Class CycleStrategy

java.lang.Object
org.simpleframework.xml.strategy.CycleStrategy
All Implemented Interfaces:
Strategy

public class CycleStrategy extends Object implements Strategy
The CycleStrategy represents a strategy that is used to augment the deserialization and serialization process such that cycles in an object graph can be supported. This adds additional attributes to the serialized XML elements so that during the deserialization process an objects cycles can be created. Without the use of a strategy such as this, cycles could cause an infinite loop during the serialization process while traversing the graph.
 
    <root id="1">
       <object id="2">
          <object id="3" name="name">Example</item>
          <object reference="2"/>
       </object>
    </root>
 
 
In the above serialized XML there is a circular reference, where the XML element with id "2" contains a reference to itself. In most data binding frameworks this will cause an infinite loop, or in some cases will just fail to represent the references well. With this strategy you can ensure that cycles in complex object graphs will be maintained and can be serialized safely.
See Also:
  • Field Details

    • write

      private final WriteState write
      This is used to maintain session state for writing the graph.
    • read

      private final ReadState read
      This is used to maintain session state for reading the graph.
    • contract

      private final Contract contract
      This is used to provide the names of the attributes to use.
  • Constructor Details

    • CycleStrategy

      public CycleStrategy()
      Constructor for the CycleStrategy object. This is used to create a strategy with default values. By default the values used are "id" and "reference". These values will be added to XML elements during the serialization process. And will be used to deserialize the object cycles fully.
    • CycleStrategy

      public CycleStrategy(String mark, String refer)
      Constructor for the CycleStrategy object. This is used to create a strategy with the specified attributes, which will be added to serialized XML elements. These attributes are used to serialize the objects in such a way the cycles in the object graph can be deserialized and used fully.
      Parameters:
      mark - this is used to mark the identity of an object
      refer - this is used to refer to an existing object
    • CycleStrategy

      public CycleStrategy(String mark, String refer, String label)
      Constructor for the CycleStrategy object. This is used to create a strategy with the specified attributes, which will be added to serialized XML elements. These attributes are used to serialize the objects in such a way the cycles in the object graph can be deserialized and used fully.
      Parameters:
      mark - this is used to mark the identity of an object
      refer - this is used to refer to an existing object
      label - this is used to specify the class for the field
    • CycleStrategy

      public CycleStrategy(String mark, String refer, String label, String length)
      Constructor for the CycleStrategy object. This is used to create a strategy with the specified attributes, which will be added to serialized XML elements. These attributes are used to serialize the objects in such a way the cycles in the object graph can be deserialized and used fully.
      Parameters:
      mark - this is used to mark the identity of an object
      refer - this is used to refer to an existing object
      label - this is used to specify the class for the field
      length - this is the length attribute used for arrays
  • Method Details

    • read

      public Value read(Type type, NodeMap node, Map map) throws Exception
      This method is used to read an object from the specified node. In order to get the root type the field and node map are specified. The field represents the annotated method or field within the deserialized object. The node map is used to get the attributes used to describe the objects identity, or in the case of an existing object it contains an object reference.
      Specified by:
      read in interface Strategy
      Parameters:
      type - the method or field in the deserialized object
      node - this is the XML element attributes to read
      map - this is the session map used for deserialization
      Returns:
      this returns an instance to insert into the object
      Throws:
      Exception - thrown if the class cannot be resolved
    • write

      public boolean write(Type type, Object value, NodeMap node, Map map)
      This is used to write the reference in to the XML element that is to be written. This will either insert an object identity if the object has not previously been written, or, if the object has already been written in a previous element, this will write the reference to that object. This allows all cycles within the graph to be serialized so that they can be fully deserialized.
      Specified by:
      write in interface Strategy
      Parameters:
      type - the type of the field or method in the object
      value - this is the actual object that is to be written
      node - this is the XML element attribute map to use
      map - this is the session map used for the serialization
      Returns:
      returns true if the object has been fully serialized