Class MetadataStandard

java.lang.Object
org.apache.sis.metadata.MetadataStandard
All Implemented Interfaces:
Serializable
Direct Known Subclasses:
StandardImplementation

public class MetadataStandard extends Object implements Serializable
Enumeration of some metadata standards. A standard is defined by a set of Java interfaces in a specific package or sub-packages. For example, the ISO 19115 standard is defined by GeoAPI interfaces in the
invalid reference
org.opengis.metadata
package and sub-packages.

This class provides some methods operating on metadata instances through Java reflection. The following rules are assumed:

  • Metadata properties are defined by the collection of following getter methods found in the interface, ignoring implementation methods:
    • get*() methods with arbitrary return type;
    • or is*() methods with boolean return type.
  • All properties are readable.
  • A property is also writable if a set*(…) method is defined in the implementation class for the corresponding getter method. The setter method does not need to be defined in the interface.
An instance of MetadataStandard is associated to every AbstractMetadata objects. The AbstractMetadata base class usually form the basis of ISO 19115 implementations but can also be used for other standards.

Defining new MetadataStandard instances

Users should use the predefined constants when applicable. However if new instances need to be defined, then there is a choice:
  • For read-only metadata, MetadataStandard can be instantiated directly. Only getter methods will be used and all operations that modify the metadata properties will throw an UnmodifiableMetadataException.
  • For read/write metadata, the getImplementation(Class) method must be overridden in a MetadataStandard subclass.

Thread safety

The same MetadataStandard instance can be safely used by many threads without synchronization on the part of the caller. Subclasses shall make sure that any overridden methods remain safe to call from multiple threads, because the same MetadataStandard instances are typically referenced by a large amount of ModifiableMetadata.
Since:
0.3
Version:
1.3
See Also:
  • Field Details

    • serialVersionUID

      private static final long serialVersionUID
      For cross-version compatibility.
      See Also:
    • IMPLEMENTATION_CAN_ALTER_API

      static final boolean IMPLEMENTATION_CAN_ALTER_API
      true if implementations can alter the API defined in the interfaces by adding or removing properties. If true, then PropertyAccessor will check for Deprecated and UML annotations in the implementation classes in addition to the interfaces.

      A value of true is useful when Apache SIS implements a newer standard than GeoAPI, but have a slight performance cost at construction time. Performance after construction should be the same.

      See Also:
    • INSTANCES

      static final MetadataStandard[] INSTANCES
      Metadata instances defined in this class. Standards will be tested in the order they appear in this array. So if isSupported(String) may return true for two or more standards, the standard which should have precedence should be declared first.

      The current implementation does not yet contains the user-defined instances. However, it may be something that we will need to do in the future.

    • ISO_19115

      public static final MetadataStandard ISO_19115
      An instance working on ISO 19115 standard as defined by GeoAPI interfaces in the
      invalid reference
      org.opengis.metadata
      package and sub-packages, except quality.
    • ISO_19157

      public static final MetadataStandard ISO_19157
      An instance working on ISO 19157 standard as defined by GeoAPI interfaces in the
      invalid reference
      org.opengis.metadata.quality
      package.
      Since:
      1.3
    • ISO_19111

      public static final MetadataStandard ISO_19111
      An instance working on ISO 19111 standard as defined by GeoAPI interfaces in the
      invalid reference
      org.opengis.referencing
      package and sub-packages.
    • ISO_19123

      public static final MetadataStandard ISO_19123
      An instance working on ISO 19123 standard as defined by GeoAPI interfaces in the org.opengis.coverage package and sub-packages.
    • citation

      final org.opengis.metadata.citation.Citation citation
      Bibliographical reference to the international standard.
      See Also:
    • interfacePackage

      final String interfacePackage
      The root package for metadata interfaces. Must have a trailing '.'.
    • dependencies

      private final MetadataStandard[] dependencies
      The dependencies, or null if none. If non-null, dependencies will be tested in the order they appear in this array. Consequently, if isMetadata(Class) may return true for two or more dependencies, then the dependency which should have precedence should be declared first.

