无论使用哪种操作系统，用Java执行计划任务的最佳解决方案是什么？

这是我最终实现的：

public class AlarmManager {    public static final String ALARM_CLI_FORMAT = "startalarm:";    public static SupportedOS currentOS = SupportedOS.UNSUPPORTED_OS;    public enum SupportedOS {        UNSUPPORTED_OS,        MAC_OS,        WINDOWS,    }    public AlarmManager() {        final String osName = System.getProperty("os.name");        if (osName == null) { L.e("Unable to retrieve OS!");        } else if ("Mac OS X".equals(osName)) { currentOS = SupportedOS.MAC_OS;        } else if (osName.contains("Windows")) { currentOS = SupportedOS.WINDOWS;        } else { L.e("Unsupported OS: "+osName);        }    }        private String getAlarmName(final long alarmId) {        return new StringBuilder("My_Alarm_").append(alarmId).toString();    }        private String getAlarmCommandLine(final long alarmId) {        return new StringBuilder("javaws -open ").append(ALARM_CLI_FORMAT).append(alarmId).append(" ").append(G.JNLP_URL).toString();    }        public void createAlarm(final Calendar when) {        // Create alarm        // ... stuff here        final long alarmId = 42;        // Schedule alarm        String[] commandLine;        Process child;        final String alarmCL = getAlarmCommandLine(alarmId);        try { switch (currentOS) { case MAC_OS:     final String cron = new SimpleDateFormat("mm HH d M '*' ").format(when.getTime()) + alarmCL;     commandLine = new String[] {  "/bin/sh", "-c",  "crontab -l | (cat; echo "" + cron + "") | crontab"     };     child = Runtime.getRuntime().exec(commandLine);     break; case WINDOWS:     commandLine = new String[] {  "schtasks",  "/Create",  "/ST "+when.get(Calendar.HOUR_OF_DAY) + ":" + when.get(Calendar.MINUTE),  "/SC ONCE",  "/SD "+new SimpleDateFormat("dd/MM/yyyy").format(when.getTime()), // careful with locale here! dd/MM/yyyy or MM/dd/yyyy? I'm French! :)  "/TR ""+alarmCL+""",  "/TN ""+getAlarmName(alarmId)+""",  "/F",     };     L.d("create command: "+Util.join(commandLine, " "));     child = Runtime.getRuntime().exec(commandLine);     break; }        } catch (final IOException e) { L.e("Unable to schedule alarm #"+alarmId, e); return;        }        L.i("Created alarm #"+alarmId);    }        public void removeAlarm(final long alarmId) {        L.i("Removing alarm #"+alarmId);        String[] commandLine;        Process child;        try { switch (currentOS) { case MAC_OS:     commandLine = new String[] {  "/bin/sh", "-c",  "crontab -l | (grep -v ""+ALARM_CLI_FORMAT+"") | crontab"     };     child = Runtime.getRuntime().exec(commandLine);     break; case WINDOWS:     commandLine = new String[] {  "schtasks",  "/Delete",  "/TN ""+getAlarmName(alarmId)+""",  "/F",     };     child = Runtime.getRuntime().exec(commandLine);     break; }        } catch (final IOException e) { L.e("Unable to remove alarm #"+alarmId, e);        }    }    public void triggerAlarm(final long alarmId) {        // Do stuff        //...        L.i("Hi! I'm alarm #"+alarmId);        // Remove alarm        removeAlarm(alarmId);    }}

用法很简单。使用以下命令安排新警报：

final AlarmManager m = new AlarmManager();final Calendar cal = new GregorianCalendar();cal.add(Calendar.MINUTE, 1);m.createAlarm(cal);

触发这样的警报：

public static void main(final String[] args) {    if (args.length >= 2 && args[1] != null && args[1].contains(AlarmManager.ALARM_CLI_FORMAT)) {        try { final long alarmId = Long.parseLong(args[1].replace(AlarmManager.ALARM_CLI_FORMAT, "")); final AlarmManager m = new AlarmManager(); m.triggerAlarm(alarmId);        } catch (final NumberFormatException e) { L.e("Unable to parse alarm !", e);        }    }}

在Mac OS X.6和Windows
Vista上进行了测试。该类

L

System.out.println

G