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Java example source code file (Main.java)

This example Java source code file (Main.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, assertionerror, batch, batchenvironment, class, file, generator, javadoc, jrmpgenerator, list, main, object, printstream, printwriter, reflection, string, util

The Main.java Java example source code

/*
 * Copyright (c) 2003, 2012, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.rmi.rmic.newrmic;

import com.sun.javadoc.ClassDoc;
import com.sun.javadoc.RootDoc;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import sun.rmi.rmic.newrmic.jrmp.JrmpGenerator;
import sun.tools.util.CommandLine;

/**
 * The rmic front end.  This class contains the "main" method for rmic
 * command line invocation.
 *
 * A Main instance contains the stream to output error messages and
 * other diagnostics to.
 *
 * An rmic compilation batch (for example, one rmic command line
 * invocation) is executed by invoking the "compile" method of a Main
 * instance.
 *
 * WARNING: The contents of this source file are not part of any
 * supported API.  Code that depends on them does so at its own risk:
 * they are subject to change or removal without notice.
 *
 * NOTE: If and when there is a J2SE API for invoking SDK tools, this
 * class should be updated to support that API.
 *
 * NOTE: This class is the front end for a "new" rmic implementation,
 * which uses javadoc and the doclet API for reading class files and
 * javac for compiling generated source files.  This implementation is
 * incomplete: it lacks any CORBA-based back end implementations, and
 * thus the command line options "-idl", "-iiop", and their related
 * options are not yet supported.  The front end for the "old",
 * oldjavac-based rmic implementation is sun.rmi.rmic.Main.
 *
 * @author Peter Jones
 **/
public class Main {

    /*
     * Implementation note:
     *
     * In order to use the doclet API to read class files, much of
     * this implementation of rmic executes as a doclet within an
     * invocation of javadoc.  This class is used as the doclet class
     * for such javadoc invocations, via its static "start" and
     * "optionLength" methods.  There is one javadoc invocation per
     * rmic compilation batch.
     *
     * The only guaranteed way to pass data to a doclet through a
     * javadoc invocation is through doclet-specific options on the
     * javadoc "command line".  Rather than passing numerous pieces of
     * individual data in string form as javadoc options, we use a
     * single doclet-specific option ("-batchID") to pass a numeric
     * identifier that uniquely identifies the rmic compilation batch
     * that the javadoc invocation is for, and that identifier can
     * then be used as a key in a global table to retrieve an object
     * containing all of batch-specific data (rmic command line
     * arguments, etc.).
     */

    /** guards "batchCount" */
    private static final Object batchCountLock = new Object();

    /** number of batches run; used to generated batch IDs */
    private static long batchCount = 0;

    /** maps batch ID to batch data */
    private static final Map<Long,Batch> batchTable =
        Collections.synchronizedMap(new HashMap<Long,Batch>());

    /** stream to output error messages and other diagnostics to */
    private final PrintStream out;

    /** name of this program, to use in error messages */
    private final String program;

    /**
     * Command line entry point.
     **/
    public static void main(String[] args) {
        Main rmic = new Main(System.err, "rmic");
        System.exit(rmic.compile(args) ? 0 : 1);
    }

    /**
     * Creates a Main instance that writes output to the specified
     * stream.  The specified program name is used in error messages.
     **/
    public Main(OutputStream out, String program) {
        this.out = out instanceof PrintStream ?
            (PrintStream) out : new PrintStream(out);
        this.program = program;
    }

    /**
     * Compiles a batch of input classes, as given by the specified
     * command line arguments.  Protocol-specific generators are
     * determined by the choice options on the command line.  Returns
     * true if successful, or false if an error occurred.
     *
     * NOTE: This method is retained for transitional consistency with
     * previous implementations.
     **/
    public boolean compile(String[] args) {
        long startTime = System.currentTimeMillis();

        long batchID;
        synchronized (batchCountLock) {
            batchID = batchCount++;     // assign batch ID
        }

        // process command line
        Batch batch = parseArgs(args);
        if (batch == null) {
            return false;               // terminate if error occurred
        }

        /*
         * With the batch data retrievable in the global table, run
         * javadoc to continue the rest of the batch's compliation as
         * a doclet.
         */
        boolean status;
        try {
            batchTable.put(batchID, batch);
            status = invokeJavadoc(batch, batchID);
        } finally {
            batchTable.remove(batchID);
        }

        if (batch.verbose) {
            long deltaTime = System.currentTimeMillis() - startTime;
            output(Resources.getText("rmic.done_in",
                                     Long.toString(deltaTime)));
        }

        return status;
    }

    /**
     * Prints the specified string to the output stream of this Main
     * instance.
     **/
    public void output(String msg) {
        out.println(msg);
    }

