeMillis() - startTime));
//		System.out.println(TotalTime.formatTime(59000));
		
	}
	
	public static String formatTime(final long millis) {
//		long seconds = 0;
//		long minutes = 0;
		long seconds = millis / ONE_SECOND; // 得到秒
		long minutes = seconds / ONE_MINUTE; // 得到分钟
		Object[] args = {new Long(minutes), new Long(seconds % ONE_MINUTE)};
		return MINUTE_SECONDS.format(args);
	}
	
}