urlconnection.java

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// URLConnection.java - Superclass of all communications links between
//			an application and a URL.

/* Copyright (C) 1999, 2000  Free Software Foundation

   This file is part of libgcj.

This software is copyrighted work licensed under the terms of the
Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
details.  */

package java.net;

import java.io.*;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.Hashtable;
import java.util.Map;
import java.util.StringTokenizer;
import java.security.Permission;
import java.security.AllPermission;
import gnu.gcj.io.MimeTypes;

/**
 * @author Warren Levy <[e-mail]>
 * @date March 5, 1999.
 */

/**
 * Written using on-line Java Platform 1.2 API Specification, as well
 * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
 * Status:  One guessContentTypeFrom... methods not implemented.
 *    getContent method assumes content type from response; see comment there.
 */

public abstract class URLConnection
{
  protected URL url;
  protected boolean doInput = true;
  protected boolean doOutput = false;
  protected boolean allowUserInteraction;
  protected boolean useCaches;
  protected long ifModifiedSince = 0L;
  protected boolean connected = false;
  private static boolean defaultAllowUserInteraction = false;
  private static boolean defaultUseCaches = true;
  private static FileNameMap fileNameMap;  // Set by the URLConnection subclass.
  private static ContentHandlerFactory factory;
  private static ContentHandler contentHandler;
  private static Hashtable handlers = new Hashtable();
  private static Locale locale; 
  private static SimpleDateFormat dateFormat1, dateFormat2, dateFormat3;
  private static boolean dateformats_initialized = false;

  /**
   * Creates a URL connection to a given URL. A real connection is not made.
   * Use #connect to do this.
   *
   * @param url The Object to create the URL connection to
   *
   * @see URLConnection:connect
   */
  protected URLConnection(URL url)
  {
    this.url = url;
    allowUserInteraction = defaultAllowUserInteraction;
    useCaches = defaultUseCaches;
  }

  /**
   * Creates a real connection to the object references by the URL given
   * to the constructor
   *
   * @exception IOException If an error occurs
   */
  public abstract void connect() throws IOException;

  /**
   * Returns ths URL to the object.
   */
  public URL getURL()
  {
    return url;
  }

  /**
   * Returns the value of the content-length header field
   */
  public int getContentLength()
  {
    return getHeaderFieldInt("content-length", -1);
  }

  /**
   * Returns the value of the content-type header field
   */
  public String getContentType()
  {
    return getHeaderField("content-type");
  }

  /**
   * Returns the value of the content-encoding header field
   */
  public String getContentEncoding()
  {
    return getHeaderField("content-encoding");
  }

  /**
   * Returns the value of the expires header field
   */
  public long getExpiration()
  {
    return getHeaderFieldDate("expiration", 0L);
  }

  /**
   * Returns the value of the date header field
   */
  public long getDate()
  {
    return getHeaderFieldDate("date", 0L);
  }

  /**
   * Returns the value of the last-modified header field
   */
  public long getLastModified()
  {
    return getHeaderFieldDate("last-modified", 0L);
  }

  /**
   * Returns the value of the n-th header field
   *
   * @param num The number of the header field
   */
  public String getHeaderField(int num)
  {
    // Subclasses for specific protocols override this.
    return null;
  }

  /**
   * Returns the value of the header filed specified by name
   *
   * @param name The name of the header field
   */
  public String getHeaderField(String name)
  {
    // Subclasses for specific protocols override this.
    return null;
  }

  /**
   * Returns a map of all sent header fields
   * 
   * @since 1.4
   */
  public Map getHeaderFields()
  {
    // Subclasses for specific protocols override this.
    return null;
  }

  /**
   * Returns the value of the header filed name as int.
   *
   * @param name The name of the header field
   * @param val The default value
   *
   * @return Returns the value of the header filed or the default value
   * if the field is missing or malformed
   */
  public int getHeaderFieldInt(String name, int val)
  {
    String str = getHeaderField(name);
    try
      {
	if (str != null)
	  val = Integer.parseInt(str);
      }
    catch (NumberFormatException e)
      {
	; // Do nothing; val is the default.
      }
    return val;
  }

