PrintService (Java Platform SE 8 )
Keywords: javax.print.PrintService interface
Date: 2015-11-19

javax.print

## Interface PrintService

- All Known Subinterfaces:
    MultiDocPrintService
  All Known Implementing Classes:
    StreamPrintService

      public interface PrintService

  Interface PrintService is the factory for a DocPrintJob. A PrintService describes the capabilities of a Printer and can be queried regarding a printer's supported attributes.

  Example:

         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) {
              }
         }

- - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addPrintServiceAttributeListener(PrintServiceAttributeListener listener)` Registers a listener for events on this PrintService.
    `DocPrintJob` | `createPrintJob()` Creates and returns a PrintJob capable of handling data from any of the supported document flavors.
    `boolean` | `equals(Object obj)` Determines if two services are referring to the same underlying service.
    `<T extends PrintServiceAttribute> T` | `getAttribute(Class<T> category)` Gets the value of the single specified service attribute.
    `PrintServiceAttributeSet` | `getAttributes()` Obtains this print service's set of printer description attributes giving this Print Service's status.
    `Object` | `getDefaultAttributeValue(Class<? extends Attribute> category)` Determines this print service's default printing attribute value in the given category.
    `String` | `getName()` Returns a String name for this print service which may be used by applications to request a particular print service.
    `ServiceUIFactory` | `getServiceUIFactory()` Returns a factory for UI components which allow users to interact with the service in various roles.
    `Class<?>[]` | `getSupportedAttributeCategories()` Determines the printing attribute categories a client can specify when setting up a job for this print service.
    `Object` | `getSupportedAttributeValues(Class<? extends Attribute> category, DocFlavor flavor, AttributeSet attributes)` Determines the printing attribute values a client can specify in the given category when setting up a job for this print service.
    `DocFlavor[]` | `getSupportedDocFlavors()` Determines the print data formats a client can specify when setting up a job for this `PrintService`.
    `AttributeSet` | `getUnsupportedAttributes(DocFlavor flavor, AttributeSet attributes)` Identifies the attributes that are unsupported for a print request in the context of a particular DocFlavor.
    `int` | `hashCode()` This method should be implemented consistently with `equals(Object)`.
    `boolean` | `isAttributeCategorySupported(Class<? extends Attribute> category)` Determines whether a client can specify the given printing attribute category when setting up a job for this print service.
    `boolean` | `isAttributeValueSupported(Attribute attrval, DocFlavor flavor, AttributeSet attributes)` Determines whether a client can specify the given printing attribute value when setting up a job for this Print Service.
    `boolean` | `isDocFlavorSupported(DocFlavor flavor)` Determines if this print service supports a specific `DocFlavor`.
    `void` | `removePrintServiceAttributeListener(PrintServiceAttributeListener listener)` Removes the print-service listener from this print service.

- - ### Method Detail

    - #### getName

          String getName()

      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 `PrinterName` attribute.
      Returns:
        name of the service.

    - #### createPrintJob

          DocPrintJob createPrintJob()

      Creates and returns a PrintJob capable of handling data from any of the supported document flavors.
      Returns:
        a DocPrintJob object

    - #### addPrintServiceAttributeListener

          void addPrintServiceAttributeListener(PrintServiceAttributeListener listener)

      Registers a listener for events on this PrintService.
      Parameters:
        `listener` - a PrintServiceAttributeListener, which monitors the status of a print service
      See Also:
        `removePrintServiceAttributeListener(javax.print.event.PrintServiceAttributeListener)`

    - #### removePrintServiceAttributeListener

          void removePrintServiceAttributeListener(PrintServiceAttributeListener listener)

      Removes the print-service listener from this print service. This means the listener is no longer interested in `PrintService` events.
      Parameters:
        `listener` - a PrintServiceAttributeListener object
      See Also:
        `addPrintServiceAttributeListener(javax.print.event.PrintServiceAttributeListener)`

    - #### getAttributes

          PrintServiceAttributeSet getAttributes()

      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 `getAttributes()` method call: that is, the returned attribute set's contents will not be updated if this print service's attribute set's contents change in the future. To detect changes in attribute values, call `getAttributes()` again and compare the new attribute set to the previous attribute set; alternatively, register a listener for print service events.
      Returns:
        Unmodifiable snapshot of this Print Service's attribute set. May be empty, but not null.