    /**
     * Prints an error message to the output stream of this Main
     * instance.  The first argument is used as a key in rmic's
     * resource bundle, and the rest of the arguments are used as
     * arguments in the formatting of the resource string.
     **/
    public void error(String msg, String... args) {
        output(Resources.getText(msg, args));
    }

    /**
     * Prints rmic's usage message to the output stream of this Main
     * instance.
     *
     * This method is public so that it can be used by the "parseArgs"
     * methods of Generator implementations.
     **/
    public void usage() {
        error("rmic.usage", program);
    }

    /**
     * Processes rmic command line arguments.  Returns a Batch object
     * representing the command line arguments if successful, or null
     * if an error occurred.  Processed elements of the args array are
     * set to null.
     **/
    private Batch parseArgs(String[] args) {
        Batch batch = new Batch();

        /*
         * Pre-process command line for @file arguments.
         */
        try {
            args = CommandLine.parse(args);
        } catch (FileNotFoundException e) {
            error("rmic.cant.read", e.getMessage());
            return null;
        } catch (IOException e) {
            e.printStackTrace(out);
            return null;
        }

        for (int i = 0; i < args.length; i++) {

            if (args[i] == null) {
                // already processed by a generator
                continue;

            } else if (args[i].equals("-Xnew")) {
                // we're already using the "new" implementation
                args[i] = null;

            } else if (args[i].equals("-show")) {
                // obselete: fail
                error("rmic.option.unsupported", args[i]);
                usage();
                return null;

            } else if (args[i].equals("-O")) {
                // obselete: warn but tolerate
                error("rmic.option.unsupported", args[i]);
                args[i] = null;

            } else if (args[i].equals("-debug")) {
                // obselete: warn but tolerate
                error("rmic.option.unsupported", args[i]);
                args[i] = null;

            } else if (args[i].equals("-depend")) {
                // obselete: warn but tolerate
                // REMIND: should this fail instead?
                error("rmic.option.unsupported", args[i]);
                args[i] = null;

            } else if (args[i].equals("-keep") ||
                       args[i].equals("-keepgenerated"))
            {
                batch.keepGenerated = true;
                args[i] = null;

            } else if (args[i].equals("-g")) {
                batch.debug = true;
                args[i] = null;

            } else if (args[i].equals("-nowarn")) {
                batch.noWarn = true;
                args[i] = null;

            } else if (args[i].equals("-nowrite")) {
                batch.noWrite = true;
                args[i] = null;

            } else if (args[i].equals("-verbose")) {
                batch.verbose = true;
                args[i] = null;

            } else if (args[i].equals("-Xnocompile")) {
                batch.noCompile = true;
                batch.keepGenerated = true;
                args[i] = null;

            } else if (args[i].equals("-bootclasspath")) {
                if ((i + 1) >= args.length) {
                    error("rmic.option.requires.argument", args[i]);
                    usage();
                    return null;
                }
                if (batch.bootClassPath != null) {
                    error("rmic.option.already.seen", args[i]);
                    usage();
                    return null;
                }
                args[i] = null;
                batch.bootClassPath = args[++i];
                assert batch.bootClassPath != null;
                args[i] = null;

            } else if (args[i].equals("-extdirs")) {
                if ((i + 1) >= args.length) {
                    error("rmic.option.requires.argument", args[i]);
                    usage();
                    return null;
                }
                if (batch.extDirs != null) {
                    error("rmic.option.already.seen", args[i]);
                    usage();
                    return null;
                }
                args[i] = null;
                batch.extDirs = args[++i];
                assert batch.extDirs != null;
                args[i] = null;

            } else if (args[i].equals("-classpath")) {
                if ((i + 1) >= args.length) {
                    error("rmic.option.requires.argument", args[i]);
                    usage();
                    return null;
                }
                if (batch.classPath != null) {
                    error("rmic.option.already.seen", args[i]);
                    usage();
                    return null;
                }
                args[i] = null;
                batch.classPath = args[++i];
                assert batch.classPath != null;
                args[i] = null;

            } else if (args[i].equals("-d")) {
                if ((i + 1) >= args.length) {
                    error("rmic.option.requires.argument", args[i]);
                    usage();
                    return null;
                }
                if (batch.destDir != null) {
                    error("rmic.option.already.seen", args[i]);
                    usage();
                    return null;
                }
                args[i] = null;
                batch.destDir = new File(args[++i]);
                assert batch.destDir != null;
                args[i] = null;
                if (!batch.destDir.exists()) {
                    error("rmic.no.such.directory", batch.destDir.getPath());
                    usage();
                    return null;
                }

