src/main/org/apache/tools/ant/util/ProcessUtil.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
 *
 *      https://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.lang.management.ManagementFactory;

/**
 * Process Utilities
 * @since Ant 1.9.4
 */
public class ProcessUtil {

    private ProcessUtil() {
    }

    /**
     * provide id of the current process
     * @param fallback fallback id
     * @return current process id
     */
    public static String getProcessId(final String fallback) {
        // Note: may fail in some JVM implementations
        // therefore fallback has to be provided

        // something like '<pid>@<hostname>', at least in SUN / Oracle JVMs
        final String jvmName = ManagementFactory.getRuntimeMXBean().getName();
        final int index = jvmName.indexOf('@');

        if (index < 1) {
            // part before '@' empty (index = 0) / '@' not found (index = -1)
            return fallback;
        }

        try {
            return Long.toString(Long.parseLong(jvmName.substring(0, index)));
        } catch (NumberFormatException e) {
            // ignore
        }
        return fallback;
    }

    public static void main(String[] args) {
        System.out.println(getProcessId("<PID>"));
        try {
            Thread.sleep(120000);
        } catch (Exception exc) {
            // ignore
        }
    }
}