PrintService.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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package javax.print;

import javax.print.attribute.Attribute;
import javax.print.attribute.AttributeSet;
import javax.print.attribute.PrintServiceAttribute;
import javax.print.attribute.PrintServiceAttributeSet;
import javax.print.event.PrintServiceAttributeListener;

/**
 * Interface {@code PrintService} is the factory for a {@code DocPrintJob}. A
 * {@code PrintService} describes the capabilities of a printer and can be
 * queried regarding a printer's supported attributes.
 * <p>
 * Example:
 *   <pre>{@code
 *   DocFlavor flavor = DocFlavor.INPUT_STREAM.POSTSCRIPT;
 *   PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet();
 *   aset.add(MediaSizeName.ISO_A4);
 *   PrintService[] pservices =
 *                 PrintServiceLookup.lookupPrintServices(flavor, aset);
 *   if (pservices.length > 0) {
 *       DocPrintJob pj = pservices[0].createPrintJob();
 *       try {
 *           FileInputStream fis = new FileInputStream("test.ps");
 *           Doc doc = new SimpleDoc(fis, flavor, null);
 *           pj.print(doc, aset);
 *        } catch (FileNotFoundException fe) {
 *        } catch (PrintException e) {
 *        }
 *   }
 *   }</pre>
 */
public interface PrintService {

    /**
     * Returns a string name for this print service which may be used by
     * applications to request a particular print service. In a suitable
     * context, such as a name service, this name must be unique. In some
     * environments this unique name may be the same as the user friendly
     * printer name defined as the
     * {@link javax.print.attribute.standard.PrinterName PrinterName} attribute.
     *
     * @return name of the service
     */
    public String getName();

    /**
     * Creates and returns a {@code PrintJob} capable of handling data from any
     * of the supported document flavors.
     *
     * @return a {@code DocPrintJob} object
     */
    public DocPrintJob createPrintJob();

    /**
     * Registers a listener for events on this {@code PrintService}.
     *
     * @param  listener a PrintServiceAttributeListener, which monitors the
     *         status of a print service
     * @see #removePrintServiceAttributeListener
     */
    public void addPrintServiceAttributeListener(
                                       PrintServiceAttributeListener listener);

    /**
     * Removes the print-service listener from this print service. This means
     * the listener is no longer interested in {@code PrintService} events.
     *
     * @param  listener a {@code PrintServiceAttributeListener} object
     * @see #addPrintServiceAttributeListener
     */
    public void removePrintServiceAttributeListener(
                                       PrintServiceAttributeListener listener);

    /**
     * Obtains this print service's set of printer description attributes giving
     * this Print Service's status. The returned attribute set object is
     * unmodifiable. The returned attribute set object is a "snapshot" of this
     * Print Service's attribute set at the time of the {@code getAttributes()}
     * method call: that is, the returned attribute set's contents will
     * <i>not</i> be updated if this print service's attribute set's contents
     * change in the future. To detect changes in attribute values, call
     * {@code getAttributes()} again and compare the new attribute set to the
     * previous attribute set; alternatively, register a listener for print
     * service events.
     *
     * @return unmodifiable snapshot of this Print Service's attribute set. May
     *         be empty, but not {@code null}.
     */
    public PrintServiceAttributeSet getAttributes();

    /**
     * Gets the value of the single specified service attribute. This may be
     * useful to clients which only need the value of one attribute and want to
     * minimize overhead.
     *
     * @param  <T> the type of the specified service attribute
     * @param  category the category of a {@code PrintServiceAttribute}
     *         supported by this service - may not be {@code null}
     * @return the value of the supported attribute or {@code null} if the
     *         attribute is not supported by this service
     * @throws NullPointerException if the category is {@code null}
     * @throws IllegalArgumentException if {@code category} is not a
     *         {@code Class} that implements interface
     *         {@link PrintServiceAttribute PrintServiceAttribute}
     */
    public <T extends PrintServiceAttribute>
        T getAttribute(Class<T> category);