    - #### getAttribute

          <T extends PrintServiceAttribute> T getAttribute(Class<T> category)

      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.
      Parameters:
        `category` - the category of a PrintServiceAttribute supported by this service - may not be null.
      Returns:
        the value of the supported attribute or null if the attribute is not supported by this service.
      Throws:
        `NullPointerException` - if the category is null.
        `IllegalArgumentException` - (unchecked exception) if `category` is not a `Class` that implements interface `PrintServiceAttribute`.

    - #### getSupportedDocFlavors

          DocFlavor[] getSupportedDocFlavors()

      Determines the print data formats a client can specify when setting up a job for this `PrintService`. A print data format is designated by a "doc flavor" (class `DocFlavor`) consisting of a MIME type plus a print data representation class.

      Note that some doc flavors may not be supported in combination with all attributes. Use `getUnsupportedAttributes(..)` to validate specific combinations.

      Returns:
        Array of supported doc flavors, should have at least one element.

    - #### isDocFlavorSupported

          boolean isDocFlavorSupported(DocFlavor flavor)

      Determines if this print service supports a specific `DocFlavor`. This is a convenience method to determine if the `DocFlavor` would be a member of the result of `getSupportedDocFlavors()`.

      Note that some doc flavors may not be supported in combination with all attributes. Use `getUnsupportedAttributes(..)` to validate specific combinations.

      Parameters:
        `flavor` - the `DocFlavor`to query for support.
      Returns:
        `true` if this print service supports the specified `DocFlavor`; `false` otherwise.
      Throws:
        `NullPointerException` - (unchecked exception) Thrown if `flavor` is null.

    - #### getSupportedAttributeCategories

          Class<?>[] getSupportedAttributeCategories()

      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 `Class` that implements interface `Attribute`. This method returns just the attribute categories that are supported; it does not return the particular attribute values that are supported.

      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 `DocFlavor`). Use one of the methods that include a `DocFlavor` to validate the request before submitting it, such as `getSupportedAttributeValues(..)`.

      Returns:
        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 `Class` that implements interface `Attribute`. The array is empty if no categories are supported.

    - #### isAttributeCategorySupported

          boolean isAttributeCategorySupported(Class<? extends Attribute> category)

      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 `Class` that implements interface `Attribute`. This method tells whether the attribute category is supported; it does not tell whether a particular attribute value is supported.

      Some categories may not be supported in a particular context (ie for a particular `DocFlavor`). Use one of the methods which include a `DocFlavor` to validate the request before submitting it, such as `getSupportedAttributeValues(..)`.

      This is a convenience method to determine if the category would be a member of the result of `getSupportedAttributeCategories()`.

      Parameters:
        `category` - Printing attribute category to test. It must be a `Class` that implements interface `Attribute`.
      Returns:
        `true` if this print service supports specifying a doc-level or job-level attribute in `category` in a Print Request; `false` if it doesn't.
      Throws:
        `NullPointerException` - (unchecked exception) Thrown if `category` is null.
        `IllegalArgumentException` - (unchecked exception) Thrown if `category` is not a `Class` that implements interface `Attribute`.

    - #### getDefaultAttributeValue

          Object getDefaultAttributeValue(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 `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.

      Some attributes may not be supported in a particular context (ie for a particular `DocFlavor`). Use one of the methods that include a `DocFlavor` to validate the request before submitting it, such as `getSupportedAttributeValues(..)`.

      Not all attributes have a default value. For example the service will not have a defaultvalue for `RequestingUser` i.e. a null return for a supported category means there is no service default value for that category. Use the `isAttributeCategorySupported(Class)` method to distinguish these cases.

      Parameters:
        `category` - Printing attribute category for which the default attribute value is requested. It must be a `Class` that implements interface `Attribute`.
      Returns:
        Default attribute value for `category`, or null if this Print Service does not support specifying a doc-level or job-level attribute in `category` in a Print Request, or the service does not have a default value for this attribute.
      Throws:
        `NullPointerException` - (unchecked exception) Thrown if `category` is null.
        `IllegalArgumentException` - (unchecked exception) Thrown if `category` is not a `Class` that implements interface `Attribute`.

    - #### getSupportedAttributeValues

          Object getSupportedAttributeValues(Class<? extends Attribute> category,
                                             DocFlavor flavor,
                                             AttributeSet attributes)

      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 `Attribute`.

