CatalogFeatures (Java SE 15 & JDK 15)
Description: declaration: module: java.xml, package: javax.xml.catalog, class: CatalogFeatures
Keywords: javax.xml.catalog.CatalogFeatures class

Module java.xml
Package javax.xml.catalog

# Class CatalogFeatures

java.lang.Object
javax.xml.catalog.CatalogFeatures

    public class CatalogFeatures
    extends Object

The CatalogFeatures holds a collection of features and properties.

Catalog Features
Feature | Description | Property Name | System Property [1] | jaxp.properties [1] | Value [2] | Action
--- | --- | --- | --- | --- | --- | ---
Type | Value
FILES | A semicolon-delimited list of URIs to locate the catalog files. The URIs must be absolute and have a URL protocol handler for the URI scheme. | javax.xml.catalog.files | javax.xml.catalog.files | javax.xml.catalog.files | String | URIs | Reads the first catalog as the current catalog; Loads others if no match is found in the current catalog including delegate catalogs if any.
PREFER | Indicates the preference between the public and system identifiers. The default value is public [3]. | javax.xml.catalog.prefer | N/A | N/A | String | `system` | Searches system entries for a match; Searches public entries when external identifier specifies only a public identifier
`public` | Searches system entries for a match; Searches public entries when there is no matching system entry.
DEFER | Indicates that the alternative catalogs including those specified in delegate entries or nextCatalog are not read until they are needed. The default value is true. | javax.xml.catalog.defer [4] | javax.xml.catalog.defer | javax.xml.catalog.defer | String | `true` | Loads alternative catalogs as needed.
`false` | Loads all catalogs[5].
RESOLVE | Determines the action if there is no matching entry found after all of the specified catalogs are exhausted. The default is strict. | javax.xml.catalog.resolve [4] | javax.xml.catalog.resolve | javax.xml.catalog.resolve | String | `strict` | Throws CatalogException if there is no match.
`continue` | Allows the XML parser to continue as if there is no match.
`ignore` | Tells the XML parser to skip the external references if there no match.

[1] There is no System property for the features that marked as "N/A".

[2] The value shall be exactly as listed in this table, case-sensitive. Any unspecified value will result in `IllegalArgumentException`.

[3] The Catalog specification defined complex rules on the prefer attribute. Although the prefer can be public or system, the specification actually made system the preferred option, that is, no matter the option, a system entry is always used if found. Public entries are only considered if the prefer is public and system entries are not found. It is therefore recommended that the prefer attribute be set as public (which is the default).

[4] Although non-standard attributes in the OASIS Catalog specification, `defer` and `resolve` are recognized by the Java Catalog API the same as the `prefer` as being an attribute in the catalog entry of the main catalog. Note that only the attributes specified for the catalog entry of the main Catalog file will be used.

[5] If the intention is to share an entire catalog store, it may be desirable to set the property `javax.xml.catalog.defer` to false to allow the entire catalog to be pre-loaded.

## Scope and Order

Features and properties can be set through the catalog file, the Catalog API, system properties, and `jaxp.properties`, with a preference in the same order.

Properties that are specified as attributes in the catalog file for the catalog and group entries shall take preference over any of the other settings. For example, if a `prefer` attribute is set in the catalog file as in `<catalog prefer="public">`, any other input for the "prefer" property is not necessary or will be ignored.

Properties set through the Catalog API override those that may have been set by system properties and/or in `jaxp.properties`. In case of multiple interfaces, the latest in a procedure shall take preference. For `CatalogFeatures.Feature.FILES`, this means that the URI(s) specified through the methods of the `CatalogManager` will override any that may have been entered through the `CatalogFeatures.Builder`.

System properties when set shall override those in `jaxp.properties`.

The `jaxp.properties` file is typically in the conf directory of the Java installation. The file is read only once by the JAXP implementation and its values are then cached for future use. If the file does not exist when the first attempt is made to read from it, no further attempts are made to check for its existence. It is not possible to change the value of any properties in `jaxp.properties` after it has been read.

A CatalogFeatures instance can be created through its builder as illustrated in the following sample code:

                    CatalogFeatures f = CatalogFeatures.builder()
                            .with(Feature.FILES, "file:///etc/xml/catalog")
                            .with(Feature.PREFER, "public")
                            .with(Feature.DEFER, "true")
                            .with(Feature.RESOLVE, "ignore")
                            .build();

## JAXP XML Processor Support

The Catalog Features are supported throughout the JAXP processors, including SAX and DOM (`javax.xml.parsers`), and StAX parsers (`javax.xml.stream`), Schema Validation (`javax.xml.validation`), and XML Transformation (`javax.xml.transform`). The features described above can be set through JAXP factories or processors that define a setProperty or setAttribute interface. For example, the following code snippet sets a URI to a catalog file on a SAX parser through the `javax.xml.catalog.files` property:

          SAXParserFactory spf = SAXParserFactory.newInstance();
          spf.setFeature(XMLConstants.USE_CATALOG, true); [1]
          SAXParser parser = spf.newSAXParser();
          parser.setProperty(CatalogFeatures.Feature.FILES.getPropertyName(), "file:///etc/xml/catalog");

[1] Note that this statement is not required since the default value of `USE_CATALOG` is true.

