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Java example source code file (ClassDump.java)

This example Java source code file (ClassDump.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

bufferedoutputstream, classdump, classfilter, classwriter, constructor, file, fileoutputstream, ioexception, jar, jarentry, jaroutputstream, manifest, reflection, string, systemdictionary, tool

The ClassDump.java Java example source code

/*
 * Copyright (c) 2002, 2013, 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.
 *
 * 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.jvm.hotspot.tools.jcore;

import java.io.*;
import java.lang.reflect.Constructor;
import java.util.jar.JarOutputStream;
import java.util.jar.JarEntry;
import java.util.jar.Manifest;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.debugger.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.tools.*;

public class ClassDump extends Tool {
    private ClassFilter classFilter;
    private String      outputDirectory;
    private JarOutputStream jarStream;
    private String      pkgList;

    public ClassDump() {
        super();
    }

    public ClassDump(JVMDebugger d, String pkgList) {
        super(d);
        this.pkgList = pkgList;
    }

    public void setClassFilter(ClassFilter cf) {
        classFilter = cf;
    }

    public void setOutputDirectory(String od) {
        outputDirectory = od;
        if (jarStream != null) {
            try {
                jarStream.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
        jarStream = null;
    }

    public void setJarOutput(String jarFileName) throws IOException {
        jarStream = new JarOutputStream(new FileOutputStream(jarFileName), new Manifest());
        outputDirectory = null;
    }

    public void run() {
        // Ready to go with the database...
        try {
            if (classFilter == null) {
                // If not already set, the name of the filter comes from a System property.
                // If we have a pkgList, pass it, otherwise let the filter read
                // its own System property for the list of classes.
                String filterClassName = System.getProperty("sun.jvm.hotspot.tools.jcore.filter",
                                                            "sun.jvm.hotspot.tools.jcore.PackageNameFilter");
                try {
                    Class filterClass = Class.forName(filterClassName);
                    if (pkgList == null) {
                        classFilter = (ClassFilter) filterClass.newInstance();
                    } else {
                        Constructor con = filterClass.getConstructor(String.class);
                        classFilter = (ClassFilter) con.newInstance(pkgList);
                    }
                } catch(Exception exp) {
                    System.err.println("Warning: Can not create class filter!");
                }
            }

            // outputDirectory and jarStream are alternatives: setting one closes the other.
            // If neither is set, use outputDirectory from the System property:
            if (outputDirectory == null && jarStream == null) {
                String dirName = System.getProperty("sun.jvm.hotspot.tools.jcore.outputDir", ".");
                setOutputDirectory(dirName);
            }

            // walk through the system dictionary
            SystemDictionary dict = VM.getVM().getSystemDictionary();
            dict.classesDo(new SystemDictionary.ClassVisitor() {
                    public void visit(Klass k) {
                        if (k instanceof InstanceKlass) {
                            try {
                                dumpKlass((InstanceKlass) k);
                            } catch (Exception e) {
                                System.out.println(k.getName().asString());
                                e.printStackTrace();
                            }
                        }
                    }
                });
        }
        catch (AddressException e) {
            System.err.println("Error accessing address 0x"
                               + Long.toHexString(e.getAddress()));
            e.printStackTrace();
        }
        if (jarStream != null) {
            try {
                jarStream.close();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
            jarStream = null;
        }
    }

    public String getName() {
        return "jcore";
    }

    private void dumpKlass(InstanceKlass kls) {
        if (classFilter != null && ! classFilter.canInclude(kls) ) {
            return;
        }

        String klassName = kls.getName().asString();
        klassName = klassName.replace('/', File.separatorChar);
        try {
            OutputStream os = null;
            if (jarStream != null) {
                jarStream.putNextEntry(new JarEntry(klassName + ".class"));
                os = jarStream;
            } else {
                int index = klassName.lastIndexOf(File.separatorChar);
                File dir = null;
                if (index != -1) {
                    String dirName = klassName.substring(0, index);
                    dir = new File(outputDirectory,  dirName);
                } else {
                    dir = new File(outputDirectory);
                }

                dir.mkdirs();
                File f = new File(dir, klassName.substring(index + 1) + ".class");
                f.createNewFile();
                os = new BufferedOutputStream(new FileOutputStream(f));
            }
            try {
                ClassWriter cw = new ClassWriter(kls, os);
                cw.write();
            } finally {
                if (os != jarStream) {
                    os.close();
                }
            }
        } catch(IOException exp) {
            exp.printStackTrace();
        }
    }

    public static void main(String[] args) {

        ClassDump cd = new ClassDump();
        cd.execute(args);
    }
}

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