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See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 /** 27 * Provides classes and interfaces that describe the types of Java™ Print 28 * Service attributes and how they can be collected into attribute sets. 29 * 30 * <h3>What is an Attribute?</h3> 31 * When setting up a print job, a client specifies two things: <b>print data</b> 32 * and <b>processing instructions.</b> The print data is the actual content to 33 * be printed. The processing instructions tell the printer how to print the 34 * print data, such as: what media to use, how many copies to print, and whether 35 * to print on one or both sides of a sheet. The client specifies these 36 * processing instructions with the attribute definitions of the Java Print 37 * Service API. 38 * <p> 39 * The print data and the processing instructions are separate entities. This 40 * means that: 41 * <ul> 42 * <li>You can print the same print data at different times using different 43 * processing instructions. 44 * <br> 45 * For example, you can print a slide presentation on US letter-sized white 46 * paper, double-sided, stapled, 20 copies to make handouts for a talk; and 47 * you could print the same slide presentation on US letter-sized 48 * transparencies, single-sided, one copy to make the actual slides for the 49 * talk. 50 * <li>You can use the same processing instructions at different times to 51 * print different data. For example, you could set your default processing 52 * instructions to: US letter-sized paper, double sided, stapled. Whenever you 53 * print a job, it prints with these settings, unless you explicitly override 54 * them. 55 * </ul> 56 * The processing instruction does not specify how the print job processes the 57 * request; each processing instruction is only a description of the results of 58 * a print job. The print job determines the manner in which it achieves the 59 * results specified by the processing instructions. Representing processing 60 * instructions as descriptive items provides more flexibility for implementing 61 * print jobs. 62 * 63 * <h4>Attribute Categories and Values</h4> 64 * Each printer has a set of capabilities, such as the ability to print on 65 * different paper sizes or the ability to print more than one copy. Each of the 66 * capabilities has a range of values. For example, a printer's orientation 67 * capability might have this range of values: [landscape, portrait]. For each 68 * print request, the capability is set to one of these values. The Java Print 69 * Service API uses the term <b>attribute category</b> to refer to a printer 70 * capability and the term <b>attribute value</b> to refer to the value of the 71 * capability. 72 * <p> 73 * In the Java Print Service API, an attribute category is represented by a Java 74 * class implementing the <a href="Attribute.html">Attribute</a> interface. 75 * Attribute values are instances of such a class or one of its subclasses. For 76 * example, to specify the number of copies, an application constructs an 77 * instance of the <a href="standard/Copies.html">Copies</a> class with the 78 * number of desired copies and uses the {@code Copies} instance as part of the 79 * print request. In this case, the {@code Copies} class represents the 80 * attribute category, and the {@code Copies} instance represents the attribute 81 * value. 82 * 83 * <h4><a id="role"></a>Attribute Roles</h4> 84 * When submitting a print job to a printer, the client provides the attributes 85 * describing the characteristics of the print data, such as the document name, 86 * and how the print data should be printed, such as double-sided, five copies. 87 * If a print job consists of multiple pieces of print data, different pieces 88 * might have different processing instructions, such as 8 x 11 inch media for 89 * the first document, and 11 x 17 inch media for another document. 90 * <p> 91 * Once the printer starts processing the print job, additional information 92 * about the job becomes available, which might include: the job state (such as 93 * <i>completed</i> or <i>queued</i>) and the number of pages printed so far. 94 * These pieces of information are also attributes. Attributes can also describe 95 * the printer itself, such as: the printer name, the printer location, and the 96 * number of jobs queued. 97 * <p> 98 * The Java Print Service API defines these different kinds of attributes with 99 * five subinterfaces of {@code Attribute}: 100 * <ul> 101 * <li><a href="DocAttribute.html">DocAttribute</a> specifies a characteristic 102 * of an individual document and the print job settings to be applied to an 103 * individual document. 104 * <li><a href="PrintRequestAttribute.html">PrintRequestAttribute</a> 105 * specifies a setting applied to a whole print job and to all the documents 106 * in the print job. 107 * <li><a href="PrintJobAttribute.html">PrintJobAttribute</a> reports the 108 * status of a print job. 109 * <li><a href="PrintServiceAttribute.html">PrintServiceAttribute</a> reports 110 * the status of a print service. 