      Note: the null value is for serialization compatibility.

    • accessors

      private final transient ConcurrentMap<CacheKey,Object> accessors
      Accessors for the specified implementation classes. The only legal value types are:
  • Constructor Details

    • MetadataStandard

      public MetadataStandard(org.opengis.metadata.citation.Citation citation, Package interfacePackage, MetadataStandard... dependencies)
      Creates a new instance working on implementation of interfaces defined in the specified package. If this MetadataStandard does not support a given class, then the dependencies will be tested in the order declared to this constructor. Consequently, if isMetadata(Class) may return true for two or more dependencies, then the dependency which should have precedence should be declared first.
      Example:: For the ISO 19157 standard reflected by GeoAPI interfaces, interfacePackage shall be the
      invalid reference
      org.opengis.metadata.quality
      package. Its dependency is ISO_19115 in the
      invalid reference
      org.opengis.metadata
      package.
      Parameters:
      citation - bibliographical reference to the international standard.
      interfacePackage - the root package for metadata interfaces.
      dependencies - the dependencies to other metadata standards.
    • MetadataStandard

      MetadataStandard(String citation, String interfacePackage, MetadataStandard... dependencies)
      Creates a new instance working on implementation of interfaces defined in the specified package. This constructor is used only for the predefined constants.
      Parameters:
      citation - bibliographical reference to the international standard.
      interfacePackage - the root package for metadata interfaces.
      dependencies - the dependencies to other metadata standards, or null if none.
  • Method Details

    • isSupported

      final boolean isSupported(String classname)
      Returns true if class or interface of the given name is supported by this standard. This method verifies if the class is a member of the package given at construction time or a sub-package. This method does not verify if the type is supported by a dependency.
      Parameters:
      classname - the name of the type to verify.
      Returns:
      true if the given type is supported by this standard.
    • forClass

      public static MetadataStandard forClass(Class<?> type)
      Returns the metadata standard for the given class. The argument given to this method can be either an interface defined by the standard, or a class implementing such interface. If the class implements more than one interface, then the first interface recognized by this method, in declaration order, will be retained.

      The current implementation recognizes only the standards defined by the public static constants defined in this class. A future SIS version may recognize user-defined constants.

      Parameters:
      type - the metadata standard interface, or an implementation class.
      Returns:
      the metadata standard for the given type, or null if not found.
    • clearCache

      static void clearCache()
      Clears the cache of accessors. This method is invoked when the classpath changed, in order to discard the references to classes that may need to be unloaded.
    • getCitation

      public org.opengis.metadata.citation.Citation getCitation()
      Returns a bibliographical reference to the international standard. The default implementation return the citation given at construction time.
      Returns:
      bibliographical reference to the international standard.
    • createCacheKey

      private CacheKey createCacheKey(Class<?> type)
      Returns a key for use in getAccessor(CacheKey, boolean) for the given type. The type may be an interface (typically a GeoAPI interface) or an implementation class.
    • getAccessor

      final PropertyAccessor getAccessor(CacheKey key, boolean mandatory)
      Returns the accessor for the specified implementation class, or null if none. The given class shall not be the standard interface, unless the metadata is read-only. More specifically, the given type shall be one of the following:
      Parameters:
      key - the implementation class together with the type declared by the property.
      mandatory - whether this method shall throw an exception or return null if no accessor is found for the given implementation class.
      Returns:
      the accessor for the given implementation, or null if the given class does not implement a metadata interface of the expected package and mandatory is false.
      Throws:
      ClassCastException - if the specified class does not implement a metadata interface of the expected package and mandatory is true.
    • isMetadata

