Glassfish example source code file (InputReader.java)

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

Java - Glassfish tags/keywords

bufferedreader, end, inputexception, inputexception, inputreader, inputreader, io, ioexception, ioexception, reader, stepping, string, string, stringreader, substring

The Glassfish InputReader.java source code

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2009-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package org.glassfish.admin.rest.readers;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;


/**
 * @author rajeshwar patil
 */
public class InputReader {

    /**
     * Construct a InputReader from a string.
     *
     * @param reader     A reader.
     */
    public InputReader(Reader reader) {
        this.reader = reader.markSupported() ? 
        		reader : new BufferedReader(reader);
        this.useLastChar = false;
        this.index = 0;
    }


    /**
     * Construct a InputReader from a string.
     *
     * @param s     A source string.
     */
    public InputReader(String s) {
        this(new StringReader(s));
    }


    /**
     * Back up one character.
     */
    public void back() throws InputException {
        if (useLastChar || index <= 0) {
            throw new InputException("Stepping back two steps is not supported");
        }
        index -= 1;
        useLastChar = true;
    }


    /**
    * Get the next character in the source string.
     *
     * @return The next character, or 0 if past the end of the source string.
     */
    public char next() throws InputException {
        if (this.useLastChar) {
        	this.useLastChar = false;
            if (this.lastChar != 0) {
            	this.index += 1;
            }
            return this.lastChar;
        } 
        int c;
        try {
            c = this.reader.read();
        } catch (IOException exc) {
            throw new InputException(exc);
        }

        if (c <= 0) { // End of stream
        	this.lastChar = 0;
            return 0;
        } 
    	this.index += 1;
    	this.lastChar = (char) c;
        return this.lastChar;
    }


    /**
     * Resturns InputException to signal a syntax error.
     *
     * @param message The error message.
     * @return  A InputException object, suitable for throwing
     */
    public InputException error(String message) {
        return new InputException(message + toString());
    }


    /**
     * Get the next char in the string, skipping whitespace.
     * @throws InputException
     * @return  A character, or 0 if there are no more characters.
     */
    public char nextNonSpace() throws InputException {
        for (;;) {
            char c = next();
            if (c == 0 || c > ' ') {
                return c;
            }
        }
    }


    /**
     * Get the next n characters.
     *
     * @param n     The number of characters to take.
     * @return      A string of n characters.
     * @throws InputException
     *   Substring bounds error if there are not
     *   n characters remaining in the source string.
     */
    public String next(int n) throws InputException {
        if (n == 0) {
            return "";
        }

        char[] buffer = new char[n];
        int pos = 0;

        if (this.useLastChar) {
            this.useLastChar = false;
            buffer[0] = this.lastChar;
            pos = 1;
        } 

        try {
            int len;
            while ((pos < n) && ((len = reader.read(buffer, pos, n - pos)) != -1)) {
                pos += len;
            }
        } catch (IOException exc) {
            throw new InputException(exc);
        }
        this.index += pos;

        if (pos < n) {
            throw error("Substring bounds error");
        }

        this.lastChar = buffer[n - 1];
        return new String(buffer);
    }


    /**
     * Determine if the source string still contains characters that next()
     * can consume.
     * @return true if not yet at the end of the source.
     */
    public boolean more() throws InputException {
        char nextChar = next();
        if (nextChar == 0) {
            return false;
        } 
        back();
        return true;
    }


    private int index;
    private Reader reader;
    private char lastChar;
    private boolean useLastChar;

}