public class JsonBuilder extends GroovyObjectSupport implements Writable
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(Object content)
Instantiates a JSON builder with some existing data structure.
|
Modifier and Type | Method and Description |
---|---|
Object |
call(Closure c)
A closure passed to a JSON builder will create a root JSON object
|
Object |
call(Collection 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(List l)
A list of elements as arguments to the JSON builder creates a root JSON array
|
Object |
call(Map m)
Named arguments can be passed to the JSON builder instance to create a root JSON object
|
Object |
call(Object... args)
Varargs elements as arguments to the JSON builder create a root JSON array
|
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. |
getMetaClass, getProperty, setMetaClass, setProperty
public JsonBuilder()
public JsonBuilder(Object content)
content
- a pre-existing data structurepublic Object getContent()
public Object call(Map m)
Example:
def json = new JsonBuilder()
json name: "Guillaume", age: 33
assert json.toString() == '{"name":"Guillaume","age":33}'
m
- a map of key / value pairspublic Object call(List l)
Example:
def json = new JsonBuilder()
def result = json([1, 2, 3])
assert result instanceof List
assert json.toString() == "[1,2,3]"
l
- a list of valuespublic Object call(Object... args)
Example:
def json = new JsonBuilder()
def result = json 1, 2, 3
assert result instanceof List
assert json.toString() == "[1,2,3]"
args
- an array of valuespublic Object call(Collection coll, Closure c)
Example:
class Author {
String name
}
def authors = [new Author (name: "Guillaume"), new Author (name: "Jochen"), new Author (name: "Paul")]
def json = new 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 collpublic Object call(Closure c)
Example:
def json = new 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 objectpublic Object invokeMethod(String name, Object args)
Example with a classicala builder-style:
def json = new 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 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 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 JsonBuilder()
json.person()
assert json.toString() == '{"person":{}}'
invokeMethod
in interface GroovyObject
invokeMethod
in class GroovyObjectSupport
name
- the single keyargs
- the value associated with the keypublic String toString()
Example:
def json = new JsonBuilder()
json { temperature 37 }
assert json.toString() == '{"temperature":37}'
public String toPrettyString()
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.
public Writer writeTo(Writer out) throws IOException
Writable
interface,
so that you can have the builder serialize itself the JSON payload to a writer.
Example:
def json = new JsonBuilder()
json { temperature 37 }
def out = new StringWriter()
out << json
assert out.toString() == '{"temperature":37}'
writeTo
in interface Writable
out
- a writer on which to serialize the JSON payloadIOException
- if an error occurred while outputting data to the writer