      public boolean isMetadata(Class<?> type)
      Returns true if the given type is assignable to a type from this standard or one of its dependencies. If this method returns true, then invoking getInterface(Class) is guaranteed to succeed without throwing an exception.
      Parameters:
      type - the implementation class (can be null).
      Returns:
      true if the given class is an interface of this standard, or implements an interface of this standard.
    • isMetadata

      private boolean isMetadata(CacheKey key)
      Implementation of isMetadata(Class) with the possibility to specify the property type. We do not provide the additional functionality of this method in public API on the assumption that if the user know the base metadata type implemented by the value, then (s)he already know that the value is a metadata instance.
      See Also:
    • isPendingAPI

      boolean isPendingAPI(Class<?> type)
      Returns true if the given implementation class, normally rejected by findInterface(CacheKey), should be accepted as a pseudo-interface. We use this undocumented feature when Apache SIS experiments a new API which is not yet published in GeoAPI. This happen for example when upgrading Apache SIS public API from the ISO 19115:2003 standard to the ISO 19115:2014 version, but GeoAPI interfaces are still the old version. In such case, API that would normally be present in GeoAPI interfaces are temporarily available only in Apache SIS implementation classes.
    • findInterface

      private Class<?> findInterface(CacheKey key)
      Returns the metadata interface implemented by the specified implementation. Only one metadata interface can be implemented. If the given type is already an interface from the standard, then it is returned directly.

      If the given class is the return value of a property, then the type of that property should be specified in the key.propertyType argument. This information allows this method to take in account only types that are assignable to propertyType, so we can handle classes that implement many metadata interfaces. For example, the org.apache.sis.internal.simple package have various examples of implementing more than one interface for convenience.

      This method ignores dependencies. Fallback on metadata standard dependencies shall be done by the caller.

      Parameters:
      key - the standard interface or the implementation class.
      Returns:
      the single interface, or null if none where found.
    • getInterfaces

      private void getInterfaces(Class<?> type, Class<?> propertyType, Collection<Class<?>> interfaces)
      Puts every interfaces for the given type in the specified collection. This method invokes itself recursively for scanning parent interfaces.

      If the given class is the return value of a property, then the type of that property should be specified in the propertyType argument. This information allows this method to take in account only the types that are assignable to propertyType, so we can handle classes that implement many metadata interfaces. For example, the org.apache.sis.internal.simple package have various examples of implementing more than one interface for convenience.

      See Also:
    • getInterface

      public <T> Class<? super T> getInterface(Class<T> type) throws ClassCastException
      Returns the metadata interface implemented by the specified implementation class. If the given type is already an interface from this standard, then it is returned unchanged.
      Note: The word "interface" may be taken in a looser sense than the usual Java sense because if the given type is defined in this standard package, then it is returned unchanged. The standard package is usually made of interfaces and code lists only, but this is not verified by this method.
      Type Parameters:
      T - the compile-time type.
      Parameters:
      type - the implementation class.
      Returns:
      the interface implemented by the given implementation class.
      Throws:
      ClassCastException - if the specified implementation class does not implement an interface of this standard.
      See Also:
    • getInterface

      final <T> Class<? super T> getInterface(CacheKey key) throws ClassCastException
      Implementation of getInterface(Class) with the possibility to specify the property type. We do not provide the additional functionality of this method in public API on the assumption that users who want to invoke a getInterface(…) method does not know what that interface is. In Apache SIS case, we invoke this method when we almost know what the interface is but want to check if the actual value is a subtype.
      Throws:
      ClassCastException
      See Also:
    • getImplementation

      public <T> Class<? extends T> getImplementation(Class<T> type)
      Returns the implementation class for the given interface, or null if none. If non-null, the returned class must have a public no-argument constructor and the metadata instance created by that constructor must be initially empty (no default value). That no-argument constructor should never throw any checked exception.

      The default implementation returns null in every cases. Subclasses shall override this method in order to map GeoAPI interfaces to their implementation.

