Class mxObjectCodec

java.lang.Object
com.mxgraph.io.mxObjectCodec
Direct Known Subclasses:
mxCellCodec, mxChildChangeCodec, mxGenericChangeCodec, mxModelCodec, mxRootChangeCodec, mxStylesheetCodec, mxTerminalChangeCodec

public class mxObjectCodec extends Object
Generic codec for Java objects. See below for a detailed description of the encoding/decoding scheme. Note: Since booleans are numbers in JavaScript, all boolean values are encoded into 1 for true and 0 for false.
  • Field Details

    • template

      protected Object template
      Holds the template object associated with this codec.
    • exclude

      protected Set<String> exclude
      Array containing the variable names that should be ignored by the codec.
    • idrefs

      protected Set<String> idrefs
      Array containing the variable names that should be turned into or converted from references. See invalid input: '<'mxCodec.getId> and invalid input: '<'mxCodec.getObject>.
    • mapping

      protected Map<String,String> mapping
      Maps from from fieldnames to XML attribute names.
    • reverse

      protected Map<String,String> reverse
      Maps from from XML attribute names to fieldnames.
    • accessors

      protected Map<String,Method> accessors
      Caches accessors for the given method names.
    • fields

      protected Map<Class,Map<String,Field>> fields
      Caches fields for faster access.
  • Constructor Details

    • mxObjectCodec

      public mxObjectCodec(Object template)
      Constructs a new codec for the specified template object.
    • mxObjectCodec

      public mxObjectCodec(Object template, String[] exclude, String[] idrefs, Map<String,String> mapping)
      Constructs a new codec for the specified template object. The variables in the optional exclude array are ignored by the codec. Variables in the optional idrefs array are turned into references in the XML. The optional mapping may be used to map from variable names to XML attributes. The argument is created as follows:
      Parameters:
      template - Prototypical instance of the object to be encoded/decoded.
      exclude - Optional array of fieldnames to be ignored.
      idrefs - Optional array of fieldnames to be converted to/from references.
      mapping - Optional mapping from field- to attributenames.
  • Method Details

    • getName

      public String getName()
      Returns the name used for the nodenames and lookup of the codec when classes are encoded and nodes are decoded. For classes to work with this the codec registry automatically adds an alias for the classname if that is different than what this returns. The default implementation returns the classname of the template class. Here is an example on how to use this for renaming mxCell nodes: mxCodecRegistry.register(new mxCellCodec() { public String getName() { return "anotherName"; } });
    • getTemplate

      public Object getTemplate()
      Returns the template object associated with this codec.
      Returns:
      Returns the template object.
    • cloneTemplate

      protected Object cloneTemplate(Node node)
      Returns a new instance of the template object for representing the given node.
      Parameters:
      node - XML node that the object is going to represent.
      Returns:
      Returns a new template instance.
    • isExcluded

      public boolean isExcluded(Object obj, String attr, Object value, boolean write)
      Returns true if the given attribute is to be ignored by the codec. This implementation returns true if the given fieldname is in exclude.
      Parameters:
      obj - Object instance that contains the field.
      attr - Fieldname of the field.
      value - Value of the field.
      write - Boolean indicating if the field is being encoded or decoded. write is true if the field is being encoded, else it is being decoded.
      Returns:
      Returns true if the given attribute should be ignored.
    • isReference

      public boolean isReference(Object obj, String attr, Object value, boolean isWrite)
      Returns true if the given fieldname is to be treated as a textual reference (ID). This implementation returns true if the given fieldname is in idrefs.
      Parameters:
      obj - Object instance that contains the field.
      attr - Fieldname of the field.
      value - Value of the field.
      isWrite - Boolean indicating if the field is being encoded or decoded. isWrite is true if the field is being encoded, else it is being decoded.
      Returns:
      Returns true if the given attribute should be handled as a reference.
    • encode

      public Node encode(mxCodec enc, Object obj)
      Encodes the specified object and returns a node representing then given object. Calls beforeEncode after creating the node and afterEncode with the resulting node after processing. Enc is a reference to the calling encoder. It is used to encode complex objects and create references. This implementation encodes all variables of an object according to the following rules:
      • If the variable name is in exclude then it is ignored.
      • If the variable name is in idrefs then mxCodec.getId(Object) is used to replace the object with its ID.
      • The variable name is mapped using mapping.
      • If obj is an array and the variable name is numeric (ie. an index) then it is not encoded.
      • If the value is an object, then the codec is used to create a child node with the variable name encoded into the "as" attribute.
      • Else, if mxCodec.isEncodeDefaults() is true or the value differs from the template value, then ...
        • ... if obj is not an array, then the value is mapped to an attribute.
        • ... else if obj is an array, the value is mapped to an add child with a value attribute or a text child node, if the value is a function.
      If no ID exists for a variable in idrefs or if an object cannot be encoded, a warning is logged.
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object to be encoded.
      Returns:
      Returns the resulting XML node that represents the given object.
    • encodeObject

