001 /*
002 * Copyright 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package javax.print;
027
028 import java.io.InputStream;
029 import java.io.IOException;
030 import java.io.Reader;
031 import java.io.UnsupportedEncodingException;
032
033 import javax.print.attribute.AttributeSet;
034 import javax.print.attribute.DocAttributeSet;
035
036 /**
037 * Interface Doc specifies the interface for an object that supplies one piece
038 * of print data for a Print Job. "Doc" is a short, easy-to-pronounce term
039 * that means "a piece of print data." The client passes to the Print Job an
040 * object that implements interface Doc, and the Print Job calls methods on
041 * that object to obtain the print data. The Doc interface lets a Print Job:
042 * <UL>
043 * <LI>
044 * Determine the format, or "doc flavor" (class {@link DocFlavor DocFlavor}),
045 * in which the print data is available. A doc flavor designates the print
046 * data format (a MIME type) and the representation class of the object
047 * from which the print data comes.
048 * <P>
049 * <LI>
050 * Obtain the print data representation object, which is an instance of the
051 * doc flavor's representation class. The Print Job can then obtain the actual
052 * print data from the representation object.
053 * <P>
054 * <LI>
055 * Obtain the printing attributes that specify additional characteristics of
056 * the doc or that specify processing instructions to be applied to the doc.
057 * Printing attributes are defined in package {@link javax.print.attribute
058 * javax.print.attribute}. The doc returns its printing attributes stored in
059 * an {@link javax.print.attribute.DocAttributeSet javax.print.attribute.DocAttributeSet}.
060 * </UL>
061 * <P>
062 * Each method in an implementation of interface Doc is permitted always to
063 * return the same object each time the method is called.
064 * This has implications
065 * for a Print Job or other caller of a doc object whose print data
066 * representation object "consumes" the print data as the caller obtains the
067 * print data, such as a print data representation object which is a stream.
068 * Once the Print Job has called {@link #getPrintData()
069 * <CODE>getPrintData()</CODE>} and obtained the stream, any further calls to
070 * {@link #getPrintData() <CODE>getPrintData()</CODE>} will return the same
071 * stream object upon which reading may already be in progress, <I>not</I> a new
072 * stream object that will re-read the print data from the beginning. Specifying
073 * a doc object to behave this way simplifies the implementation of doc objects,
074 * and is justified on the grounds that a particular doc is intended to convey
075 * print data only to one Print Job, not to several different Print Jobs. (To
076 * convey the same print data to several different Print Jobs, you have to
077 * create several different doc objects on top of the same print data source.)
078 * <P>
079 * Interface Doc affords considerable implementation flexibility. The print data
080 * might already be in existence when the doc object is constructed. In this
081 * case the objects returned by the doc's methods can be supplied to the doc's
082 * constructor, be stored in the doc ahead of time, and simply be returned when
083 * called for. Alternatively, the print data might not exist yet when the doc
084 * object is constructed. In this case the doc object might provide a "lazy"
085 * implementation that generates the print data representation object (and/or
086 * the print data) only when the Print Job calls for it (when the Print Job
087 * calls the {@link #getPrintData() <CODE>getPrintData()</CODE>} method).
088 * <P>
089 * There is no restriction on the number of client threads that may be
090 * simultaneously accessing the same doc. Therefore, all implementations of
091 * interface Doc must be designed to be multiple thread safe.
092 * <p>
093 * However there can only be one consumer of the print data obtained from a
094 * Doc.
095 * <p>
096 * If print data is obtained from the client as a stream, by calling Doc's
097 * <code>getReaderForText()</code> or <code>getStreamForBytes()</code>
098 * methods, or because the print data source is already an InputStream or
099 * Reader, then the print service should always close these streams for the
100 * client on all job completion conditions. With the following caveat.
101 * If the print data is itself a stream, the service will always close it.
