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YAML

Juneau supports converting arbitrary POJOs to and from YAML using native serializers and parsers implemented without any external dependencies. The YAML serializer converts POJOs directly to YAML block-style output using indentation-based structure. The YAML parser creates POJOs directly from YAML using an indentation-aware state machine.

The following example shows YAML for a typical bean:

Sample Beans​

public class Person {

    // Bean properties
    public String name;
    @MarshalledProp(calendarFormat=CalendarFormat.ISO_INSTANT) public Calendar birthDate;
    public List addresses;

    // Getters/setters omitted
}

public class Address {

    // Bean properties
    public String street, city;
    public StateEnum state;
    public int zip;
    public boolean isCurrent;

    // Getters/setters omitted
}

Sample Code​

Person person = new Person()
    .name("John Smith")
    .birthDate("1946-08-12T00:00:00Z")
    .addresses(
        new Address()
            .street("100 Main Street")
            .city("Anywhereville")
            .state(NY)
            .zip(12345)
            .isCurrent(true)
    );

YAML Output​

name: John Smith
birthDate: '1946-08-12T00:00:00Z'
addresses:
  - street: 100 Main Street
    city: Anywhereville
    state: NY
    zip: 12345
    isCurrent: true

Serialization​

// Use the default serializer to serialize a POJO to YAML
String yaml = YamlSerializer.DEFAULT.write(someObject);

// Use the marshaller for convenience
String yaml = Yaml.of(someObject);

Parsing​

// Use the default parser to parse YAML into a POJO
MyBean bean = YamlParser.DEFAULT.read(yaml, MyBean.class);

// Use the marshaller for convenience
MyBean bean = Yaml.to(yaml, MyBean.class);

Media Types​

  • Produces: application/yaml
  • Accepts: application/yaml, text/yaml

Supported YAML Features​

The parser supports:

  • Block-style mappings and sequences
  • Flow-style mappings ({key: value}) and sequences ([item1, item2])
  • Plain, single-quoted, and double-quoted scalars
  • Literal block scalars (|) and folded block scalars (>)
  • Comments (# ...)
  • Null values (null, ~)
  • Booleans (true, false)
  • Integer and floating-point numbers
  • Document markers (---, ...)
  • Bean type dictionaries via _type property

REST Integration​

// Use BasicYamlConfig for YAML-only REST resources
@Rest
public class MyResource extends RestServlet implements BasicYamlConfig { ... }

// YAML is also included in BasicUniversalConfig
@Rest
public class MyResource extends RestServlet implements BasicUniversalConfig { ... }
See Also