JDK14/Java14源码在线阅读

/*
 * Copyright (c) 2011, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */

package sun.tools.jcmd;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

class Arguments {
    private boolean listProcesses = false;
    private boolean listCounters  = false;
    private boolean showUsage     = false;
    private String  command       = null;
    private String  processString = null;

    public boolean isListProcesses() { return listProcesses; }
    public boolean isListCounters() { return listCounters; }
    public boolean isShowUsage() { return showUsage; }
    public String getCommand() { return command; }
    public String getProcessString() { return processString; }

    public Arguments(String[] args) {
        if (args.length == 0 || args[0].equals("-l")) {
            listProcesses = true;
            /* list all processes */
            processString = "0";
            return;
        }

        if (args[0].equals("-?") ||
            args[0].equals("-h") ||
            args[0].equals("--help") ||
            // -help: legacy.
            args[0].equals("-help")) {
            showUsage = true;
            return;
        }

        processString = args[0];

        StringBuilder sb = new StringBuilder();
        for (int i = 1; i < args.length; i++) {
            if (args[i].equals("-f")) {
                if (args.length == i + 1) {
                    throw new IllegalArgumentException(
                        "No file specified for parameter -f");
                } else if (args.length == i + 2) {
                    try {
                        readCommandFile(args[i + 1]);
                    } catch(IOException e) {
                        throw new IllegalArgumentException(
                            "Could not read from file specified with -f option: "
                            + args[i + 1]);
                    }
                    return;
                } else {
                    throw new IllegalArgumentException(
                        "Options after -f are not allowed");
                }
            } else if (args[i].equals("PerfCounter.print")) {
                listCounters = true;
            } else {
                sb.append(args[i]).append(" ");
            }
        }

        if (listCounters != true && sb.length() == 0) {
            // Omitting the command shall cause the target VM to print out a list
            // of available commands.
            sb.append("help");
        }

        command = sb.toString().trim();
    }

    private void readCommandFile(String path) throws IOException {
        try (BufferedReader bf = new BufferedReader(new FileReader(path));) {
                StringBuilder sb = new StringBuilder();
                String s;
                while ((s = bf.readLine()) != null) {
                    sb.append(s).append("\n");
                }
                command = sb.toString();
            }
    }

    public static void usage() {
        System.out.println("Usage: jcmd <pid | main class> <command ...|PerfCounter.print|-f file>");
        System.out.println("   or: jcmd -l                                                    ");
        System.out.println("   or: jcmd -h                                                    ");
        System.out.println("                                                                  ");
        System.out.println("  command must be a valid jcmd command for the selected jvm.      ");
        System.out.println("  Use the command \"help\" to see which commands are available.   ");
        System.out.println("  If the pid is 0, commands will be sent to all Java processes.   ");
        System.out.println("  The main class argument will be used to match (either partially ");
        System.out.println("  or fully) the class used to start Java.                         ");

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