      Type Parameters:
      T - the compile-time type.
      Parameters:
      type - the interface, typically from the org.opengis.metadata package.
      Returns:
      the implementation class, or null if none.
    • getTitle

      final Object getTitle(Object metadata)
      Returns a value of the "title" property of the given metadata object. The title property is defined by TitleProperty annotation on the implementation class.
      Parameters:
      metadata - the metadata for which to get the title property, or null.
      Returns:
      the title property value of the given metadata, or null if none.
      See Also:
    • asNameMap

      public Map<String,String> asNameMap(Class<?> type, KeyNamePolicy keyPolicy, KeyNamePolicy valuePolicy) throws ClassCastException
      Returns the names of all properties defined in the given metadata type. The property names appears both as keys and as values, but may be written differently. The names may be standard identifiers (e.g. as defined by ISO 19115), JavaBeans names, method names or sentences (usually in English).
      Example: The following code prints "alternateTitles" (note the plural):
      The keyPolicy argument specify only the string representation of keys returned by the iterators. No matter the key name policy, the key argument given to any Map method can be any of the above-cited forms of property names.
      Parameters:
      type - the interface or implementation class of a metadata.
      keyPolicy - determines the string representation of map keys.
      valuePolicy - determines the string representation of map values.
      Returns:
      the names of all properties defined by the given metadata type.
      Throws:
      ClassCastException - if the specified interface or implementation class does not extend or implement a metadata interface of the expected package.
    • asTypeMap

      public Map<String,Class<?>> asTypeMap(Class<?> type, KeyNamePolicy keyPolicy, TypeValuePolicy valuePolicy) throws ClassCastException
      Returns the type of all properties, or their declaring type, defined in the given metadata type. The keys in the returned map are the same than the keys in the above name map. The values are determined by the valuePolicy argument, which can be element type or the declaring interface among others.
      Example: the following code prints the InternationalString class name:
      Parameters:
      type - the interface or implementation class of a metadata.
      keyPolicy - determines the string representation of map keys.
      valuePolicy - whether the values shall be property types, the element types (same as property types except for collections) or the declaring interface or class.
      Returns:
      the types or declaring type of all properties defined in the given metadata type.
      Throws:
      ClassCastException - if the specified interface or implementation class does not extend or implement a metadata interface of the expected package.
    • asInformationMap

      public Map<String,org.opengis.metadata.ExtendedElementInformation> asInformationMap(Class<?> type, KeyNamePolicy keyPolicy) throws ClassCastException
      Returns information about all properties defined in the given metadata type. The keys in the returned map are the same than the keys in the above name map. The values contain information inferred from the ISO names, the Obligation enumeration and the ValueRange annotations.

      In the particular case of Apache SIS implementation, all values in the information map additionally implement the following interfaces:

      • ReferenceIdentifier with the following properties:
        • The authority is this metadata standard citation.
        • The codespace is the standard name of the interface that contain the property.
        • The code is the standard name of the property.
      • CheckedContainer with the following properties:
      Note: the rational for implementing CheckedContainer is to consider each ExtendedElementInformation instance as the set of all possible values for the property. If the information had a contains(E) method, it would return true if the given value is valid for that property.
      In addition, for each map entry the value returned by ExtendedElementInformation.getDomainValue() may optionally be an instance of any of the following classes:
      • NumberRange if the valid values are constrained to some specific range.
      Parameters:
      type - the metadata interface or implementation class.
      keyPolicy - determines the string representation of map keys.
      Returns:
      information about all properties defined in the given metadata type.
      Throws:
      ClassCastException - if the given type does not implement a metadata interface of the expected package.
      See Also:
    • asIndexMap

      public Map<String,Integer> asIndexMap(Class<?> type, KeyNamePolicy keyPolicy) throws ClassCastException
      Returns indices for all properties defined in the given metadata type. The keys in the returned map are the same than the keys in the above name map. The values are arbitrary indices numbered from 0 inclusive to n exclusive, where n is the number of properties declared in the given metadata type.