111 * <li><a href="SupportedValuesAttribute.html">SupportedValuesAttribute</a> 112 * gives the supported values for another attribute. 113 * </ul> 114 * Each attribute class implements one or more of these tagging subinterfaces to 115 * indicate where the attribute can be used in the API. If an attribute class 116 * implements multiple tagging subinterfaces, the attribute can be used in 117 * multiple contexts. For example, the media attribute can apply to one document 118 * in a print job as a {@code DocAttribute} or to an entire print job as a 119 * {@code PrintRequestAttribute}. Certain low-level attributes are never used on 120 * their own but are always aggregated into higher-level attributes. These 121 * low-level attribute classes only implement interface 122 * <a href="Attribute.html">Attribute</a>, not any of the tagging subinterfaces. 123 * <p> 124 * The Java Print Service API defines a group of standard attribute classes 125 * modeled upon the attributes in the Internet Printing Protocol (IPP) version 126 * 1.1. The standard attribute classes are in the subpackage 127 * {@code javax.print.attribute.standard} to keep the actual attribute classes 128 * conceptually separate from the generic apparatus defined in package 129 * {@code javax.print.attribute}. 130 * 131 * <h3>Attribute Sets</h3> 132 * A client usually needs to provide more than one processing instruction when 133 * submitting a print job. For example, the client might need to specify a media 134 * size of A4 and a landscape orientation. To send more than one processing 135 * instruction, the client collects the attributes into an attribute set, which 136 * the Java Print Service API represents with the 137 * <a href="AttributeSet.html">AttributeSet</a> interface. 138 * <p> 139 * The {@code AttributeSet} interface is similar to the 140 * <a href="../../../java/util/Map.html">Map</a> interface: it provides a map of 141 * key to values, in which each key is unique and can contain no more than one 142 * value. However, the {@code AttributeSet} interface is designed to 143 * specifically support the needs of the Java Print Service API. An 144 * {@code AttributeSet} requires that: 145 * <ol type=1> 146 * <li>Each key in an {@code AttributeSet} corresponds to a category, and the 147 * value of the key can only be one of the attribute values that belong to the 148 * category represented by the key. Thus, unlike a {@code Map}, an 149 * {@code AttributeSet} restricts the possible values of a key: an attribute 150 * category cannot be set to an attribute value that does not belong to that 151 * category. 152 * <li>No two attributes from the same category can exist in the same set. For 153 * example, an attribute collection must not contain both a "one-sided" 154 * attribute and a "two-sided" attribute because these two attributes give the 155 * printer conflicting instructions. 156 * <li>Only attributes implementing the {@code Attribute} interface can be 157 * added to the set. 158 * </ol> 159 * The {@code javax.print.attribute} package includes 160 * <a href="HashAttributeSet.html">HashAttributeSet</a> as a concrete 161 * implementation of the attribute set interface. {@code HashAttributeSet} 162 * provides an attribute set based on a hash map. You can use this 163 * implementation or provide your own implementation of interface 164 * {@code AttributeSet}. 165 * <p> 166 * The Java Print Service API provides four specializations of an attribute set 167 * that are restricted to contain just one of the four kinds of attributes, as 168 * discussed in the <a href="#role">Attribute Roles</a> section: 169 * <ul> 170 * <li><a href="DocAttributeSet.html">DocAttributeSet</a> 171 * <li><a href="PrintRequestAttributeSet.html">PrintRequestAttributeSet</a> 172 * <li><a href="PrintJobAttributeSet.html"> PrintJobAttributeSet</a> 173 * <li><a href="PrintServiceAttributeSet.html">PrintServiceAttributeSet</a> 174 * </ul> 175 * Notice that only four kinds of attribute sets are listed here, but there are 176 * five kinds of attributes. Interface 177 * <a href="SupportedValuesAttribute.html">SupportedValuesAttribute</a> denotes 178 * an attribute that gives the supported values for another attribute. 179 * Supported-values attributes are never aggregated into attribute sets, so 180 * there is no attribute set subinterface defined for them. 181 * <p> 182 * In some contexts, an attribute set is read-only, which means that the client 183 * is only allowed to examine an attribute set's contents but not change them. 184 * In other contexts, the attribute set is read-write, which means that the 185 * client is allowed both to examine and to change an attribute set's contents. 186 * For a read-only attribute set, calling a mutating operation throws an 187 * {@code UnmodifiableSetException}. 