  /**
   * Returns the value of a header field parsed as date. The result is then
   * number of milliseconds since January 1st, 1970 GMT.
   *
   * @param name The name of the header field
   * @param val The dafault date
   *
   * @return Returns the date value of the header filed or the default value
   * if the field is missing or malformed
   */
  public long getHeaderFieldDate(String name, long val)
  {
    if (! dateformats_initialized)
      initializeDateFormats();
    String str = getHeaderField(name);
    if (str != null)
      {
        Date date;
	if ((date = dateFormat1.parse(str, new ParsePosition(0))) != null)
	  val = date.getTime();
	else if ((date = dateFormat2.parse(str, new ParsePosition(0))) != null)
	  val = date.getTime();
	else if ((date = dateFormat3.parse(str, new ParsePosition(0))) != null)
	  val = date.getTime();
      }
    return val;
  }

  /**
   * Returns the key of the n-th header field
   *
   * @param num The number of the header field
   */
  public String getHeaderFieldKey(int num)
  {
    // Subclasses for specific protocols override this.
    return null;
  }

  /**
   * Retrieves the content of this URLConnection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support the
   * content type
   */
  public Object getContent() throws IOException
  {
    // FIXME: Doc indicates that other criteria should be applied as
    // heuristics to determine the true content type, e.g. see 
    // guessContentTypeFromName() and guessContentTypeFromStream methods
    // as well as FileNameMap class & fileNameMap field & get/set methods.
    String cType = getContentType();
    contentHandler = setContentHandler(cType);
    if (contentHandler == null)
      return getInputStream();

    return contentHandler.getContent(this);
  }

  /**
   * Retrieves the content of this URLConnection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support the
   * content type
   */
  public Object getContent(Class[] classes) throws IOException
  {
    // FIXME: implement this
    return getContent ();
  }

  /**
   * Returns a permission object representing the permission necessary to make
   * the connection represented by this object. This method returns null if no
   * permission is required to make the connection.
   *
   * @exception IOException If the computation of the permission requires
   * network or file I/O and an exception occurs while computing it
   */
  public Permission getPermission() throws IOException
  {
    // Subclasses may override this.
    return new java.security.AllPermission();
  }

  /**
   * Returns the input stream of the URL connection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support input
   */
  public InputStream getInputStream() throws IOException
  {
    // Subclasses for specific protocols override this.
    throw new UnknownServiceException("Protocol " + url.getProtocol() +
			" does not support input.");
  }

  /**
   * Returns the output stream of the URL connection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support output
   */
  public OutputStream getOutputStream() throws IOException
  {
    // Subclasses for specific protocols override this.
    throw new UnknownServiceException("Protocol " + url.getProtocol() +
			" does not support output.");
  }

  /**
   * Returns a string representation of the URL connection object
   */
  public String toString()
  {
    return this.getClass().getName() + ":" + url.toString();
  }

  /**
   * Sets tha value of the doInput field.
   *
   * @param doinput The new value of the doInput field
   *
   * @exception IllegalStateException If already connected
   */
  public void setDoInput(boolean doinput)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    doInput = doinput;
  }

  /**
   * Returns the current value of the doInput field
   */
  public boolean getDoInput()
  {
    return doInput;
  }

  /**
   * Sets the value of the doOutput field
   *
   * @param dooutput The new value of the doOutput field
   *
   * @exception IllegalStateException If already connected
   */
  public void setDoOutput(boolean dooutput)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    doOutput = dooutput;
  }

  /**
   * Returns the current value of the doOutput field
   */
  public boolean getDoOutput()
  {
    return doOutput;
  }

  /**
   * Sets a new value to the allowUserInteraction field
   *
   * @param allowed The new value
   *
   * @exception IllegalStateException If already connected
   */
  public void setAllowUserInteraction(boolean allowed)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    allowUserInteraction = allowed;
  }

  /**
   * Returns the current value of the allowUserInteraction field
   */
  public boolean getAllowUserInteraction()
  {
    return allowUserInteraction;
  }

  /**
   * Sets the default value if the allowUserInteraction field
   *
   * @param allowed The new default value
   */
  public static void setDefaultAllowUserInteraction(boolean allowed)