Package org.apache.uima.json

Class JsonCasSerializer

java.lang.Object
org.apache.uima.json.JsonCasSerializer
public class JsonCasSerializer extends Object

CAS serializer for JSON formats.

Writes a CAS in a JSON format.

To use,

  • create an instance of this class,
  • (optionally) configure the instance, and then
  • call serialize on the instance, optionally passing in additional parameters.

After the 1st 2 steps, the serializer instance may be used for multiple calls (on multiple threads) to the 3rd serialize step, if all calls use the same configuration.

There are "convenience" static serialize methods that do these three steps for common configurations.

Parameters can be configured in this instance (I), and/or as part of the serialize(S) call.

The parameters that can be configured are:

  • (S) The CAS to serialize
  • (S) where to put the output - an OutputStream, Writer, or File
  • (I,S) a type system - (default null) if supplied, it is used to "filter" types and features that are serialized. If provided, only those that exist in the passed in type system are included in the serialization
  • (I,S) a flag for prettyprinting - default false (no prettyprinting)

For Json serialization, additional configuration from the Jackson implementation can be configured

on 2 associated Jackson instances:
  • JsonFactory
  • JsonGenerator
using the standard Jackson methods on the associated JsonFactory instance; see the Jackson JsonFactory and JsonGenerator javadocs for details.

These 2 Jackson objects are settable/gettable from an instance of this class. They are created if not supplied by the caller.

Once this instance is configured, the serialize method is called to serialized a CAS to an output.

Instances of this class must be used on only one thread while configuration is being done; afterwards, multiple threads may use the configured instance, to call serialize.

  • Constructor Details

    • JsonCasSerializer

      public JsonCasSerializer()
      Creates a new JsonCasSerializer

  • Method Details

    • jsonSerialize

      public static void jsonSerialize(CAS aCAS, Object output) throws IOException
      Serializes a CAS using JSON
      Parameters:
      aCAS - CAS to serialize.
      output - a File, OutputStream or Writer to which to write the XMI document
      Throws:
      IOException - if there was an IOException

    • jsonSerialize

      public static void jsonSerialize(CAS aCAS, TypeSystem aTargetTypeSystem, Object output) throws IOException
      Serializes a CAS to an output (File, OutputStream, XMI stream, or Writer). The supplied typesystem filters the output
      Parameters:
      aCAS - CAS to serialize.
      aTargetTypeSystem - type system used for filtering what gets serialized. Any types or features not in the target type system will not be serialized. A null value indicates no filtering, that is, that all types and features will be serialized.
      output - output (File, OutputStream, or Writer) to which to write the JSON document
      Throws:
      IOException - if there was an IOException

    • jsonSerialize

      public static void jsonSerialize(CAS aCAS, TypeSystem aTargetTypeSystem, Object output, boolean aPrettyPrint, Marker aMarker, XmiSerializationSharedData sharedData) throws IOException
      Serializes a Delta CAS to an output (File, Writer, or OutputStream). This version of this method allows many options to be configured.
      Parameters:
      aCAS - CAS to serialize.
      aTargetTypeSystem - type system to which the produced XMI will conform. Any types or features not in the target type system will not be serialized. A null value indicates that all types and features will be serialized.
      output - File, Writer, or OutputStream to which to write the JSON document
      aPrettyPrint - if true the JSON output will be formatted with newlines and indenting. If false it will be unformatted.
      aMarker - an optional object used to determine which FeatureStructures and modifications were created after the mark was set. Used to serialize a Delta CAS consisting of only new FSs and views and preexisting FSs and Views that have been modified. If null, full serialization is done. See the JavaDocs for Marker for details.
      sharedData - optional, used for delta serialization (not yet supported)
      Throws:
      IOException - if there was an IOException

    • serialize

      public void serialize(CAS cas, Object output) throws IOException
      Serialize a Cas to an Output, using configurations set on this instance. Constructs a JsonContentHandlerJacksonWrapper, using configured JsonFactory and prettyprint settings if any
      Parameters:
      cas - - the CAS to serialize
      output - - where the output goes, an OutputStream, Writer, or File
      Throws:
      IOException - if there was an IOException

    • serialize

      public void serialize(CAS cas, Object output, XmiSerializationSharedData sharedData, Marker marker) throws IOException
      Throws:
      IOException

    • serialize

      public void serialize(CAS cas, JsonContentHandlerJacksonWrapper jch) throws IOException
      Serialize a Cas to an Output configured in the passed in JsonContentHandlerJacksonWrapper Constructs a new CasDocSerializer instance to do the serialization, configured using this class's Delta marker setting (if any)
      Parameters:
      cas - The CAS to serialize
      jch - the configured content handler
      Throws:
      IOException - if there was an IOException

    • serialize

      public void serialize(CAS cas, JsonContentHandlerJacksonWrapper jch, XmiSerializationSharedData sharedData, Marker marker) throws IOException
      Throws:
      IOException

    • setPrettyPrint

      public JsonCasSerializer setPrettyPrint(boolean pp)
      set or reset the pretty print flag (default is false)
      Parameters:
      pp - true to do pretty printing of output
      Returns:
      the original instance, possibly updated

    • setJsonFactory

      public JsonCasSerializer setJsonFactory(com.fasterxml.jackson.core.JsonFactory jsonFactory)
      set which JsonFactory instance to use; if null, a new instance is used this can be used to preconfigure the JsonFactory instance
      Parameters:
      jsonFactory - -
      Returns:
      the original instance, possibly updated

    • setFilterTypes

      public JsonCasSerializer setFilterTypes(TypeSystemImpl ts)
      pass in a type system to use for filtering what gets serialized; only those types and features which are defined this type system are included.
      Parameters:
      ts - the filter
      Returns:
      the original instance, possibly updated

    • setTypeSystemReference

      public JsonCasSerializer setTypeSystemReference(String reference)

    • setErrorHandler

      public JsonCasSerializer setErrorHandler(ErrorHandler eh)
      set an error handler to receive information about errors
      Parameters:
      eh - the error handler
      Returns:
      the original instance, possibly updated

    • setStaticEmbedding

      public JsonCasSerializer setStaticEmbedding()
      Sets static embedding mode
      Returns:
      the original instance, possibly updated

    • setJsonContext

      public JsonCasSerializer setJsonContext(JsonCasSerializer.JsonContextFormat format)
      sets which Json context format to use when serializing
      Parameters:
      format - the format to use for the serialization Specifying the context flag also specifies all 3 subflags Specifying one of the subflags as true sets the context flag to true if it isn't already
      Returns:
      the original instance, possibly updated

    • setOmit0Values

      public JsonCasSerializer setOmit0Values(boolean omitDefaultValues)