102 * If the print data is otherwise something that can be requested as a stream,
103 * the service will only close the stream if it has obtained the stream before
104 * terminating. That is, just because a print service might request data as
105 * a stream does not mean that it will, with the implications that Doc
106 * implementors which rely on the service to close them should create such
107 * streams only in response to a request from the service.
108 * <P>
109 * <HR>
110 */
111 public interface Doc {
112
113 /**
114 * Determines the doc flavor in which this doc object will supply its
115 * piece of print data.
116 *
117 * @return Doc flavor.
118 */
119 public DocFlavor getDocFlavor();
120
121 /**
122 * Obtains the print data representation object that contains this doc
123 * object's piece of print data in the format corresponding to the
124 * supported doc flavor.
125 * The <CODE>getPrintData()</CODE> method returns an instance of
126 * the representation class whose name is given by <CODE>{@link
127 * #getDocFlavor() getDocFlavor()}.{@link
128 * DocFlavor#getRepresentationClassName()
129 * getRepresentationClassName()}</CODE>, and the return value can be cast
130 * from class Object to that representation class.
131 *
132 * @return Print data representation object.
133 *
134 * @exception IOException
135 * Thrown if the representation class is a stream and there was an I/O
136 * error while constructing the stream.
137 */
138 public Object getPrintData() throws IOException;
139
140 /**
141 * Obtains the set of printing attributes for this doc object. If the
142 * returned attribute set includes an instance of a particular attribute
143 * <I>X,</I> the printer must use that attribute value for this doc,
144 * overriding any value of attribute <I>X</I> in the job's attribute set.
145 * If the returned attribute set does not include an instance
146 * of a particular attribute <I>X</I> or if null is returned, the printer
147 * must consult the job's attribute set to obtain the value for
148 * attribute <I>X,</I> and if not found there, the printer must use an
149 * implementation-dependent default value. The returned attribute set is
150 * unmodifiable.
151 *
152 * @return Unmodifiable set of printing attributes for this doc, or null
153 * to obtain all attribute values from the job's attribute
154 * set.
155 */
156 public DocAttributeSet getAttributes();
157
158 /**
159 * Obtains a reader for extracting character print data from this doc.
160 * The Doc implementation is required to support this method if the
161 * DocFlavor has one of the following print data representation classes,
162 * and return null otherwise:
163 * <UL>
164 * <LI> char[]
165 * <LI> java.lang.String
166 * <LI> java.io.Reader
167 * </UL>
168 * The doc's print data representation object is used to construct and
169 * return a Reader for reading the print data as a stream of characters
170 * from the print data representation object.
171 * However, if the print data representation object is itself a Reader,
172 * then the print data representation object is simply returned.
173 * <P>
174 * @return Reader for reading the print data characters from this doc.
175 * If a reader cannot be provided because this doc does not meet
176 * the criteria stated above, null is returned.
177 *
178 * @exception IOException
179 * Thrown if there was an I/O error while creating the reader.
180 */
181 public Reader getReaderForText() throws IOException;
182
183 /**
184 * Obtains an input stream for extracting byte print data from this
185 * doc. The Doc implementation is required to support this method if
186 * the DocFlavor has one of the following print data representation
187 * classes, and return null otherwise:
188 * <UL>
189 * <LI> byte[]
190 * <LI> java.io.InputStream
191 * </UL>
192 * This doc's print data representation object is obtained, then an input
193 * stream for reading the print data from the print data representation
194 * object as a stream of bytes is created and returned. However, if the
195 * print data representation object is itself an input stream, then the
196 * print data representation object is simply returned.
197 * <P>
198 * @return Input stream for reading the print data bytes from this doc. If
199 * an input stream cannot be provided because this doc does not
200 * meet the criteria stated above, null is returned.
201 *
202 * @exception IOException
203 * Thrown if there was an I/O error while creating the input stream.
204 */
205 public InputStream getStreamForBytes() throws IOException;
206
207 }
|