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  5. Java Format

Java Format

MIME type: application/java

ID: java

For the Java data format, DataWeave attempts to map any Java value to a DataWeave value, most often by matching the semantics of DataWeave and Java.

Java Value Mapping

The following table maps Java classes to DataWeave types.

Java Class DataWeave

java.lang.String

String

Enum

String

Class

String

UUID

String

CharSequence

String

Char

String

java.sql.Clob

String

java.io.Reader

String

int

Number

long

Number

double

Number

short

Number

BigInteger

Number

BigDecimal

Number

AtomicInteger

Number

AtomicLong

Number

boolean

Boolean

AtomicBoolean

Boolean

java.util.Collection

Array

java.lang.Iterable

Array

java.util.Iterator

Array

java.util.Map

Object

java.util.Optional

Null or Value

java.util.OptionalInt

Null or Number

java.util.OptionalDouble

Null or Number

java.util.OptionalLong

Null or Number

byte[]

Binary

java.lang.InputStream

Binary

java.nio.ByteBuffer

Binary

byte

Binary

java.lang.File

Binary

java.time.Instant

LocalDateTime

java.time.LocalDateTime

LocalDateTime

java.sql.Timestamp

LocalDateTime

java.sql.Date

LocalDateTime

java.util.Date

LocalDateTime

java.time.ZonedDateTime

DateTime

java.time.LocalTime

LocalTime

java.time.OffsetTime

Time

java.time.LocalDate

Date

java.time.ZoneOffset

TimeZone

java.util.Calendar

DateTime

java.util.XMLGregorianCalendar

DateTime

*[]

Array
If a Java class is not in present in the table, DataWeave treats it as a JavaBean and maps it as an Object type. In this case, DataWeave takes all properties from the Java getters.

Metadata

DataWeave supports the ^class metadata for the Java format.

All Java objects are associated with a class. DataWeave maintains this association by mapping the class to a Metadata property.

payload.^class returns the name of the class of the payload.

The Java writer uses the metadata property to discover the Java class to which the DataWeave value maps. That is, DataWeave uses the metadata property to determine which Java class is to be created from a given DataWeave value. For example, the expression output application/java --- now() as DateTime {class: "java.util.Calendar"} creates a java.util.Calendar.

Enum Custom Type

The Java format supports the Enum custom type. To put a Java enum value into a java.util.Map, the DataWeave Java module defines a custom type called Enum. This custom type enables you to handle a given string as the name of a specified enum type. You must use the class metadata property when specifying the Java class name of the enum, for example: {gender: "Female" as Enum {class: "org.mycompany.Gender"}}

Examples

The following examples show uses of the Java format.

Class Definitions

The Java examples use the following class definitions:

User class:
class User {
    private String name;
    private String lastName;

    public User(){

    }

    public User(String name, String lastName){
        this.name = name;
        this.lastName = lastName;
    }

    public void setName(String name){
        this.name = name;
    }

     public void setLastName(String lastName){
        this.lastName = lastName;
    }

    public String getName(){
        return name;
    }

    public String getLastName(){
        return lastName;
    }
}

The following class extends User.

Customer class:
import java.util.Calendar;
class Customer extends User {
    private Calendar expirationDate;
    private User salesRepr;

    public User(){

    }

    public User(String name, String lastName,Calendar expirationDate){
        super(name,lastName);
        this.expirationDate = expirationDate;
    }

    public void setSalesRepr(User salesRepr){
        this.salesRepr = salesRepr;
    }

    public User getSalesRepr(){
        return this.salesRepr;
    }

    public void  setExpirationDate(Calendar expirationDate){
        this.expirationDate = expirationDate;
    }

    public Calendar getExpirationDate(){
        return this.expirationDate;
    }
}

Example: Access Values of Java Properties

This example shows how to access the values of Java properties.

Input

The User values serves as the input payload to the DataWeave script.

new User("Leandro", "Shokida")

Source

The DataWeave scripts transforms the input value to JSON.

output application/json
---
{
    a: payload.name,
    b: payload.lastName
}

Output

The output is a JSON object that contains key-value pairs. The values are the name and lastName values from the input User object.

{
    "a": "Leandro",
    "b": "Shokida"
}

Example: Create a Customer Object

This example shows how to create an instance of a Customer class. The script outputs the object in the JSON format and MIME type.

Notice that it is not necessary to specify the class of inner properties because their class is inferred from the parent class definition.

output application/json
---
{
    name: "Tomo",
    lastName: "Chibana",
    expirationDate: now(),
    salesRepr: {
        name: "Mariano",
        lastName: "de Achaval",
    }
} as Object {class: "Customer"}

Example: Use a Generic

This example relies on generic support in the class name to create a java.util.ArrayList of User objects.

Note that you do not need to use a generic to specify the class in each instance. The class is taken from the generic in the list.

output application/json
---
[{
    name: "Tomo",
    lastName: "Chibana"
},
{
    name: "Ana",
    lastName: "Felissati"
},
{
    name: "Leandro",
    lastName: "Shokida"
}
] as Array {class: "java.util.ArrayList<User>"}

Configuration Properties

DataWeave supports the following configuration properties for this format.

Reader Properties

There are no reader properties for this format.

Writer Properties

This format accepts properties that provide instructions for writing output data.

Parameter Type Default Description

duplicateKeyAsArray

Boolean

false

Converts the values of duplicate keys in an object to a single array of values to the duplicated key.

Valid values are true or false.

writeAttributes

Boolean

false

Converts attributes of a key into child key-value pairs of that key. The attribute key name starts with @.

Valid values are true or false.

Supported MIME Types

This format supports the following MIME types.

MIME Type

*/java