Java example source code file (Reader.java)

This example Java source code file (Reader.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

bufferedinputstream, fileinputstream, hprofreader, ioexception, positiondatainputstream, reader, snapshot, string, unrecognized

The Reader.java Java example source code

/*
 * Copyright (c) 1997, 2008, 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.
 */


/*
 * The Original Code is HAT. The Initial Developer of the
 * Original Code is Bill Foote, with contributions from others
 * at JavaSoft/Sun.
 */

package com.sun.tools.hat.internal.parser;

import java.io.*;
import com.sun.tools.hat.internal.model.*;

/**
 * Abstract base class for reading object dump files.  A reader need not be
 * thread-safe.
 *
 * @author      Bill Foote
 */


public abstract class Reader {
    protected PositionDataInputStream in;

    protected Reader(PositionDataInputStream in) {
        this.in = in;
    }

    /**
     * Read a snapshot from a data input stream.  It is assumed that the magic
     * number has already been read.
     */
    abstract public Snapshot read() throws IOException;

    /**
     * Read a snapshot from a file.
     *
     * @param heapFile The name of a file containing a heap dump
     * @param callStack If true, read the call stack of allocaation sites
     */
    public static Snapshot readFile(String heapFile, boolean callStack,
                                    int debugLevel)
            throws IOException {
        int dumpNumber = 1;
        int pos = heapFile.lastIndexOf('#');
        if (pos > -1) {
            String num = heapFile.substring(pos+1, heapFile.length());
            try {
                dumpNumber = Integer.parseInt(num, 10);
            } catch (java.lang.NumberFormatException ex) {
                String msg = "In file name \"" + heapFile
                             + "\", a dump number was "
                             + "expected after the :, but \""
                             + num + "\" was found instead.";
                System.err.println(msg);
                throw new IOException(msg);
            }
            heapFile = heapFile.substring(0, pos);
        }
        PositionDataInputStream in = new PositionDataInputStream(
            new BufferedInputStream(new FileInputStream(heapFile)));
        try {
            int i = in.readInt();
            if (i == HprofReader.MAGIC_NUMBER) {
                Reader r
                    = new HprofReader(heapFile, in, dumpNumber,
                                      callStack, debugLevel);
                return r.read();
            } else {
                throw new IOException("Unrecognized magic number: " + i);
            }
        } finally {
            in.close();
        }
    }
}