            } else if (args[i].equals("-v1.1") ||
                       args[i].equals("-vcompat") ||
                       args[i].equals("-v1.2"))
            {
                Generator gen = new JrmpGenerator();
                batch.generators.add(gen);
                // JrmpGenerator only requires base BatchEnvironment class
                if (!gen.parseArgs(args, this)) {
                    return null;
                }

            } else if (args[i].equalsIgnoreCase("-iiop")) {
                error("rmic.option.unimplemented", args[i]);
                return null;

                // Generator gen = new IiopGenerator();
                // batch.generators.add(gen);
                // if (!batch.envClass.isAssignableFrom(gen.envClass())) {
                //   error("rmic.cannot.use.both",
                //         batch.envClass.getName(), gen.envClass().getName());
                //   return null;
                // }
                // batch.envClass = gen.envClass();
                // if (!gen.parseArgs(args, this)) {
                //   return null;
                // }

            } else if (args[i].equalsIgnoreCase("-idl")) {
                error("rmic.option.unimplemented", args[i]);
                return null;

                // see implementation sketch above

            } else if (args[i].equalsIgnoreCase("-xprint")) {
                error("rmic.option.unimplemented", args[i]);
                return null;

                // see implementation sketch above
            }
        }

        /*
         * At this point, all that remains non-null in the args
         * array are input class names or illegal options.
         */
        for (int i = 0; i < args.length; i++) {
            if (args[i] != null) {
                if (args[i].startsWith("-")) {
                    error("rmic.no.such.option", args[i]);
                    usage();
                    return null;
                } else {
                    batch.classes.add(args[i]);
                }
            }
        }
        if (batch.classes.isEmpty()) {
            usage();
            return null;
        }

        /*
         * If options did not specify at least one protocol-specific
         * generator, then JRMP is the default.
         */
        if (batch.generators.isEmpty()) {
            batch.generators.add(new JrmpGenerator());
        }
        return batch;
    }

    /**
     * Doclet class entry point.
     **/
    public static boolean start(RootDoc rootDoc) {

        /*
         * Find batch ID among javadoc options, and retrieve
         * corresponding batch data from global table.
         */
        long batchID = -1;
        for (String[] option : rootDoc.options()) {
            if (option[0].equals("-batchID")) {
                try {
                    batchID = Long.parseLong(option[1]);
                } catch (NumberFormatException e) {
                    throw new AssertionError(e);
                }
            }
        }
        Batch batch = batchTable.get(batchID);
        assert batch != null;

        /*
         * Construct batch environment using class agreed upon by
         * generator implementations.
         */
        BatchEnvironment env;
        try {
            Constructor<? extends BatchEnvironment> cons =
                batch.envClass.getConstructor(new Class<?>[] { RootDoc.class });
            env = cons.newInstance(rootDoc);
        } catch (NoSuchMethodException e) {
            throw new AssertionError(e);
        } catch (IllegalAccessException e) {
            throw new AssertionError(e);
        } catch (InstantiationException e) {
            throw new AssertionError(e);
        } catch (InvocationTargetException e) {
            throw new AssertionError(e);
        }

        env.setVerbose(batch.verbose);

        /*
         * Determine the destination directory (the top of the package
         * hierarchy) for the output of this batch; if no destination
         * directory was specified on the command line, then the
         * default is the current working directory.
         */
        File destDir = batch.destDir;
        if (destDir == null) {
            destDir = new File(System.getProperty("user.dir"));
        }

        /*
         * Run each input class through each generator.
         */
        for (String inputClassName : batch.classes) {
            ClassDoc inputClass = rootDoc.classNamed(inputClassName);
            try {
                for (Generator gen : batch.generators) {
                    gen.generate(env, inputClass, destDir);
                }
            } catch (NullPointerException e) {
                /*
                 * We assume that this means that some class that was
                 * needed (perhaps even a bootstrap class) was not
                 * found, and that javadoc has already reported this
                 * as an error.  There is nothing for us to do here
                 * but try to continue with the next input class.
                 *
                 * REMIND: More explicit error checking throughout
                 * would be preferable, however.
                 */
            }
        }

        /*
         * Compile any generated source files, if configured to do so.
         */
        boolean status = true;
        List<File> generatedFiles = env.generatedFiles();
        if (!batch.noCompile && !batch.noWrite && !generatedFiles.isEmpty()) {
            status = batch.enclosingMain().invokeJavac(batch, generatedFiles);
        }

        /*
         * Delete any generated source files, if configured to do so.
         */
        if (!batch.keepGenerated) {
            for (File file : generatedFiles) {
                file.delete();
            }
        }

        return status;
    }

    /**
     * Doclet class method that indicates that this doclet class
     * recognizes (only) the "-batchID" option on the javadoc command
     * line, and that the "-batchID" option comprises two arguments on
     * the javadoc command line.
     **/
    public static int optionLength(String option) {
        if (option.equals("-batchID")) {
            return 2;
        } else {
            return 0;
        }
    }