      Property indices may be used as an alternative to property names by some applications doing their own storage. Such index usages are fine for temporary storage during the Java Virtual Machine lifetime, but indices should not be used in permanent storage. The indices are stable as long as the metadata implementation does not change, but may change when the implementation is upgraded to a newer version.

      Parameters:
      type - the interface or implementation class of a metadata.
      keyPolicy - determines the string representation of map keys.
      Returns:
      indices of all properties defined by the given metadata type.
      Throws:
      ClassCastException - if the specified interface or implementation class does not extend or implement a metadata interface of the expected package.
    • asValueMap

      public Map<String,Object> asValueMap(Object metadata, Class<?> baseType, KeyNamePolicy keyPolicy, ValueExistencePolicy valuePolicy) throws ClassCastException
      Returns a view of the specified metadata object as a Map. The map is backed by the metadata object using Java reflection, so changes in the underlying metadata object are immediately reflected in the map and conversely.

      The map content is determined by the arguments: metadata determines the set of keys, keyPolicy determines their String representations of those keys and valuePolicy determines whether entries having a null value or an empty collection shall be included in the map.

      Supported operations

      The map supports the put(…) and remove(…) operations if the underlying metadata object contains setter methods. The remove(…) method is implemented by a call to put(…, null). Note that whether the entry appears as effectively removed from the map or just cleared (i.e. associated to a null value) depends on the valuePolicy argument.

      Keys and values

      The keys are case-insensitive and can be either the JavaBeans property name, the getter method name or the UML identifier. The value given to a call to the put(…) method shall be an instance of the type expected by the corresponding setter method, or an instance of a type convertible to the expected type.

      Multi-values entries

      Calls to put(…) replace the previous value, with one noticeable exception: if the metadata property associated to the given key is a Collection but the given value is a single element (not a collection), then the given value is added to the existing collection. In other words, the returned map behaves as a multi-values map for the properties that allow multiple values. If the intent is to unconditionally discard all previous values, then make sure that the given value is a collection when the associated metadata property expects such collection.

      Disambiguating instances that implement more than one metadata interface

      It is some time convenient to implement more than one interface by the same class. For example, an implementation interested only in extents defined by geographic bounding boxes could implement Extent and GeographicBoundingBox by the same class. In such case, it is necessary to tell to this method which one of those two interfaces shall be reflected in the returned map. This information can be provided by the baseType argument. That argument needs to be non-null only in situations where an ambiguity can arise; baseType can be null if the given metadata implements only one interface recognized by this MetadataStandard instance.
      Parameters:
      metadata - the metadata object to view as a map.
      baseType - base type of the metadata of interest, or null if unspecified.
      keyPolicy - determines the string representation of map keys.
      valuePolicy - whether the entries having null value or empty collection shall be included in the map.
      Returns:
      a map view over the metadata object.
      Throws:
      ClassCastException - if the metadata object does not implement a metadata interface of the expected package.
      Since:
      0.8
      See Also:
    • asTreeTable

      public TreeTable asTreeTable(Object metadata, Class<?> baseType, ValueExistencePolicy valuePolicy) throws ClassCastException
      Returns the specified metadata object as a tree table. The tree table is backed by the metadata object using Java reflection, so changes in the underlying metadata object are immediately reflected in the tree table and conversely.

      The returned TreeTable instance contains the following columns:

      • TableColumn.IDENTIFIER
        The UML identifier if any, or the Java Beans property name otherwise, of a metadata property. For example in a tree table view of DefaultCitation, there is a node having the "title" identifier.
      • TableColumn.INDEX
        If the metadata property is a collection, then the zero-based index of the element in that collection. Otherwise null. For example, in a tree table view of DefaultCitation, if the "alternateTitle" collection contains two elements, then there is a node with index 0 for the first element and another node with index 1 for the second element.
        Note: The (IDENTIFIER, INDEX) pair can be used as a primary key for uniquely identifying a node in a list of children. That uniqueness is guaranteed only for the children of a given node; the same keys may appear in the children of any other nodes.
      • TableColumn.NAME
        A human-readable name for the node, derived from the identifier and the index. This is the column shown in the default toString() implementation and may be localizable.
      • TableColumn.TYPE
        The base type of the value (usually an interface).
      • TableColumn.VALUE
        The metadata value for the node. Values in this column are writable if the underlying metadata class have a setter method for the property represented by the node.
      • TableColumn.REMARKS
        Remarks or warning on the property value. This is rarely present. It is provided when the value may look surprising, for example the longitude values in a geographic bounding box crossing the anti-meridian.

      Write operations

      Only the VALUE column may be writable, with one exception: newly created children need to have their IDENTIFIER set before any other operation. For example, the following code adds a title to a citation: Nodes can be removed by invoking the Iterator.remove() method on the children iterator. Note that whether the child appears as effectively removed from the node or just cleared (i.e. associated to a null value) depends on the valuePolicy argument.

      Disambiguating instances that implement more than one metadata interface

      If the given metadata instance implements more than one interface recognized by this MetadataStandard, then the baseType argument need to be non-null in order to specify which interface to reflect in the tree.
      Parameters:
      metadata - the metadata object to view as a tree table.
      baseType - base type of the metadata of interest, or null if unspecified.
      valuePolicy - whether the property having null value or empty collection shall be included in the tree.
      Returns:
      a tree table representation of the specified metadata.
      Throws:
      ClassCastException - if the metadata object does not implement a metadata interface of the expected package.
      Since:
      0.8
      See Also:
    • equals

      public boolean equals(Object metadata1, Object metadata2, ComparisonMode mode) throws ClassCastException
      Compares the two specified metadata objects. The two metadata arguments shall be implementations of a metadata interface defined by this MetadataStandard, otherwise an exception will be thrown. However, the two arguments do not need to be the same implementation class.

      Shallow or deep comparisons

      This method implements a shallow comparison in that properties are compared by invoking their properties.equals(…) method without explicit recursive call to this standard.equals(…) method for children metadata. However, the comparison will do implicit recursive calls if the properties.equals(…) implementations delegate their work to this standard.equals(…) method, as AbstractMetadata does. In the latter case, the final result is a deep comparison.
      Parameters:
      metadata1 - the first metadata object to compare.
      metadata2 - the second metadata object to compare.
      mode - the strictness level of the comparison.
      Returns:
      true if the given metadata objects are equals.
      Throws:
      ClassCastException - if at least one metadata object does not implement a metadata interface of the expected package.
      See Also:
    • hashCode

      public int hashCode(Object metadata) throws ClassCastException
      Computes a hash code for the specified metadata. The hash code is defined as the sum of hash code values of all non-empty properties, plus the hash code of the interface. This is a similar contract than Set.hashCode() (except for the interface) and ensures that the hash code value is insensitive to the ordering of properties.
      Parameters:
      metadata - the metadata object to compute hash code.
      Returns:
      a hash code value for the specified metadata, or 0 if the given metadata is null.
      Throws:
      ClassCastException - if the metadata object does not implement a metadata interface of the expected package.
      See Also:
    • toString

      public String toString()
      Returns a string representation of this metadata standard. This is for debugging purpose only and may change in any future version.
      Overrides:
      toString in class Object
    • setMapForField

      static <T extends MetadataStandard> void setMapForField(Class<T> classe, T instance, String name) throws InvalidClassException
      Assigns a ConcurrentMap instance to the given field. Used on deserialization only.
      Throws:
      InvalidClassException
    • readObject

      private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException
      Invoked during deserialization for restoring the transient fields.
      Parameters:
      in - the input stream from which to deserialize a metadata standard.
      Throws:
      IOException - if an I/O error occurred while reading or if the stream contains invalid data.
      ClassNotFoundException - if the class serialized on the stream is not on the classpath.