    /**
     * Determines the print data formats a client can specify when setting up a
     * job for this {@code PrintService}. A print data format is designated by a
     * "doc flavor" (class {@link DocFlavor DocFlavor}) consisting of a MIME
     * type plus a print data representation class.
     * <p>
     * Note that some doc flavors may not be supported in combination with all
     * attributes. Use {@code getUnsupportedAttributes(..)} to validate specific
     * combinations.
     *
     * @return array of supported doc flavors, should have at least one element
     */
    public DocFlavor[] getSupportedDocFlavors();

    /**
     * Determines if this print service supports a specific {@code DocFlavor}.
     * This is a convenience method to determine if the {@code DocFlavor} would
     * be a member of the result of {@code getSupportedDocFlavors()}.
     * <p>
     * Note that some doc flavors may not be supported in combination with all
     * attributes. Use {@code getUnsupportedAttributes(..)} to validate specific
     * combinations.
     *
     * @param  flavor the {@code DocFlavor} to query for support
     * @return {@code true} if this print service supports the specified
     *         {@code DocFlavor}; {@code false} otherwise
     * @throws NullPointerException if {@code flavor} is {@code null}
     */
    public boolean isDocFlavorSupported(DocFlavor flavor);

    /**
     * Determines the printing attribute categories a client can specify when
     * setting up a job for this print service. A printing attribute category is
     * designated by a {@code Class} that implements interface
     * {@link Attribute Attribute}. This method returns just the attribute
     * <i>categories</i> that are supported; it does not return the particular
     * attribute <i>values</i> that are supported.
     * <p>
     * This method returns all the printing attribute categories this print
     * service supports for any possible job. Some categories may not be
     * supported in a particular context (ie for a particular
     * {@code DocFlavor}). Use one of the methods that include a
     * {@code DocFlavor} to validate the request before submitting it, such as
     * {@code getSupportedAttributeValues(..)}.
     *
     * @return array of printing attribute categories that the client can
     *         specify as a doc-level or job-level attribute in a Print Request.
     *         Each element in the array is a {@link Class Class} that
     *         implements interface {@link Attribute Attribute}. The array is
     *         empty if no categories are supported.
     */
    public Class<?>[] getSupportedAttributeCategories();

    /**
     * Determines whether a client can specify the given printing attribute
     * category when setting up a job for this print service. A printing
     * attribute category is designated by a {@code Class} that implements
     * interface {@link Attribute Attribute}. This method
     * tells whether the attribute <i>category</i> is supported; it does not
     * tell whether a particular attribute <i>value</i> is supported.
     * <p>
     * Some categories may not be supported in a particular context (ie for a
     * particular {@code DocFlavor}). Use one of the methods which include a
     * {@code DocFlavor} to validate the request before submitting it, such as
     * {@code getSupportedAttributeValues(..)}.
     * <p>
     * This is a convenience method to determine if the category would be a
     * member of the result of {@code getSupportedAttributeCategories()}.
     *
     * @param  category printing attribute category to test. It must be a
     *         {@code Class} that implements interface
     *         {@link Attribute Attribute}.
     * @return {@code true} if this print service supports specifying a
     *         doc-level or job-level attribute in {@code category} in a Print
     *         Request; {@code false} if it doesn't
     * @throws NullPointerException if {@code category} is {@code null}
     * @throws IllegalArgumentException if {@code category} is not a
     *         {@code Class} that implements interface
     *         {@link Attribute Attribute}
     */
    public boolean
        isAttributeCategorySupported(Class<? extends Attribute> category);

    /**
     * Determines this print service's default printing attribute value in the
     * given category. A printing attribute value is an instance of a class that
     * implements interface {@link Attribute Attribute}. If a client sets up a
     * print job and does not specify any attribute value in the given category,
     * this Print Service will use the default attribute value instead.
     * <p>
     * Some attributes may not be supported in a particular context (ie for a
     * particular {@code DocFlavor}). Use one of the methods that include a
     * {@code DocFlavor} to validate the request before submitting it, such as
     * {@code getSupportedAttributeValues(..)}.
     * <p>
     * Not all attributes have a default value. For example the service will not
     * have a default value for {@code RequestingUser} i.e. a {@code null}
     * return for a supported category means there is no service default value
     * for that category. Use the {@code isAttributeCategorySupported(Class)}
     * method to distinguish these cases.
     *
     * @param  category printing attribute category for which the default
     *         attribute value is requested. It must be a {@link Class Class}
     *         that implements interface {@link Attribute Attribute}.
     * @return default attribute value for {@code category}, or {@code null} if
     *         this Print Service does not support specifying a doc-level or
     *         job-level attribute in {@code category} in a Print Request, or
     *         the service does not have a default value for this attribute
     * @throws NullPointerException if {@code category} is {@code null}
     * @throws IllegalArgumentException if {@code category} is not a
     *         {@link Class Class} that implements interface
     *         {@link Attribute Attribute}
     */
    public Object
        getDefaultAttributeValue(Class<? extends Attribute> category);