      protected void encodeObject(mxCodec enc, Object obj, Node node)
      Encodes the value of each member in then given obj into the given node using encodeFields(mxCodec, Object, Node) and encodeElements(mxCodec, Object, Node).
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object to be encoded.
      node - XML node that contains the encoded object.
    • encodeFields

      protected void encodeFields(mxCodec enc, Object obj, Node node)
      Encodes the declared fields of the given object into the given node.
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object whose fields should be encoded.
      node - XML node that contains the encoded object.
    • encodeElements

      protected void encodeElements(mxCodec enc, Object obj, Node node)
      Encodes the child objects of arrays, maps and collections.
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object whose child objects should be encoded.
      node - XML node that contains the encoded object.
    • encodeValue

      protected void encodeValue(mxCodec enc, Object obj, String fieldname, Object value, Node node)
      Converts the given value according to the mappings and id-refs in this codec and uses writeAttribute(mxCodec, Object, String, Object, Node) to write the attribute into the given node.
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object whose field is going to be encoded.
      fieldname - Name if the field to be encoded.
      value - Value of the property to be encoded.
      node - XML node that contains the encoded object.
    • isPrimitiveValue

      protected boolean isPrimitiveValue(Object value)
      Returns true if the given object is a primitive value.
      Parameters:
      value - Object that should be checked.
      Returns:
      Returns true if the given object is a primitive value.
    • writeAttribute

      protected void writeAttribute(mxCodec enc, Object obj, String attr, Object value, Node node)
      Writes the given value into node using writePrimitiveAttribute or writeComplexAttribute depending on the type of the value.
    • writePrimitiveAttribute

      protected void writePrimitiveAttribute(mxCodec enc, Object obj, String attr, Object value, Node node)
      Writes the given value as an attribute of the given node.
    • writeComplexAttribute

      protected void writeComplexAttribute(mxCodec enc, Object obj, String attr, Object value, Node node)
      Writes the given value as a child node of the given node.
    • convertValueToXml

      protected Object convertValueToXml(Object value)
      Converts true to "1" and false to "0". All other values are ignored.
    • convertValueFromXml

      protected Object convertValueFromXml(Class<?> type, Object value)
      Converts XML attribute values to object of the given type.
    • getAttributeName

      protected String getAttributeName(String fieldname)
      Returns the XML node attribute name for the given Java field name. That is, it returns the mapping of the field name.
    • getFieldName

      protected String getFieldName(String attributename)
      Returns the Java field name for the given XML attribute name. That is, it returns the reverse mapping of the attribute name.
      Parameters:
      attributename - The attribute name to be mapped.
      Returns:
      String that represents the mapped field name.
    • getField

      protected Field getField(Object obj, String fieldname)
      Returns the field with the specified name.
    • getAccessor

      protected Method getAccessor(Object obj, Field field, boolean isGetter)
      Returns the accessor (getter, setter) for the specified field.
    • getMethod

      protected Method getMethod(Object obj, String methodname, Class[] params)
      Returns the method with the specified signature.
    • getFieldValue

      protected Object getFieldValue(Object obj, String fieldname)
      Returns the value of the field with the specified name in the specified object instance.
    • getFieldValueWithAccessor

      protected Object getFieldValueWithAccessor(Object obj, Field field)
      Returns the value of the field using the accessor for the field if one exists.
    • setFieldValue

      protected void setFieldValue(Object obj, String fieldname, Object value)
      Sets the value of the field with the specified name in the specified object instance.
    • setFieldValueWithAccessor

      protected void setFieldValueWithAccessor(Object obj, Field field, Object value)
      Sets the value of the given field using the accessor if one exists.
    • beforeEncode

      public Object beforeEncode(mxCodec enc, Object obj, Node node)
      Hook for subclassers to pre-process the object before encoding. This returns the input object. The return value of this function is used in encode to perform the default encoding into the given node.
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object to be encoded.
      node - XML node to encode the object into.
      Returns:
      Returns the object to be encoded by the default encoding.
    • afterEncode

      public Node afterEncode(mxCodec enc, Object obj, Node node)
      Hook for subclassers to post-process the node for the given object after encoding and return the post-processed node. This implementation returns the input node. The return value of this method is returned to the encoder from . Parameters:
      Parameters:
      enc - Codec that controls the encoding process.
      obj - Object to be encoded.
      node - XML node that represents the default encoding.
      Returns:
      Returns the resulting node of the encoding.
    • decode

      public Object decode(mxCodec dec, Node node)
      Parses the given node into the object or returns a new object representing the given node.
      Parameters:
      dec - Codec that controls the encoding process.
      node - XML node to be decoded.
      Returns:
      Returns the resulting object that represents the given XML node.
    • decode

      public Object decode(mxCodec dec, Node node, Object into)
      Parses the given node into the object or returns a new object representing the given node. Dec is a reference to the calling decoder. It is used to decode complex objects and resolve references. If a node has an id attribute then the object cache is checked for the object. If the object is not yet in the cache then it is constructed using the constructor of