      If `flavor` is null and `attributes` is null or is an empty set, this method returns all the printing attribute values this Print Service supports for any possible job. If `flavor` is not null or `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 null return value may indicate that specifying this attribute is incompatible with the specified DocFlavor. Also if DocFlavor is not null it must be a flavor supported by this PrintService, else IllegalArgumentException will be thrown.

      If the `attributes` parameter contains an Attribute whose category is the same as the `category` parameter, the service must ignore this attribute in the AttributeSet.

      `DocAttribute`s which are to be specified on the `Doc` must be included in this set to accurately represent the context.

      This method returns an Object because different printing attribute categories indicate the supported attribute values in different ways. The documentation for each printing attribute in package `javax.print.attribute.standard` describes how each attribute indicates its supported values. Possible ways of indicating support include:

      - 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.)
      - 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 `getCategory(Class)`.
      - 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.

      Parameters:
        `category` - Printing attribute category to test. It must be a `Class` that implements interface `Attribute`.
        `flavor` - Doc flavor for a supposed job, or null.
        `attributes` - Set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null.
      Returns:
        Object indicating supported values for `category`, or null if this Print Service does not support specifying a doc-level or job-level attribute in `category` in a Print Request.
      Throws:
        `NullPointerException` - (unchecked exception) Thrown if `category` is null.
        `IllegalArgumentException` - (unchecked exception) Thrown if `category` is not a `Class` that implements interface `Attribute`, or `DocFlavor` is not supported by this service.

    - #### isAttributeValueSupported

          boolean isAttributeValueSupported(Attribute attrval,
                                            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 `Attribute`.

      If `flavor` is null and `attributes` is 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 `flavor` is not null or `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.

      Also if DocFlavor is not null it must be a flavor supported by this PrintService, else IllegalArgumentException will be thrown.

      `DocAttribute`s which are to be specified on the `Doc` must be included in this set to accurately represent the context.

      This is a convenience method to determine if the value would be a member of the result of `getSupportedAttributeValues(...)`.

      Parameters:
        `attrval` - Printing attribute value to test.
        `flavor` - Doc flavor for a supposed job, or null.
        `attributes` - Set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null.
      Returns:
        True if this Print Service supports specifying `attrval` as a doc-level or job-level attribute in a Print Request, false if it doesn't.
      Throws:
        `NullPointerException` - (unchecked exception) if `attrval` is null.
        `IllegalArgumentException` - if flavor is not supported by this PrintService.

    - #### getUnsupportedAttributes

          AttributeSet getUnsupportedAttributes(DocFlavor flavor,
                                                AttributeSet attributes)

      Identifies the attributes that are unsupported for a print request in the context of a particular 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 DocFlavor or an IllegalArgumentException will be thrown. If the return value from this method is null, all attributes are supported.

      `DocAttribute`s which are to be specified on the `Doc` must be included in this set to accurately represent the context.

      If the return value is non-null, all attributes in the returned set are unsupported with this DocFlavor. The returned set does not distinguish attribute categories that are unsupported from unsupported attribute values.

      A supported print request can then be created by removing all unsupported attributes from the original attribute set, except in the case that the DocFlavor is unsupported.

      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.

      Use `isDocFlavorSupported()` to verify that a DocFlavor is supported before calling this method.

      Parameters:
        `flavor` - Doc flavor to test, or null
        `attributes` - Set of printing attributes for a supposed job (both job-level attributes and document-level attributes), or null.
      Returns:
        null if this Print Service supports the print request specification, else the unsupported attributes.
      Throws:
        `IllegalArgumentException` - if`flavor` is not supported by this PrintService.

    - #### getServiceUIFactory

          ServiceUIFactory getServiceUIFactory()

      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 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 `ServiceUIFactory` for more information.
      Returns:
        null or a factory for UI components.

    - #### equals

          boolean equals(Object obj)

      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.

      Clients should call this method to determine if two services are referring to the same underlying service.

      Services must implement this method and return 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.

      Overrides:
        `equals` in class `Object`
      Parameters:
        `obj` - the reference object with which to compare.
      Returns:
        true if this service is the same as the obj argument, false otherwise.
      See Also:
        `Object.hashCode()`, `HashMap`

    - #### hashCode

          int hashCode()

      This method should be implemented consistently with `equals(Object)`.
      Overrides:
        `hashCode` in class `Object`
      Returns:
        hash code of this object.
      See Also:
        `Object.equals(java.lang.Object)`, `System.identityHashCode(java.lang.Object)`

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