    /**
     * Determines the printing attribute values a client can specify in the
     * given category when setting up a job for this print service. A printing
     * attribute value is an instance of a class that implements interface
     * {@link Attribute Attribute}.
     * <p>
     * If {@code flavor} is {@code null} and {@code attributes} is {@code null}
     * or is an empty set, this method returns all the printing attribute values
     * this Print Service supports for any possible job. If {@code flavor} is not
     * {@code null} or {@code attributes} is not an empty set, this method
     * returns just the printing attribute values that are compatible with the
     * given doc flavor and/or set of attributes. That is, a {@code null} return
     * value may indicate that specifying this attribute is incompatible with
     * the specified DocFlavor. Also if {@code DocFlavor} is not {@code null} it
     * must be a flavor supported by this {@code PrintService}, else
     * {@code IllegalArgumentException} will be thrown.
     * <p>
     * If the {@code attributes} parameter contains an {@code Attribute} whose
     * category is the same as the {@code category} parameter, the service must
     * ignore this attribute in the {@code AttributeSet}.
     * <p>
     * {@code DocAttribute}s which are to be specified on the {@code Doc} must
     * be included in this set to accurately represent the context.
     * <p>
     * This method returns an {@code Object} because different printing
     * attribute categories indicate the supported attribute values in different
     * ways. The documentation for each printing attribute in package
     * {@link javax.print.attribute.standard javax.print.attribute.standard}
     * describes how each attribute indicates its supported values. Possible
     * ways of indicating support include:
     * <ul>
     *   <li>Return a single instance of the attribute category to indicate that
     *   any value is legal -- used, for example, by an attribute whose value is
     *   an arbitrary text string. (The value of the returned attribute object
     *   is irrelevant.)
     *   <li>Return an array of one or more instances of the attribute category,
     *   containing the legal values -- used, for example, by an attribute with
     *   a list of enumerated values. The type of the array is an array of the
     *   specified attribute category type as returned by its
     *   {@code getCategory(Class)}.
     *   <li>Return a single object (of some class other than the attribute
     *   category) that indicates bounds on the legal values -- used, for
     *   example, by an integer-valued attribute that must lie within a certain
     *   range.
     * </ul>
     *
     * @param  category printing attribute category to test. It must be a
     *         {@link Class Class} that implements interface
     *         {@link Attribute Attribute}.
     * @param  flavor doc flavor for a supposed job, or {@code null}
     * @param  attributes set of printing attributes for a supposed job (both
     *         job-level attributes and document-level attributes), or
     *         {@code null}
     * @return object indicating supported values for {@code category}, or
     *         {@code null} if this Print Service does not support specifying a
     *         doc-level or job-level attribute in {@code category} in a Print
     *         Request
     * @throws NullPointerException if {@code category} is {@code null}
     * @throws IllegalArgumentException if {@code category} is not a
     *         {@link Class Class} that implements interface
     *         {@link Attribute Attribute}, or {@code DocFlavor} is not
     *         supported by this service
     */
    public Object
        getSupportedAttributeValues(Class<? extends Attribute> category,
                                    DocFlavor flavor,
                                    AttributeSet attributes);

