public class JsonBuilder extends GroovyObjectSupport
A builder for creating JSON payloads.
This builder supports the usual builder syntax made of nested method calls and closures, but also some specific aspects of JSON data structures, such as list of values, etc. Please make sure to have a look at the various methods provided by this builder to be able to learn about the various possibilities of usage.
Example:
def builder = new groovy.json.JsonBuilder()
def root = builder.people {
person {
firstName 'Guillame'
lastName 'Laforge'
// Named arguments are valid values for objects too
address(
city: 'Paris',
country: 'France',
zip: 12345,
)
married true
// a list of values
conferences 'JavaOne', 'Gr8conf'
}
}
// creates a data structure made of maps (Json object) and lists (Json array)
assert root instanceof Map
assert builder.toString() == '{"people":{"person":{"firstName":"Guillame","lastName":"Laforge","address":{"city":"Paris","country":"France","zip":12345},"married":true,"conferences":["JavaOne","Gr8conf"]}}}'
Constructor and description |
---|
JsonBuilder
() Instantiates a JSON builder. |
JsonBuilder
(JsonGenerator generator) Instantiates a JSON builder with a configured generator. |
JsonBuilder
(Object content) Instantiates a JSON builder with some existing data structure. |
JsonBuilder
(Object content, JsonGenerator generator) Instantiates a JSON builder with some existing data structure and a configured generator. |
Type Params | Return Type | Name and description |
---|---|---|
|
Object |
call(Map m) Named arguments can be passed to the JSON builder instance to create a root JSON object |
|
Object |
call(List l) A list of elements as arguments to the JSON builder creates a root JSON array |
|
Object |
call(Object args) Varargs elements as arguments to the JSON builder create a root JSON array |
|
Object |
call(Iterable coll, Closure c) A collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection |
|
Object |
call(Collection coll, Closure c) Delegates to call(Iterable, Closure) |
|
Object |
call(Closure c) A closure passed to a JSON builder will create a root JSON object |
|
Object |
getContent() |
|
Object |
invokeMethod(String name, Object args) A method call on the JSON builder instance will create a root object with only one key whose name is the name of the method being called. |
|
String |
toPrettyString() Pretty-prints and formats the JSON payload. |
|
String |
toString() Serializes the internal data structure built with the builder to a conformant JSON payload string |
|
Writer |
writeTo(Writer out) The JSON builder implements the Writable interface,
so that you can have the builder serialize itself the JSON payload to a writer. |
Methods inherited from class | Name |
---|---|
class GroovyObjectSupport |
getMetaClass, setMetaClass |
Instantiates a JSON builder.
Instantiates a JSON builder with a configured generator.
generator
- used to generate the outputInstantiates a JSON builder with some existing data structure.
content
- a pre-existing data structureInstantiates a JSON builder with some existing data structure and a configured generator.
content
- a pre-existing data structuregenerator
- used to generate the outputNamed arguments can be passed to the JSON builder instance to create a root JSON object
Example:
def json = new groovy.json.JsonBuilder()
json name: "Guillaume", age: 33
assert json.toString() == '{"name":"Guillaume","age":33}'
m
- a map of key / value pairsA list of elements as arguments to the JSON builder creates a root JSON array
Example:
def json = new groovy.json.JsonBuilder()
def result = json([1, 2, 3])
assert result instanceof List
assert json.toString() == "[1,2,3]"
l
- a list of valuesVarargs elements as arguments to the JSON builder create a root JSON array
Example:
def json = new groovy.json.JsonBuilder()
def result = json 1, 2, 3
assert result instanceof List
assert json.toString() == "[1,2,3]"
args
- an array of valuesA collection and closure passed to a JSON builder will create a root JSON array applying the closure to each object in the collection
Example:
class Author {
String name
}
def authors = [new Author (name: "Guillaume"), new Author (name: "Jochen"), new Author (name: "Paul")]
def json = new groovy.json.JsonBuilder()
json authors, { Author author ->
name author.name
}
assert json.toString() == '[{"name":"Guillaume"},{"name":"Jochen"},{"name":"Paul"}]'
coll
- a collectionc
- a closure used to convert the objects of collDelegates to call(Iterable, Closure)
A closure passed to a JSON builder will create a root JSON object
Example:
def json = new groovy.json.JsonBuilder()
def result = json {
name "Guillaume"
age 33
}
assert result instanceof Map
assert json.toString() == '{"name":"Guillaume","age":33}'
c
- a closure whose method call statements represent key / values of a JSON objectA method call on the JSON builder instance will create a root object with only one key whose name is the name of the method being called. This method takes as arguments:
Example with a classical builder-style:
def json = new groovy.json.JsonBuilder()
def result = json.person {
name "Guillaume"
age 33
}
assert result instanceof Map
assert json.toString() == '{"person":{"name":"Guillaume","age":33}}'
Or alternatively with a method call taking named arguments:
def json = new groovy.json.JsonBuilder()
json.person name: "Guillaume", age: 33
assert json.toString() == '{"person":{"name":"Guillaume","age":33}}'
If you use named arguments and a closure as last argument,
the key/value pairs of the map (as named arguments)
and the key/value pairs represented in the closure
will be merged together —
the closure properties overriding the map key/values
in case the same key is used.
def json = new groovy.json.JsonBuilder()
json.person(name: "Guillaume", age: 33) { town "Paris" }
assert json.toString() == '{"person":{"name":"Guillaume","age":33,"town":"Paris"}}'
The empty args call will create a key whose value will be an empty JSON object:
def json = new groovy.json.JsonBuilder()
json.person()
assert json.toString() == '{"person":{}}'
name
- the single keyargs
- the value associated with the keyPretty-prints and formats the JSON payload.
This method calls the JsonLexer to parser the output of the builder, so this may not be an optimal method to call, and should be used mainly for debugging purpose for a human-readable output of the JSON content.
Serializes the internal data structure built with the builder to a conformant JSON payload string
Example:
def json = new groovy.json.JsonBuilder()
json { temperature 37 }
assert json.toString() == '{"temperature":37}'
The JSON builder implements the Writable
interface,
so that you can have the builder serialize itself the JSON payload to a writer.
Example:
def json = new groovy.json.JsonBuilder()
json { temperature 37 }
def out = new StringWriter()
out <<
json
assert out.toString() == '{"temperature":37}'
out
- a writer on which to serialize the JSON payloadCopyright © 2003-2020 The Apache Software Foundation. All rights reserved.