optionsmethod.java

Light in the box 抓取程序。 使用HttpClient

/*
 * $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/methods/OptionsMethod.java,v 1.15 2004/04/18 23:51:37 jsdever Exp $
 * $Revision: 480424 $
 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
 *
 * ====================================================================
 *
 *  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
 * <http://www.apache.org/>.
 *
 */

package org.apache.commons.httpclient.methods;

import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.HttpConnection;
import org.apache.commons.httpclient.HttpMethodBase;
import org.apache.commons.httpclient.HttpState;

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.util.Vector;


/**
 * Implements the HTTP OPTIONS method.
 * <p>
 * The HTTP OPTIONS method is defined in section 9.2 of 
 * <a href="http://www.ietf.org/rfc/rfc2616.txt">RFC2616</a>:
 * <blockquote>
 *  The OPTIONS method represents a request for information about the
 *  communication options available on the request/response chain
 *  identified by the Request-URI. This method allows the client to
 *  determine the options and/or requirements associated with a resource,
 *  or the capabilities of a server, without implying a resource action
 *  or initiating a resource retrieval.
 * </blockquote>
 * </p>
 *
 * @author <a href="mailto:[e-mail]">Remy Maucherat</a>
 * @author <a href="mailto:[e-mail]">Mike Bowler</a>
 * @author <a href="mailto:[e-mail]">Jeff Dever</a>
 *
 * @version $Revision: 480424 $
 * @since 1.0
 */
public class OptionsMethod
    extends HttpMethodBase {


    // --------------------------------------------------------- Class Variables

    /** Log object for this class. */
    private static final Log LOG = LogFactory.getLog(OptionsMethod.class);

    // ----------------------------------------------------------- Constructors


    /**
     * Method constructor.
     *
     * @since 1.0
     */
    public OptionsMethod() {
    }


    /**
     * Constructor specifying a URI.
     *
     * @param uri either an absolute or relative URI
     *
     * @since 1.0
     */
    public OptionsMethod(String uri) {
        super(uri);
    }


    // ----------------------------------------------------- Instance Variables


    /**
     * Methods allowed.
     */
    private Vector methodsAllowed = new Vector();


    // --------------------------------------------------------- Public Methods

    /**
     * Get the name.
     * @return "OPTIONS"
     * @since 2.0
     */
    public String getName() {
        return "OPTIONS";
    }


    /**
     * Is the specified method allowed ?
     * 
     * @param method The method to check.
     * @return true if the specified method is allowed.
     * @since 1.0
     */
    public boolean isAllowed(String method) {
        checkUsed();
        return methodsAllowed.contains(method);
    }


    /**
     * Get a list of allowed methods.
     * @return An enumeration of all the allowed methods.
     *
     * @since 1.0
     */
    public Enumeration getAllowedMethods() {
        checkUsed();
        return methodsAllowed.elements();
    }


    // ----------------------------------------------------- HttpMethod Methods

    /**
     * <p>
     * This implementation will parse the <tt>Allow</tt> header to obtain 
     * the set of methods supported by the resource identified by the Request-URI.
     * </p>
     *
     * @param state the {@link HttpState state} information associated with this method
     * @param conn the {@link HttpConnection connection} used to execute
     *        this HTTP method
     *
     * @see #readResponse
     * @see #readResponseHeaders
     * @since 2.0
     */
    protected void processResponseHeaders(HttpState state, HttpConnection conn) {
        LOG.trace("enter OptionsMethod.processResponseHeaders(HttpState, HttpConnection)");

        Header allowHeader = getResponseHeader("allow");
        if (allowHeader != null) {
            String allowHeaderValue = allowHeader.getValue();
            StringTokenizer tokenizer =
                new StringTokenizer(allowHeaderValue, ",");
            while (tokenizer.hasMoreElements()) {
                String methodAllowed =
                    tokenizer.nextToken().trim().toUpperCase();
                methodsAllowed.addElement(methodAllowed);
            }
        }
    }

    /**
     * Return true if the method needs a content-length header in the request.
     *
     * @return true if a content-length header will be expected by the server
     *
     * @since 1.0
     * 
     * @deprecated only entity enclosing methods set content length header
     */
    public boolean needContentLength() {
        return false;
    }


}