urlconnection.java

来自「《移动Agent技术》一书的所有章节源代码。」· Java 代码 · 共 1,104 行 · 第 1/3 页

    /**
     * Returns the value of the <code>content-encoding</code> header field.
     *
     * @return  the content encoding of the resource that the URL references,
     *          or <code>null</code> if not known.
     * @see     java.net.URLConnection#getHeaderField(java.lang.String)
     * @since   JDK1.0
     */
    public String getContentEncoding() {
	return getHeaderField("content-encoding");
    }

    /**
     * Returns the value of the <code>expires</code> header field.
     *
     * @return  the expiration date of the resource that this URL references,
     *          or 0 if not known. The value is the number of seconds since
     *          January 1, 1970 GMT.
     * @see     java.net.URLConnection#getHeaderField(java.lang.String)
     * @since   JDK1.0
     */
    public long getExpiration() {
	return getHeaderFieldDate("expires", 0);
    }

    /**
     * Returns the value of the <code>date</code> header field.
     *
     * @return  the sending date of the resource that the URL references,
     *          or <code>0</code> if not known. The value returned is the
     *          number of seconds since January 1, 1970 GMT.
     * @see     java.net.URLConnection#getHeaderField(java.lang.String)
     * @since   JDK1.0
     */
    public long getDate() {
	return getHeaderFieldDate("date", 0);
    }

    /**
     * Returns the value of the <code>last-modified</code> header field.
     * The result is the number of seconds since January 1, 1970 GMT.
     *
     * @return  the date the resource referenced by this
     *          <code>URLConnection</code> was last modified, or 0 if not known.
     * @see     java.net.URLConnection#getHeaderField(java.lang.String)
     * @since   JDK1.0
     */
    public long getLastModified() {
	return getHeaderFieldDate("last-modified", 0);
    }

    /**
     * Returns the value of the specified header field. Names of
     * header fields to pass to this method can be obtained from
     * getHeaderFieldKey.
     *
     * @param   name   the name of a header field.
     * @return  the value of the named header field, or <code>null</code>
     *          if there is no such field in the header.
     * @see     java.net.URLConnection#getHeaderFieldKey(int)
     * @since   JDK1.0
     */
    public String getHeaderField(String name) {
	return null;
    }

    /**
     * Returns the value of the named field parsed as a number.
     * <p>
     * This form of <code>getHeaderField</code> exists because some
     * connection types (e.g., <code>http-ng</code>) have pre-parsed
     * headers. Classes for that connection type can override this method
     * and short-circuit the parsing.
     *
     * @param   name      the name of the header field.
     * @param   Default   the default value.
     * @return  the value of the named field, parsed as an integer. The
     *          <code>Default</code> value is returned if the field is
     *          missing or malformed.
     * @since   JDK1.0
     */
    public int getHeaderFieldInt(String name, int Default) {
	try {
	    return Integer.parseInt(getHeaderField(name));
	} catch(Throwable t) {}
	return Default;
    }

    /**
     * Returns the value of the named field parsed as date.
     * The result is the number of seconds since January 1, 1970 GMT
     * represented by the named field.
     * <p>
     * This form of <code>getHeaderField</code> exists because some
     * connection types (e.g., <code>http-ng</code>) have pre-parsed
     * headers. Classes for that connection type can override this method
     * and short-circuit the parsing.
     *
     * @param   name     the name of the header field.
     * @param   Default   a default value.
     * @return  the value of the field, parsed as a date. The value of the
     *          <code>Default</code> argument is returned if the field is
     *          missing or malformed.
     * @since   JDK1.0
     */
    public long getHeaderFieldDate(String name, long Default) {
	try {
	    return Date.parse(getHeaderField(name));
	} catch(Throwable t) {}
	return Default;
    }

    /**
     * Returns the key for the <code>n</code><sup>th</sup> header field.
     *
     * @param   n   an index.
     * @return  the key for the <code>n</code><sup>th</sup> header field,
     *          or <code>null</code> if there are fewer than <code>n</code>
     *          fields.
     * @since   JDK1.0
     */
    public String getHeaderFieldKey(int n) {
	return null;
    }

