com.restfb

Class DefaultJsonMapper

java.lang.Object

com.restfb.DefaultJsonMapper

All Implemented Interfaces:

JsonMapper

public class DefaultJsonMapper
extends Object
implements JsonMapper

Default implementation of a JSON-to-Java mapper.

Author:

Mark Allen

Constructor Summary

Constructors

Constructor and Description
DefaultJsonMapper()

Method Summary

Modifier and Type	Method and Description
protected <T> T	createInstance(Class<T> type) Creates a new instance of the given type.
protected Set<String>	facebookFieldNamesWithMultipleMappings(List<ReflectionUtils.FieldWithAnnotation<Facebook>> fieldsWithAnnotation) Finds any Facebook JSON fields that are mapped to more than 1 Java field.
protected String	getFacebookFieldName(ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation) For a Java field annotated with the Facebook annotation, figure out what the corresponding Facebook JSON field name to map to it is.
protected boolean	isEmptyObject(String json) Is the given JSON equivalent to the empty object ({})?
protected void	logMultipleMappingFailedForField(String facebookFieldName, ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation, String json) Dumps out a log message when one of a multiple-mapped Facebook field name JSON-to-Java mapping operation fails.
<T> List<T>	toJavaList(String json, Class<T> type) Given a JSON string, create and return a new instance of a corresponding Java List which contains elements of type type.
<T> T	toJavaObject(String json, Class<T> type) Given a JSON string, create and return a new instance of a corresponding Java object of type type.
protected Object	toJavaType(ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation, JsonObject jsonObject, String facebookFieldName) Extracts JSON data for a field according to its Facebook annotation and returns it converted to the proper Java type.
String	toJson(Object object) Given a Java object, create and return a JSON string that represents it.
protected Object	toJsonInternal(Object object) Recursively marshal the given object to JSON.
protected <T> T	toPrimitiveJavaType(String json, Class<T> type) Given a json value of something like MyValue or 123 , return a representation of that value of type type.
protected void	verifyThatJsonIsOfObjectType(String json) Is the given json a valid JSON object?

Methods inherited from class java.lang.Object

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

Constructor Detail

DefaultJsonMapper

public DefaultJsonMapper()

Method Detail

toJavaList

public <T> List<T> toJavaList(String json,
                              Class<T> type)

Description copied from interface: JsonMapper

Given a JSON string, create and return a new instance of a corresponding Java List which contains elements of type type.

The Java type must have a visible no-argument constructor.

Specified by:

toJavaList in interface JsonMapper

Type Parameters:

T - Java type to map to for each element of the list.

Parameters:

json - The JSON to be mapped to a Java type.

type - Java type token.

Returns:

A Java object (of type List which contains elements of type type) representation of the JSON input.

See Also:

JsonMapper.toJavaList(String, Class)

toJavaObject

public <T> T toJavaObject(String json,
                          Class<T> type)

Description copied from interface: JsonMapper

Given a JSON string, create and return a new instance of a corresponding Java object of type type.

The Java type must have a visible no-argument constructor.

Specified by:

toJavaObject in interface JsonMapper

Type Parameters:

T - Java type to map to.

Parameters:

json - The JSON to be mapped to a Java type.

type - Java type token.

Returns:

A Java object (of type type) representation of the JSON input.

See Also:

JsonMapper.toJavaObject(String, Class)

logMultipleMappingFailedForField

protected void logMultipleMappingFailedForField(String facebookFieldName,
                                                ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation,
                                                String json)

Dumps out a log message when one of a multiple-mapped Facebook field name JSON-to-Java mapping operation fails.

Parameters:

facebookFieldName - The Facebook field name.

fieldWithAnnotation - The Java field to map to and its annotation.

json - The JSON that failed to map to the Java field.

getFacebookFieldName

protected String getFacebookFieldName(ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation)

For a Java field annotated with the Facebook annotation, figure out what the corresponding Facebook JSON field name to map to it is.

Parameters:

fieldWithAnnotation - A Java field annotated with the Facebook annotation.

Returns:

The Facebook JSON field name that should be mapped to this Java field.

facebookFieldNamesWithMultipleMappings

protected Set<String> facebookFieldNamesWithMultipleMappings(List<ReflectionUtils.FieldWithAnnotation<Facebook>> fieldsWithAnnotation)

Finds any Facebook JSON fields that are mapped to more than 1 Java field.

Parameters:

fieldsWithAnnotation - Java fields annotated with the Facebook annotation.

Returns:

Any Facebook JSON fields that are mapped to more than 1 Java field.

toJson

public String toJson(Object object)

Description copied from interface: JsonMapper

Given a Java object, create and return a JSON string that represents it.

The object's properties will be traversed recursively, allowing for arbitrarily complex JSON generation.

Specified by:

toJson in interface JsonMapper

Parameters:

object - The Java object to map to JSON. Can be a Javabean, List, or Map.

Returns:

A JSON string.

See Also:

JsonMapper.toJson(Object)

verifyThatJsonIsOfObjectType

protected void verifyThatJsonIsOfObjectType(String json)

Is the given json a valid JSON object?

Parameters:

json - The JSON to check.

Throws:

FacebookJsonMappingException - If json is not a valid JSON object.

toJsonInternal

protected Object toJsonInternal(Object object)

Recursively marshal the given object to JSON.

Used by toJson(Object).

Parameters:

object - The object to marshal.

Returns:

JSON representation of the given object.

Throws:

FacebookJsonMappingException - If an error occurs while marshaling to JSON.

toPrimitiveJavaType

protected <T> T toPrimitiveJavaType(String json,
                                    Class<T> type)

Given a json value of something like MyValue or 123 , return a representation of that value of type type.

This is to support non-legal JSON served up by Facebook for API calls like Friends.get (example result: [222333,1240079]).

Type Parameters:

T - The Java type to map to.

Parameters:

json - The non-legal JSON to map to the Java type.

type - Type token.

Returns:

Java representation of json.

Throws:

FacebookJsonMappingException - If an error occurs while mapping JSON to Java.

toJavaType

protected Object toJavaType(ReflectionUtils.FieldWithAnnotation<Facebook> fieldWithAnnotation,
                            JsonObject jsonObject,
                            String facebookFieldName)
                     throws JsonException,
                            FacebookJsonMappingException

Extracts JSON data for a field according to its Facebook annotation and returns it converted to the proper Java type.

Parameters:

fieldWithAnnotation - The field/annotation pair which specifies what Java type to convert to.

jsonObject - "Raw" JSON object to pull data from.

facebookFieldName - Specifies what JSON field to pull "raw" data from.

Returns:

A

Throws:

JsonException - If an error occurs while mapping JSON to Java.

FacebookJsonMappingException - If an error occurs while mapping JSON to Java.

createInstance

protected <T> T createInstance(Class<T> type)

Creates a new instance of the given type.

Type Parameters:

T - Java type to map to.

Parameters:

type - Type token.

Returns:

A new instance of type.

Throws:

FacebookJsonMappingException - If an error occurs when creating a new instance (type is inaccessible, doesn't have a public no-arg constructor, etc.)

isEmptyObject

protected boolean isEmptyObject(String json)

Is the given JSON equivalent to the empty object ({})?

Parameters:

json - The JSON to check.

Returns:

true if the JSON is equivalent to the empty object, false otherwise.