188 * <p> 189 * Package {@code javax.print.attribute} includes one concrete implementation of 190 * each of the attribute set subinterfaces: 191 * <ul> 192 * <li><a href="HashDocAttributeSet.html"> HashDocAttributeSet</a> 193 * <li><a href="HashPrintRequestAttributeSet.html"> 194 * HashPrintRequestAttributeSet</a>, 195 * <li><a href="HashPrintJobAttributeSet.html">HashPrintJobAttributeSet</a>, 196 * <li><a href="HashPrintServiceAttributeSet.html"> 197 * HashPrintServiceAttributeSet</a>. 198 * </ul> 199 * All of these classes extend 200 * <a href="HashAttributeSet.html">HashAttributeSet</a> and enforce the 201 * restriction that the attribute set is only allowed to contain the 202 * corresponding kind of attribute. 203 * 204 * <h3>Attribute Class Design</h3> 205 * An attribute value is a small, atomic data item, such as an integer or an 206 * enumerated value. The Java Print Service API does not use primitive data 207 * types, such as int, to represent attribute values for these reasons: 208 * <ul> 209 * <li>Primitive data types are not type-safe. For example, a compiler should 210 * not allow a "copies" attribute value to be used for a "sides" attribute. 211 * <li>Some attributes must be represented as a record of several values. One 212 * example is printer resolution, which requires two numbers, such as 600 and 213 * 300 representing 600 x 300 dpi. 214 * </ul> 215 * For type-safety and to represent all attributes uniformly, the Java Print 216 * Service API defines each attribute category as a class, such as class 217 * {@code Copies}, class <a href="standard/Sides.html">Sides</a>, and class 218 * <a href="standard/PrinterResolution.html">PrinterResolution</a>. Each 219 * attribute class wraps one or more primitive data items containing the 220 * attribute's value. Attribute set operations perform frequent comparisons 221 * between attribute category objects when adding attributes, finding existing 222 * attributes in the same category, and looking up an attribute given its 223 * category. Because an attribute category is represented by a class, fast 224 * attribute-value comparisons can be performed with the {@code Class.equals} 225 * method. 226 * <p> 227 * Even though the Java Print Service API includes a large number of different 228 * attribute categories, there are only a few different types of attribute 229 * values. Most attributes can be represented by a small number of data types, 230 * such as: integer values, integer ranges, text, or an enumeration of integer 231 * values. The type of the attribute value that a category accepts is called the 232 * attribute's abstract syntax. To provide consistency and reduce code 233 * duplication, the Java Print Service API defines abstract syntax classes to 234 * represent each abstract syntax, and these classes are used as the parent of 235 * standard attributes whenever possible. The abstract syntax classes are: 236 * <ul> 237 * <li><a href="EnumSyntax.html">EnumSyntax</a> provides a type-safe 238 * enumeration in which enumerated values are represented as singleton 239 * objects. Each enumeration singleton is an instance of the enumeration class 240 * that wraps a hidden int value. 241 * <li><a href="IntegerSyntax.html">IntegerSyntax</a> is the abstract syntax 242 * for integer-valued attributes. 243 * <li><a href="TextSyntax.html">TextSyntax</a> is the abstract syntax for 244 * text-valued attributes, and includes a locale giving the text string's 245 * natural language. 246 * <li><a href="SetOfIntegerSyntax.html">SetOfIntegerSyntax</a> is the 247 * abstract syntax for attributes representing a range or set of integers 248 * <li><a href="ResolutionSyntax.html">ResolutionSyntax</a> is the abstract 249 * syntax for attributes representing resolution values, such as 600x300 250 * dpi. 251 * <li><a href="Size2DSyntax.html">Size2DSyntax</a> is the abstract syntax for 252 * attributes representing a two-dimensional size, such as a paper size of 253 * 8.5 x 11 inches. 254 * <li><a href="DateTimeSyntax.html">DateTimeSyntax</a> is the abstract syntax 255 * for attributes whose value is a date and time. 256 * <li><a href="URISyntax.html">URISyntax</a> is the abstract syntax for 257 * attributes whose value is a Uniform Resource Indicator. 258 * </ul> 259 * The abstract syntax classes are independent of the attributes that use them. 260 * In fact, applications that have nothing to do with printing can use the 261 * abstract syntax classes. Although most of the standard attribute classes 262 * extend one of the abstract syntax classes, no attribute class is required to 263 * extend one of these classes. The abstract syntax classes merely provide a 264 * convenient implementation that can be shared by many attribute classes. 