    /**
     * Returns the value for the <code>n</code><sup>th</sup> header field.
     * It returns <code>null</code> if there are fewer than
     * <code>n</code> fields.
     * <p>
     * This method can be used in conjunction with the
     * <code>getHeaderFieldKey</code> method to iterate through all
     * the headers in the message.
     *
     * @param   n   an index.
     * @return  the value of the <code>n</code><sup>th</sup> header field.
     * @see     java.net.URLConnection#getHeaderFieldKey(int)
     * @since   JDK1.0
     */
    public String getHeaderField(int n) {
	return null;
    }

    /**
     * Retrieves the contents of this URL connection.
     * <p>
     * This method first determines the content type of the object by
     * calling the <code>getContentType</code> method. If this is
     * the first time that the application has seen that specific content
     * type, a content handler for that content type is created:
     * <ol>
     * <li>If the application has set up a content handler factory instance
     *     using the <code>setContentHandlerFactory</code> method, the
     *     <code>createContentHandler</code> method of that instance is called
     *     with the content type as an argument; the result is a content
     *     handler for that content type.
     * <li>If no content handler factory has yet been set up, or if the
     *     factory's <code>createContentHandler</code> method returns
     *     <code>null</code>, then the application loads the class named:
     *     <ul><code>
     *         sun.net.www.content.&lt;<i>contentType</i>&gt;
     *     </code></ul>
     *     where &lt;<i>contentType</i>&gt; is formed by taking the
     *     content-type string, replacing all slash characters with a
     *     <code>period</code> ('.'), and all other non-alphanumeric characters
     *     with the underscore character '<code>_</code>'. The alphanumeric
     *     characters are specifically the 26 uppercase ASCII letters
     *     '<code>A</code>' through '<code>Z</code>', the 26 lowercase ASCII
     *     letters '<code>a</code>' through '<code>z</code>', and the 10 ASCII
     *     digits '<code>0</code>' through '<code>9</code>'. If the specified
     *     class does not exist, or is not a subclass of
     *     <code>ContentHandler</code>, then an
     *     <code>UnknownServiceException</code> is thrown.
     * </ol>
     *
     * @return     the object fetched. The <code>instanceOf</code> operation
     *               should be used to determine the specific kind of object
     *               returned.
     * @exception  IOException              if an I/O error occurs while
     *               getting the content.
     * @exception  UnknownServiceException  if the protocol does not support
     *               the content type.
     * @see        java.net.ContentHandlerFactory#createContentHandler(java.lang.String)
     * @see        java.net.URLConnection#getContentType()
     * @see        java.net.URLConnection#setContentHandlerFactory(java.net.ContentHandlerFactory)
     * @since      JDK1.0
     */
    public Object getContent() throws IOException {
	return getContentHandler().getContent(this);
    }

    /**
     * Returns an input stream that reads from this open connection.
     *
     * @return     an input stream that reads from this open connection.
     * @exception  IOException              if an I/O error occurs while
     *               creating the input stream.
     * @exception  UnknownServiceException  if the protocol does not support
     *               input.
     * @since   JDK1.0
     */
    public InputStream getInputStream() throws IOException {
	throw new UnknownServiceException("protocol doesn't support input");
    }

    /**
     * Returns an output stream that writes to this connection.
     *
     * @return     an output stream that writes to this connection.
     * @exception  IOException              if an I/O error occurs while
     *               creating the output stream.
     * @exception  UnknownServiceException  if the protocol does not support
     *               output.
     * @since   JDK1.0
     */
    public OutputStream getOutputStream() throws IOException {
	throw new UnknownServiceException("protocol doesn't support output");
    }

    /**
     * Returns a <code>String</code> representation of this URL connection.
     *
     * @return  a string representation of this <code>URLConnection</code>.
     * @since   JDK1.0
     */
    public String toString() {
	return this.getClass().getName() + ":" + url;
    }

    /**
     * Sets the value of the <code>doInput</code> field for this
     * <code>URLConnection</code> to the specified value.
     * <p>
     * A URL connection can be used for input and/or output.  Set the DoInput
     * flag to true if you intend to use the URL connection for input,
     * false if not.  The default is true unless DoOutput is explicitly
     * set to true, in which case DoInput defaults to false.
     *
     * @param   value   the new value.
     * @see     java.net.URLConnection#doInput
     * @since   JDK1.0
     */
    public void setDoInput(boolean doinput) {
	if (connected)
	    throw new IllegalAccessError("Already connected");
	doInput = doinput;
    }