    /**
     * Runs the javadoc tool to invoke this class as a doclet, passing
     * command line options derived from the specified batch data and
     * indicating the specified batch ID.
     *
     * NOTE: This method currently uses a J2SE-internal API to run
     * javadoc.  If and when there is a J2SE API for invoking SDK
     * tools, this method should be updated to use that API instead.
     **/
    private boolean invokeJavadoc(Batch batch, long batchID) {
        List<String> javadocArgs = new ArrayList();

        // include all types, regardless of language-level access
        javadocArgs.add("-private");

        // inputs are class names, not source files
        javadocArgs.add("-Xclasses");

        // reproduce relevant options from rmic invocation
        if (batch.verbose) {
            javadocArgs.add("-verbose");
        }
        if (batch.bootClassPath != null) {
            javadocArgs.add("-bootclasspath");
            javadocArgs.add(batch.bootClassPath);
        }
        if (batch.extDirs != null) {
            javadocArgs.add("-extdirs");
            javadocArgs.add(batch.extDirs);
        }
        if (batch.classPath != null) {
            javadocArgs.add("-classpath");
            javadocArgs.add(batch.classPath);
        }

        // specify batch ID
        javadocArgs.add("-batchID");
        javadocArgs.add(Long.toString(batchID));

        /*
         * Run javadoc on union of rmic input classes and all
         * generators' bootstrap classes, so that they will all be
         * available to the doclet code.
         */
        Set<String> classNames = new HashSet();
        for (Generator gen : batch.generators) {
            classNames.addAll(gen.bootstrapClassNames());
        }
        classNames.addAll(batch.classes);
        for (String s : classNames) {
            javadocArgs.add(s);
        }

        // run javadoc with our program name and output stream
        int status = com.sun.tools.javadoc.Main.execute(
            program,
            new PrintWriter(out, true),
            new PrintWriter(out, true),
            new PrintWriter(out, true),
            this.getClass().getName(),          // doclet class is this class
            javadocArgs.toArray(new String[javadocArgs.size()]));
        return status == 0;
    }

    /**
     * Runs the javac tool to compile the specified source files,
     * passing command line options derived from the specified batch
     * data.
     *
     * NOTE: This method currently uses a J2SE-internal API to run
     * javac.  If and when there is a J2SE API for invoking SDK tools,
     * this method should be updated to use that API instead.
     **/
    private boolean invokeJavac(Batch batch, List<File> files) {
        List<String> javacArgs = new ArrayList();

        // rmic never wants to display javac warnings
        javacArgs.add("-nowarn");

        // reproduce relevant options from rmic invocation
        if (batch.debug) {
            javacArgs.add("-g");
        }
        if (batch.verbose) {
            javacArgs.add("-verbose");
        }
        if (batch.bootClassPath != null) {
            javacArgs.add("-bootclasspath");
            javacArgs.add(batch.bootClassPath);
        }
        if (batch.extDirs != null) {
            javacArgs.add("-extdirs");
            javacArgs.add(batch.extDirs);
        }
        if (batch.classPath != null) {
            javacArgs.add("-classpath");
            javacArgs.add(batch.classPath);
        }

        /*
         * For now, rmic still always produces class files that have a
         * class file format version compatible with JDK 1.1.
         */
        javacArgs.add("-source");
        javacArgs.add("1.3");
        javacArgs.add("-target");
        javacArgs.add("1.1");

        // add source files to compile
        for (File file : files) {
            javacArgs.add(file.getPath());
        }

        // run javac with our output stream
        int status = com.sun.tools.javac.Main.compile(
            javacArgs.toArray(new String[javacArgs.size()]),
            new PrintWriter(out, true));
        return status == 0;
    }

    /**
     * The data for an rmic compliation batch: the processed command
     * line arguments.
     **/
    private class Batch {
        boolean keepGenerated = false;  // -keep or -keepgenerated
        boolean debug = false;          // -g
        boolean noWarn = false;         // -nowarn
        boolean noWrite = false;        // -nowrite
        boolean verbose = false;        // -verbose
        boolean noCompile = false;      // -Xnocompile
        String bootClassPath = null;    // -bootclasspath
        String extDirs = null;          // -extdirs
        String classPath = null;        // -classpath
        File destDir = null;            // -d
        List<Generator> generators = new ArrayList();
        Class<? extends BatchEnvironment> envClass = BatchEnvironment.class;
        List<String> classes = new ArrayList();

        Batch() { }

        /**
         * Returns the Main instance for this batch.
         **/
        Main enclosingMain() {
            return Main.this;
        }
    }
}

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