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Apache HttpComponents Core (blocking I/O) for jdk 1.5
There is a newer version: 4.4.3
/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * .
 *
 */

package org.apache.http.message;

import org.apache.http.Header;
import org.apache.http.HttpVersion;
import org.apache.http.ParseException;
import org.apache.http.ProtocolVersion;
import org.apache.http.RequestLine;
import org.apache.http.StatusLine;
import org.apache.http.annotation.Immutable;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.Args;
import org.apache.http.util.CharArrayBuffer;

/**
 * Basic parser for lines in the head section of an HTTP message.
 * There are individual methods for parsing a request line, a
 * status line, or a header line.
 * The lines to parse are passed in memory, the parser does not depend
 * on any specific IO mechanism.
 * Instances of this class are stateless and thread-safe.
 * Derived classes MUST maintain these properties.
 *
 * 
 * Note: This class was created by refactoring parsing code located in
 * various other classes. The author tags from those other classes have
 * been replicated here, although the association with the parsing code
 * taken from there has not been traced.
 * 
 *
 * @since 4.0
 */
@Immutable
public class BasicLineParser implements LineParser {

    /**
     * A default instance of this class, for use as default or fallback.
     * Note that {@link BasicLineParser} is not a singleton, there can
     * be many instances of the class itself and of derived classes.
     * The instance here provides non-customized, default behavior.
     *
     * @deprecated (4.3) use {@link #INSTANCE}
     */
    @Deprecated
    public final static BasicLineParser DEFAULT = new BasicLineParser();

    public final static BasicLineParser INSTANCE = new BasicLineParser();

    /**
     * A version of the protocol to parse.
     * The version is typically not relevant, but the protocol name.
     */
    protected final ProtocolVersion protocol;


    /**
     * Creates a new line parser for the given HTTP-like protocol.
     *
     * @param proto     a version of the protocol to parse, or
     *                  {@code null} for HTTP. The actual version
     *                  is not relevant, only the protocol name.
     */
    public BasicLineParser(final ProtocolVersion proto) {
        this.protocol = proto != null? proto : HttpVersion.HTTP_1_1;
    }


    /**
     * Creates a new line parser for HTTP.
     */
    public BasicLineParser() {
        this(null);
    }


    public static
        ProtocolVersion parseProtocolVersion(final String value,
                                             final LineParser parser) throws ParseException {
        Args.notNull(value, "Value");

        final CharArrayBuffer buffer = new CharArrayBuffer(value.length());
        buffer.append(value);
        final ParserCursor cursor = new ParserCursor(0, value.length());
        return (parser != null ? parser : BasicLineParser.INSTANCE)
                .parseProtocolVersion(buffer, cursor);
    }


    // non-javadoc, see interface LineParser
    @Override
    public ProtocolVersion parseProtocolVersion(final CharArrayBuffer buffer,
                                                final ParserCursor cursor) throws ParseException {
        Args.notNull(buffer, "Char array buffer");
        Args.notNull(cursor, "Parser cursor");
        final String protoname = this.protocol.getProtocol();
        final int protolength  = protoname.length();

        final int indexFrom = cursor.getPos();
        final int indexTo = cursor.getUpperBound();

        skipWhitespace(buffer, cursor);

        int i = cursor.getPos();

        // long enough for "HTTP/1.1"?
        if (i + protolength + 4 > indexTo) {
            throw new ParseException
                ("Not a valid protocol version: " +
                 buffer.substring(indexFrom, indexTo));
        }

        // check the protocol name and slash
        boolean ok = true;
        for (int j=0; ok && (j buffer.length()) {
            return false;
        }


        // just check protocol name and slash, no need to analyse the version
        boolean ok = true;
        for (int j=0; ok && (j