    /**
     * Returns the value of this <code>URLConnection</code>'s
     * <code>doInput</code> flag.
     *
     * @return  the value of this <code>URLConnection</code>'s
     *          <code>doInput</code> flag.
     * @see     java.net.URLConnection#doInput
     * @since   JDK1.0
     */
    public boolean getDoInput() {
	return doInput;
    }

    /**
     * Sets the value of the <code>doOutput</code> field for this
     * <code>URLConnection</code> to the specified value.
     * <p>
     * A URL connection can be used for input and/or output.  Set the DoOutput
     * flag to true if you intend to use the URL connection for output,
     * false if not.  The default is false.
     *
     * @param   value   the new value.
     * @see     java.net.URLConnection#doOutput
     * @since   JDK1.0
     */
    public void setDoOutput(boolean dooutput) {
	if (connected)
	    throw new IllegalAccessError("Already connected");
	doOutput = dooutput;
    }

    /**
     * Returns the value of this <code>URLConnection</code>'s
     * <code>doOutput</code> flag.
     *
     * @return  the value of this <code>URLConnection</code>'s
     *          <code>doOutput</code> flag.
     * @see     java.net.URLConnection#doOutput
     * @since   JDK1.0
     */
    public boolean getDoOutput() {
	return doOutput;
    }

    /**
     * Set the value of the <code>allowUserInteraction</code> field of
     * this <code>URLConnection</code>.
     *
     * @param   allowuserinteraction   the new value.
     * @see     java.net.URLConnection#allowUserInteraction
     * @since   JDK1.0
     */
    public void setAllowUserInteraction(boolean allowuserinteraction) {
	if (connected)
	    throw new IllegalAccessError("Already connected");
	allowUserInteraction = allowuserinteraction;
    }

    /**
     * Returns the value of the <code>allowUserInteraction</code> field for
     * this object.
     *
     * @return  the value of the <code>allowUserInteraction</code> field for
     *          this object.
     * @see     java.net.URLConnection#allowUserInteraction
     * @since   JDK1.0
     */
    public boolean getAllowUserInteraction() {
	return allowUserInteraction;
    }

    /**
     * Sets the default value of the
     * <code>allowUserInteraction</code> field for all future
     * <code>URLConnection</code> objects to the specified value.
     *
     * @param   defaultallowuserinteraction   the new value.
     * @see     java.net.URLConnection#allowUserInteraction
     * @since   JDK1.0
     */
    public static void setDefaultAllowUserInteraction(boolean defaultallowuserinteraction) {
	defaultAllowUserInteraction = defaultallowuserinteraction;
    }

    /**
     * Returns the default value of the <code>allowUserInteraction</code>
     * field.
     * <p>
     * Ths default is "sticky", being a part of the static state of all
     * URLConnections.  This flag applies to the next, and all following
     * URLConnections that are created.
     *
     * @return  the default value of the <code>allowUserInteraction</code>
     *          field.
     * @see     java.net.URLConnection#allowUserInteraction
     * @since   JDK1.0
     */
    public static boolean getDefaultAllowUserInteraction() {
	return defaultAllowUserInteraction;
    }

    /**
     * Sets the value of the <code>useCaches</code> field of this
     * <code>URLConnection</code> to the specified value.
     * <p>
     * Some protocols do caching of documents.  Occasionally, it is important
     * to be able to "tunnel through" and ignore the caches (e.g., the
     * "reload" button in a browser).  If the UseCaches flag on a connection
     * is true, the connection is allowed to use whatever caches it can.
     *  If false, caches are to be ignored.
     *  The default value comes from DefaultUseCaches, which defaults to
     * true.
     *
     * @see     java.net.URLConnection#useCaches
     * @since   JDK1.0
     */
    public void setUseCaches(boolean usecaches) {
	if (connected)
	    throw new IllegalAccessError("Already connected");
	useCaches = usecaches;