Module: Java

Defined in:

lib/javaobs.rb

Overview

Java Objects namespace to read and write Java serialized objects to streams. Any Java serialized object can be read from a stream. To write a Java object, the meta class must be primed with a sample input serialized object. The is required because Java uses a UUID to identify classes and it is generated using a complex hashing scheme of data and method signatures. Since this system does not have access to that information, it needs to get it from a serialized object.

Objects that have custom serialization methods can be read and written by creating a class as we have for the Date class:

module Java
  module Util
    class Date < SimpleDelegator
      extend JavaObject

      def initialize
        super(Time)
      end

      # Set the time with a Time object.
      def time=(time)
        __setobj__(time)
      end

      def _readJavaData(stream)
        data = stream.readBlockData
        t, = data.unpack("Q")
        __setobj__(Time.at(t / 1000, (t % 1000) * 1000))
      end

      # Get the data in the form needed for the Java date serialization.
      def _writeJavaData(stream)
        t = __getobj__.tv_sec * 1000 + __getobj__.tv_usec / 1000
        stream.writeBlockData([t].pack("Q"))
      end
    end
  end
end

The important methods are the data method that is used for writing the the object to a stream.

All other classes will be auto-generated when the stream is read and persisted. A Java Meta Class is added to the Ruby Class that contains all the Java field information needed to serialize the objects.

Defined Under Namespace

Modules: JavaObject, ObjectStream, Util Classes: JavaArray, JavaClass, JavaField, ObjectInputStream, ObjectOutputStream, SerializationError