org.eel.kitchen.jsonschema.ref

Class JsonRef

java.lang.Object

org.eel.kitchen.jsonschema.ref.JsonRef

public final class JsonRef
extends Object

Representation of a JSON Reference

JSON Reference, currently a draft, is a way to address a JSON instance of whatever type.

To quote the draft, "A JSON Reference is a JSON object, which contains a member named "$ref", which has a JSON string value." This string value must be a URI. Example:

     {
         "$ref": "http://example.com/example.json#/foo/bar"
     }
 

Here we choose to derive a little from the specification and calculate references from any field, not just $ref. This class is also used, for instance, to compute id.

The implementation is a wrapper over Java's URI, with the following differences:

• all URIs are normalized from the get go;
• an empty fragment is equivalent to no fragment at all, and stands for a root JSON Pointer;
• a reference is taken to be absolute if the underlying URI is absolute and it has no fragment, or an empty fragment.

Field Summary

Fields

Modifier and Type	Field and Description
private static JsonRef	EMPTY An empty JSON Reference
private static URI	EMPTY_URI Empty URI
private JsonFragment	fragment The fragment of this JSON Reference
private static URI	HASHONLY_URI URI with only an empty fragment part
private URI	locator The locator for this fragment
private URI	uri The URI, as provided by the input, with an appended empty fragment if no fragment was provided

Constructor Summary

Constructors

Modifier	Constructor and Description
private	JsonRef(URI uri) The main constructor, which is private by design

Method Summary

Methods

Modifier and Type	Method and Description
boolean	contains(JsonRef other) Tell whether the current JSON Reference contains another
static JsonRef	emptyRef() Return an empty reference
boolean	equals(Object obj)
static JsonRef	fromNode(JsonNode node) Build a JSON Reference from a JsonNode
static JsonRef	fromString(String s) Build a JSON Reference from a string input
static JsonRef	fromURI(URI uri) Build a JSON Reference from a URI
JsonFragment	getFragment() Return this JSON Reference's fragment
URI	getRootAsURI() Return this JSON Reference's locator
int	hashCode()
boolean	isAbsolute() Tell whether this reference is an absolute reference
JsonRef	resolve(JsonRef other) Resolve this reference against another reference
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

HASHONLY_URI

private static final URI HASHONLY_URI

URI with only an empty fragment part

EMPTY_URI

private static final URI EMPTY_URI

Empty URI

EMPTY

private static final JsonRef EMPTY

An empty JSON Reference

uri

private final URI uri

The URI, as provided by the input, with an appended empty fragment if no fragment was provided

locator

private final URI locator

The locator for this fragment

fragment

private final JsonFragment fragment

The fragment of this JSON Reference

Constructor Detail

JsonRef

private JsonRef(URI uri)

The main constructor, which is private by design

If the provided URI has no fragment, then an empty one is appended.

Parameters:

uri - Input URI

Method Detail

fromURI

public static JsonRef fromURI(URI uri)

Build a JSON Reference from a URI

Parameters:

uri - the provided URI

Returns:

the JSON Reference

Throws:

NullPointerException - the provided URI is null

See Also:

JsonRef(URI)

fromString

public static JsonRef fromString(String s)
                          throws JsonSchemaException

Build a JSON Reference from a string input

Parameters:

s - the string

Returns:

the reference

Throws:

JsonSchemaException - string is not a valid URI

NullPointerException - provided string is null

fromNode

public static JsonRef fromNode(JsonNode node)
                        throws JsonSchemaException

Build a JSON Reference from a JsonNode

If the node is not textual, this returns an empty reference. Otherwise, it calls fromString(String) with this node's text value.

Parameters:

node - the node

Returns:

the reference

Throws:

JsonSchemaException - see fromString(String)

NullPointerException - provided node is null

emptyRef

public static JsonRef emptyRef()

Return an empty reference

An empty reference is a reference which only has an empty fragment.

Returns:

see above

isAbsolute

public boolean isAbsolute()

Tell whether this reference is an absolute reference

A JSON Reference is considered absolute iif the underlying URI is itself absolute and it has an empty, or no, fragment part.

Returns:

see above

resolve

public JsonRef resolve(JsonRef other)

Resolve this reference against another reference

Parameters:

other - the reference to resolve

Returns:

a new reference

getRootAsURI

public URI getRootAsURI()

Return this JSON Reference's locator

The locator of a fragment is the URI with an empty fragment.

Returns:

an URI

getFragment

public JsonFragment getFragment()

Return this JSON Reference's fragment

Returns:

the fragment

contains

public boolean contains(JsonRef other)

Tell whether the current JSON Reference contains another

This is considered true iif both references have the same locator, in other words, if they differ only by their fragment part.

Parameters:

other - the other reference

Returns:

see above

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object