httpurlconnection.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/util/HttpURLConnection.java,v 1.15 2004/04/18 23:51:38 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.util;

import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.Header;

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.ProtocolException;
import java.security.Permission;

/**
 * Provides a <code>HttpURLConnection</code> wrapper around HttpClient's
 * <code>HttpMethod</code>. This allows existing code to easily switch to
 * HttpClieht without breaking existing interfaces using the JDK
 * <code>HttpURLConnection</code>.
 *
 * Note 1: The current implementations wraps only a connected
 * <code>HttpMethod</code>, ie a method that has alreayd been used to connect
 * to an HTTP server.
 *
 * Note 2: It is a best try effort as different version of the JDK have
 * different behaviours for <code>HttpURLConnection</code> (And I'm not even
 * including the numerous <code>HttpURLConnection</code> bugs!).
 *
 * @author <a href="mailto:[e-mail]">Vincent Massol</a>
 * @author <a href="mailto:[e-mail]">Jeff Dever</a>
 * @author <a href="mailto:[e-mail]">Mike Bowler</a>
 *
 * @since 2.0
 *
 * @version $Id: HttpURLConnection.java 480424 2006-11-29 05:56:49Z bayard $
 */
public class HttpURLConnection extends java.net.HttpURLConnection {

    // -------------------------------------------------------- Class Variables
   
    /** Log object for this class. */
    private static final Log LOG = LogFactory.getLog(HttpURLConnection.class);


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

    /**
     * The <code>HttpMethod</code> object that was used to connect to the
     * HTTP server. It contains all the returned data.
     */
    private HttpMethod method;

    /**
     * The URL to which we are connected
     */
    private URL url;



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

    /**
     * Creates an <code>HttpURLConnection</code> from a <code>HttpMethod</code>.
     *
     * @param method the theMethod that was used to connect to the HTTP
     *        server and which contains the returned data.
     * @param url the URL to which we are connected (includes query string)
     */
    public HttpURLConnection(HttpMethod method, URL url) {
        super(url);
        this.method = method;
        this.url = url;
    }

    /**
     * Create an instance.
     * @param url The URL.
     * @see java.net.HttpURLConnection#HttpURLConnection(URL)
     */
    protected HttpURLConnection(URL url) {
        super(url);
        throw new RuntimeException("An HTTP URL connection can only be "
            + "constructed from a HttpMethod class");
    }


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

    /** 
     * Gets an input stream for the HttpMethod response body.
     * @throws IOException If an IO problem occurs.
     * @return The input stream.
     * @see java.net.HttpURLConnection#getInputStream()
     * @see org.apache.commons.httpclient.HttpMethod#getResponseBodyAsStream()
     */
    public InputStream getInputStream() throws IOException {
        LOG.trace("enter HttpURLConnection.getInputStream()");
        return this.method.getResponseBodyAsStream();
    }

    /**
     * Not yet implemented.
     * Return the error stream.
     * @see java.net.HttpURLConnection#getErrorStream()
     */
    public InputStream getErrorStream() {
        LOG.trace("enter HttpURLConnection.getErrorStream()");
        throw new RuntimeException("Not implemented yet");
    }

    /**
     * Not yet implemented.
     * @see java.net.HttpURLConnection#disconnect()
     */
    public void disconnect() {
        LOG.trace("enter HttpURLConnection.disconnect()");
        throw new RuntimeException("Not implemented yet");
    }

    /**
     * Not available: the data must have already been retrieved.
     * @throws IOException If an IO problem occurs.
     * @see java.net.HttpURLConnection#connect()
     */
    public void connect() throws IOException {
        LOG.trace("enter HttpURLConnection.connect()");
        throw new RuntimeException("This class can only be used with already"
            + "retrieved data");
    }

    /**
     * Not yet implemented.
     * @return true if we are using a proxy.
     * @see java.net.HttpURLConnection#usingProxy()
     */
    public boolean usingProxy() {
        LOG.trace("enter HttpURLConnection.usingProxy()");
        throw new RuntimeException("Not implemented yet");
    }

    /**
     * Return the request method.
     * @return The request method.
     * @see java.net.HttpURLConnection#getRequestMethod()
     * @see org.apache.commons.httpclient.HttpMethod#getName()
     */
    public String getRequestMethod() {
        LOG.trace("enter HttpURLConnection.getRequestMethod()");
        return this.method.getName();
    }

    /**
     * Return the response code.
     * @return The response code.
     * @throws IOException If an IO problem occurs.
     * @see java.net.HttpURLConnection#getResponseCode()
     * @see org.apache.commons.httpclient.HttpMethod#getStatusCode()
     */
    public int getResponseCode() throws IOException {
        LOG.trace("enter HttpURLConnection.getResponseCode()");
        return this.method.getStatusCode();
    }

    /**
     * Return the response message
     * @return The response message
     * @throws IOException If an IO problem occurs.
     * @see java.net.HttpURLConnection#getResponseMessage()
     * @see org.apache.commons.httpclient.HttpMethod#getStatusText()
     */
    public String getResponseMessage() throws IOException {
        LOG.trace("enter HttpURLConnection.getResponseMessage()");
        return this.method.getStatusText();
    }

    /**
     * Return the header field
     * @param name the name of the header
     * @return the header field.
     * @see java.net.HttpURLConnection#getHeaderField(String)
     * @see org.apache.commons.httpclient.HttpMethod#getResponseHeaders()
     */
    public String getHeaderField(String name) {
        LOG.trace("enter HttpURLConnection.getHeaderField(String)");
        // Note: Return the last matching header in the Header[] array, as in
        // the JDK implementation.
        Header[] headers = this.method.getResponseHeaders();
        for (int i = headers.length - 1; i >= 0; i--) {
            if (headers[i].getName().equalsIgnoreCase(name)) {
                return headers[i].getValue();
            }
        }

        return null;
    }

    /**
     * Return the header field key
     * @param keyPosition The key position
     * @return The header field key.
     * @see java.net.HttpURLConnection#getHeaderFieldKey(int)
     * @see org.apache.commons.httpclient.HttpMethod#getResponseHeaders()
     */
    public String getHeaderFieldKey(int keyPosition) {
        LOG.trace("enter HttpURLConnection.getHeaderFieldKey(int)");

        // Note: HttpClient does not consider the returned Status Line as
        // a response header. However, getHeaderFieldKey(0) is supposed to 
        // return null. Hence the special case below ...
        
        if (keyPosition == 0) {
            return null;
        }

        // Note: HttpClient does not currently keep headers in the same order
        // that they are read from the HTTP server.

        Header[] headers = this.method.getResponseHeaders();
        if (keyPosition < 0 || keyPosition > headers.length) {
            return null;
        }

        return headers[keyPosition - 1].getName();