The JAXP Processors' support for Catalog depends on both the `USE_CATALOG` feature and the existence of valid Catalog file(s). A JAXP processor will use the Catalog only when the feature is true and valid Catalog file(s) are specified through the `javax.xml.catalog.files` property. It will make no attempt to use the Catalog if either `USE_CATALOG` is set to false, or there is no Catalog file specified.

The JAXP processors will observe the default settings of the `CatalogFeatures`. The processors, for example, will report an Exception by default when no matching entry is found since the default value of the `javax.xml.catalog.resolve` property is strict.

The JAXP processors give preference to user-specified custom resolvers. If such a resolver is registered, it will be used over the CatalogResolver. If it returns null however, the processors will continue resolving with the CatalogResolver. If it returns an empty source, no attempt will be made by the CatalogResolver.

The Catalog support is available for any process in the JAXP library that supports a resolver. The following table lists all such processes.

## Processes with Catalog Support

Processes with Catalog Support
Process | Catalog Entry Type | Example
--- | --- | ---
DTDs and external entities | public, system |
       The following DTD reference:
       <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

       Can be resolved using the following Catalog entry:
       <public publicId="-//W3C//DTD XHTML 1.0 Strict//EN" uri="catalog/xhtml1-strict.dtd"/>
       or
       <systemSuffix systemIdSuffix="html1-strict.dtd" uri="catalog/xhtml1-strict.dtd"/>
XInclude | uri |
       The following XInclude element:
       <xi:include href="http://openjdk.java.net/xml/disclaimer.xml"/>

       can be resolved using a URI entry:
       <uri name="http://openjdk.java.net/xml/disclaimer.xml" uri="file:///pathto/local/disclaimer.xml"/>
       or
       <uriSuffix uriSuffix="disclaimer.xml" uri="file:///pathto/local/disclaimer.xml"/>
XSD import | uri |
       The following import element:
        <xsd:import namespace="http://openjdk.java.net/xsd/XSDImport_person"
                    schemaLocation="http://openjdk.java.net/xsd/XSDImport_person.xsd"/>

       can be resolved using a URI entry:
       <uri name="http://openjdk.java.net/xsd/XSDImport_person.xsd" uri="file:///pathto/local/XSDImport_person.xsd"/>
       or
       <uriSuffix uriSuffix="XSDImport_person.xsd" uri="file:///pathto/local/XSDImport_person.xsd"/>
       or
       <uriSuffix uriSuffix="http://openjdk.java.net/xsd/XSDImport_person" uri="file:///pathto/local/XSDImport_person.xsd"/>
XSD include | uri |
       The following include element:
       <xsd:include schemaLocation="http://openjdk.java.net/xsd/XSDInclude_person.xsd"/>

       can be resolved using a URI entry:
       <uri name="http://openjdk.java.net/xsd/XSDInclude_person.xsd" uri="file:///pathto/local/XSDInclude_person.xsd"/>
       or
       <uriSuffix uriSuffix="XSDInclude_person.xsd" uri="file:///pathto/local/XSDInclude_person.xsd"/>
XSL import and include | uri |
       The following include element:
       <xsl:include href="http://openjdk.java.net/xsl/include.xsl"/>

       can be resolved using a URI entry:
       <uri name="http://openjdk.java.net/xsl/include.xsl" uri="file:///pathto/local/include.xsl"/>
       or
       <uriSuffix uriSuffix="include.xsl" uri="file:///pathto/local/include.xsl"/>
XSL document function | uri |
       The document in the following element:
       <xsl:variable name="dummy" select="document('http://openjdk.java.net/xsl/list.xml')"/>

       can be resolved using a URI entry:
       <uri name="http://openjdk.java.net/xsl/list.xml" uri="file:///pathto/local/list.xml"/>
       or
       <uriSuffix uriSuffix="list.xml" uri="file:///pathto/local/list.xml"/>

Since:
  9

- ## Nested Class Summary

  Nested Classes
  Modifier and Type | Class | Description
  --- | --- | ---
  `static class` | `CatalogFeatures.Builder` | The Builder class for building the CatalogFeatures object.
  `static class` | `CatalogFeatures.Feature` | A Feature type as defined in the Catalog Features table.

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `static CatalogFeatures.Builder` | `builder()` | Returns an instance of the builder for creating the CatalogFeatures object.
  `static CatalogFeatures` | `defaults()` | Returns a CatalogFeatures instance with default settings.
  `String` | `get​(CatalogFeatures.Feature cf)` | Returns the value of the specified feature.

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Method Details

  - ### defaults

    public static CatalogFeatures defaults()
    Returns a CatalogFeatures instance with default settings.
    Returns:
      a default CatalogFeatures instance

  - ### get

    public String get​(CatalogFeatures.Feature cf)
    Returns the value of the specified feature.
    Parameters:
      `cf` - the type of the Catalog feature
    Returns:
      the value of the feature

  - ### builder

    public static CatalogFeatures.Builder builder()
    Returns an instance of the builder for creating the CatalogFeatures object.
    Returns:
      an instance of the builder