com.mxgraph.io
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 Summary

protected Map<String,Method>	accessors Caches accessors for the given method names.
protected Set<String>	exclude Array containing the variable names that should be ignored by the codec.
protected Map<Class,Map<String,Field>>	fields Caches fields for faster access.
protected Set<String>	idrefs Array containing the variable names that should be turned into or converted from references.
protected Map<String,String>	mapping Maps from from fieldnames to XML attribute names.
protected Map<String,String>	reverse Maps from from XML attribute names to fieldnames.
protected Object	template Holds the template object associated with this codec.

Constructor Summary

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

mxObjectCodec(Object template, String[] exclude, String[] idrefs, Map<String,String> mapping)
Constructs a new codec for the specified template object.

Method Summary

protected void	addObjectValue(Object obj, String fieldname, Object value, Object template) Sets the decoded child node as a value of the given object.
Object	afterDecode(mxCodec dec, Node node, Object obj) Hook for subclassers to post-process the object after decoding.
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.
Node	beforeDecode(mxCodec dec, Node node, Object obj) Hook for subclassers to pre-process the node for the specified object and return the node to be used for further processing by decode(mxCodec, Node).
Object	beforeEncode(mxCodec enc, Object obj, Node node) Hook for subclassers to pre-process the object before encoding.
protected Object	cloneTemplate(Node node) Returns a new instance of the template object for representing the given node.
protected Object	convertValueFromXml(Class<?> type, Object value) Converts XML attribute values to object of the given type.
protected Object	convertValueToXml(Object value) Converts true to "1" and false to "0".
Object	decode(mxCodec dec, Node node) Parses the given node into the object or returns a new object representing the given node.
Object	decode(mxCodec dec, Node node, Object into) Parses the given node into the object or returns a new object representing the given node.
protected void	decodeAttribute(mxCodec dec, Node attr, Object obj) Reads the given attribute into the specified object.
protected void	decodeAttributes(mxCodec dec, Node node, Object obj) Decodes all attributes of the given node using decodeAttribute.
protected void	decodeChild(mxCodec dec, Node child, Object obj) Reads the specified child into the given object.
protected void	decodeChildren(mxCodec dec, Node node, Object obj) Decodec all children of the given node using decodeChild.
protected void	decodeNode(mxCodec dec, Node node, Object obj) Calls decodeAttributes and decodeChildren for the given node.
Node	encode(mxCodec enc, Object obj) Encodes the specified object and returns a node representing then given object.
protected void	encodeElements(mxCodec enc, Object obj, Node node) Encodes the child objects of arrays, maps and collections.
protected void	encodeFields(mxCodec enc, Object obj, Node node) Encodes the declared fields of the given object into the given node.
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).
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.
protected Method	getAccessor(Object obj, Field field, boolean isGetter) Returns the accessor (getter, setter) for the specified field.
protected String	getAttributeName(String fieldname) Returns the XML node attribute name for the given Java field name.
protected Field	getField(Object obj, String fieldname) Returns the field with the specified name.
protected String	getFieldName(String attributename) Returns the Java field name for the given XML attribute name.
protected Object	getFieldTemplate(Object obj, String fieldname, Node child) Returns the template instance for the given field.
protected Object	getFieldValue(Object obj, String fieldname) Returns the value of the field with the specified name in the specified object instance.
protected Object	getFieldValueWithAccessor(Object obj, Field field) Returns the value of the field using the accessor for the field if one exists.
protected Method	getMethod(Object obj, String methodname, Class[] params) Returns the method with the specified signature.
String	getName() Returns the name used for the nodenames and lookup of the codec when classes are encoded and nodes are decoded.
Object	getTemplate() Returns the template object associated with this codec.
boolean	isExcluded(Object obj, String attr, Object value, boolean write) Returns true if the given attribute is to be ignored by the codec.
protected boolean	isPrimitiveValue(Object value) Returns true if the given object is a primitive value.
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).
boolean	processInclude(mxCodec dec, Node node, Object into) Returns true if the given node is an include directive and executes the include by decoding the XML document.
protected void	setFieldValue(Object obj, String fieldname, Object value) Sets the value of the field with the specified name in the specified object instance.
protected void	setFieldValueWithAccessor(Object obj, Field field, Object value) Sets the value of the given field using the accessor if one exists.
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.
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.
protected void	writePrimitiveAttribute(mxCodec enc, Object obj, String attr, Object value, Node node) Writes the given value as an attribute of the given node.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

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 and .

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 Detail

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 Detail

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 printed to System.err.

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