265 * <p> 266 * Each attribute class implements the {@code Attribute} interface, either 267 * directly or indirectly, to mark it as a printing attribute. An attribute 268 * class that can appear in restricted attribute sets in certain contexts also 269 * implements one or more subinterfaces of {@code Attribute}. Most attribute 270 * classes also extend the appropriate abstract syntax class to get the 271 * implementation. Consider the {@code Sides} attribute class: 272 * <blockquote> 273 * <pre>{@code 274 * public class Sides 275 * extends EnumSyntax 276 * implements DocAttribute, PrintRequestAttribute, PrintJobAttribute 277 * { 278 * public final Object getCategory() 279 * { 280 * return Sides.class; 281 * } 282 * ... 283 * }} 284 * </pre> 285 * </blockquote> 286 * <p> 287 * Since every attribute class implements {@code Attribute}, every attribute 288 * class must provide an implementation for the 289 * {@link javax.print.attribute.Attribute#getCategory() getCategory} method, 290 * which returns the attribute category. In the case of {@code Sides}, the 291 * {@code getCategory} method returns {@code Sides.class}. The 292 * {@code getCategory} method is final to ensure that any vendor-defined 293 * subclasses of a standard attribute class appear in the same category. Every 294 * attribute object is immutable once constructed so that attribute object 295 * references can be passed around freely. To get a different attribute value, 296 * construct a different attribute object. 297 * 298 * <h3>Attribute Vendors</h3> 299 * The Java Print Service API is designed so that vendors can: 300 * <ul> 301 * <li>define new vendor-specific values for any standard attribute defined in 302 * <a href="standard/package-summary.html">javax.print.attribute.standard</a>. 303 * <li>define new attribute categories representing the vendor printer's 304 * proprietary capabilities not already supported by the standard attributes. 305 * </ul> 306 * To define a new value for an attribute, a client can construct instances of 307 * such attributes with arbitrary values at runtime. However, an enumerated 308 * attribute using an abstract syntax class of {@code EnumSyntax} specifies all 309 * the possible attribute values at compile time as singleton instances of the 310 * attribute class. This means that new enumerated values cannot be constructed 311 * at run time. To define new vendor-specific values for a standard enumerated 312 * attribute, the vendor must define a new attribute class specifying the new 313 * singleton instances. To ensure that the new attribute values fall in the same 314 * category as the standard attribute values, the new attribute class must be a 315 * subclass of the standard attribute class. 316 * <p> 317 * To define a new attribute category, a vendor defines a new attribute class. 318 * This attribute class, like the standard attribute classes, implements 319 * {@code Attribute} or one of its subinterfaces and extends an abstract syntax 320 * class. The vendor can either use an existing abstract syntax class or define 321 * a new one. The new vendor-defined attribute can be used wherever an 322 * {@code Attribute} is used, such as in an {@code AttributeSet}. 323 * 324 * <h3>Using Attributes</h3> 325 * A typical printing application uses the {@code PrintRequestAttributeSet} 326 * because print-request attributes are the types of attributes that client 327 * usually specifies. This example demonstrates creating an attribute set of 328 * print-request attributes and locating a printer that can print the document 329 * according to the specified attributes: 330 * <blockquote> 331 * <pre>{@code 332 * FileInputStream psStream; 333 * try { 334 * psstream = new FileInputStream("file.ps"); 335 * } catch (FileNotFoundException ffne) { 336 * } 337 * if (psstream == null) { 338 * return; 339 * } 340 * //Set the document type. See the DocFlavor documentation for 341 * //more information. 342 * DocFlavor psInFormat = DocFlavor.INPUT_STREAM.POSTSCRIPT; 343 * Doc myDoc = new SimpleDoc(pstream, psInFormat, null); 344 * PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet(); 345 * aset.add(new Copies(5)); 346 * aset.add(MediaSize.A4); 347 * aset.add(Sides.DUPLEX); 348 * PrintService[] services = 349 * PrintServiceLookup.lookupPrintServices(psInFormat, aset); 350 * if (services.length > 0) { 351 * DocPrintJob job = services[0].createPrintJob(); 352 * try { 353 * job.print(myDoc, aset); 354 * } catch (PrintException pe) {} 355 * } 356 * }</pre> 357 * </blockquote> 358 * <p> 359 * Please note: In the {@code javax.print} APIs, a {@code null} reference 360 * parameter to methods is incorrect unless explicitly documented on the method 361 * as having a meaningful interpretation. Usage to the contrary is incorrect 362 * coding and may result in a run time exception either immediately or at some 363 * later time. {@code IllegalArgumentException} and {@code NullPointerException} 364 * are examples of typical and acceptable run time exceptions for such cases. 365 * 366 * @since 1.4 367 */ 368 package javax.print.attribute;