    /**
     * Determines whether a client can specify the given printing attribute
     * value when setting up a job for this Print Service. A printing attribute
     * value is an instance of a class that implements interface
     * {@link Attribute Attribute}.
     * <p>
     * If {@code flavor} is {@code null} and {@code attributes} is {@code null}
     * or is an empty set, this method tells whether this Print Service supports
     * the given printing attribute value for some possible combination of doc
     * flavor and set of attributes. If {@code flavor} is not {@code null} or
     * {@code attributes} is not an empty set, this method tells whether this
     * Print Service supports the given printing attribute value in combination
     * with the given doc flavor and/or set of attributes.
     * <p>
     * Also if {@code DocFlavor} is not {@code null} it must be a flavor
     * supported by this {@code PrintService}, else
     * {@code IllegalArgumentException} will be thrown.
     * <p>
     * {@code DocAttribute}s which are to be specified on the {@code Doc} must
     * be included in this set to accurately represent the context.
     * <p>
     * This is a convenience method to determine if the value would be a member
     * of the result of {@code getSupportedAttributeValues(...)}.
     *
     * @param  attrval printing attribute value to test
     * @param  flavor doc flavor for a supposed job, or {@code null}
     * @param  attributes set of printing attributes for a supposed job (both
     *         job-level attributes and document-level attributes), or
     *         {@code null}
     * @return {@code true} if this Print Service supports specifying
     *         {@code attrval} as a doc-level or job-level attribute in a Print
     *         Request, {@code false} if it doesn't
     * @throws NullPointerException if {@code attrval} is {@code null}
     * @throws IllegalArgumentException if flavor is not supported by this
     *         {@code PrintService}
     */
    public boolean isAttributeValueSupported(Attribute attrval,
                                             DocFlavor flavor,
                                             AttributeSet attributes);

    /**
     * Identifies the attributes that are unsupported for a print request in the
     * context of a particular {@code DocFlavor}. This method is useful for
     * validating a potential print job and identifying the specific attributes
     * which cannot be supported. It is important to supply only a supported
     * {@code DocFlavor} or an {@code IllegalArgumentException} will be thrown.
     * If the return value from this method is {@code null}, all attributes are
     * supported.
     * <p>
     * {@code DocAttribute}s which are to be specified on the {@code Doc} must
     * be included in this set to accurately represent the context.
     * <p>
     * If the return value is {@code non-null}, all attributes in the returned
     * set are unsupported with this {@code DocFlavor}. The returned set does
     * not distinguish attribute categories that are unsupported from
     * unsupported attribute values.
     * <p>
     * A supported print request can then be created by removing all unsupported
     * attributes from the original attribute set, except in the case that the
     * {@code DocFlavor} is unsupported.
     * <p>
     * If any attributes are unsupported only because they are in conflict with
     * other attributes then it is at the discretion of the service to select
     * the attribute(s) to be identified as the cause of the conflict.
     * <p>
     * Use {@code isDocFlavorSupported()} to verify that a {@code DocFlavor} is
     * supported before calling this method.
     *
     * @param  flavor doc flavor to test, or {@code null}
     * @param  attributes set of printing attributes for a supposed job (both
     *         job-level attributes and document-level attributes), or
     *         {@code null}
     * @return {@code null} if this Print Service supports the print request
     *         specification, else the unsupported attributes
     * @throws IllegalArgumentException if {@code flavor} is not supported by
     *         this {@code PrintService}
     */
    public AttributeSet getUnsupportedAttributes(DocFlavor flavor,
                                           AttributeSet attributes);

    /**
     * Returns a factory for UI components which allow users to interact with
     * the service in various roles. Services which do not provide any UI should
     * return {@code null}. Print Services which do provide UI but want to be
     * supported in an environment with no UI support should ensure that the
     * factory is not initialised unless the application calls this method to
     * obtain the factory. See {@code ServiceUIFactory} for more information.
     *
     * @return {@code null} or a factory for UI components
     */
    public ServiceUIFactory getServiceUIFactory();

    /**
     * Determines if two services are referring to the same underlying service.
     * Objects encapsulating a print service may not exhibit equality of
     * reference even though they refer to the same underlying service.
     * <p>
     * Clients should call this method to determine if two services are
     * referring to the same underlying service.
     * <p>
     * Services must implement this method and return {@code true} only if the
     * service objects being compared may be used interchangeably by the client.
     * Services are free to return the same object reference to an underlying
     * service if that, but clients must not depend on equality of reference.
     *
     * @param  obj the reference object with which to compare
     * @return {@code true} if this service is the same as the obj argument,
     *         {@code false} otherwise
     */
    public boolean equals(Object obj);

    /**
     * This method should be implemented consistently with
     * {@code equals(Object)}.
     *
     * @return hash code of this object
     */
    public int hashCode();
}