Java Reference
In-Depth Information
To generate JSON data using the JSON-P streaming API, first we need to invoke
a call to the static
Json.createGenerator()
method. This method returns an
instance of a class implementing
javax.json.stream.JsonGenerator
. There are
two overloaded versions of the
Json.createGenerator()
method, one takes an
instance of
java.io.OutputStream
(or one of its subclasses) as a parameter and
the other one takes an instance of
java.io.Writer
(or one of its subclasses) as a
parameter. In our example we chose the second version, passing an instance of
java.io.StringWriter
to
Json.createGenerator()
.
Once we obtain an instance of
JsonGenerator
, we need to invoke the
writeStartObject()
method on it. This method writes the start object character
of JSON (the opening curly brace
{
) to the
OutputStream
or
Writer
we passed to
Json.createGenerator()
. The
writeStartObject()
method returns another
instance of
JsonGenerator
, allowing us to immediately invoke the
write()
method on the resulting
JsonGenerator
.
The
write()
method of
JsonGenerator
adds a JSON property to our JSON data. Its
first parameter is a string containing the property value, and its second parameter
is the corresponding value. There are several overloaded versions of the
write()
method, one for each corresponding supported JSON value type (either
String
or a
numeric type such as
BigInteger
or
double
). In our example, we are only adding
properties of the type
String
and
Integer
, therefore we used the corresponding
versions of the
write()
methods. The following table lists all of the existing versions
of the
write()
method:
write() method
Description
write(String name,
BigDecimal value)
Adds a numeric property of type
BigDecimal
to our
JSON data
write(String name,
BigInteger value)
Adds a numeric property of type
BigInteger
to our
JSON data
write(String name,
JsonValue value)
Adds a property of type
JsonValue
or one of its
subinterfaces (
JsonArray
,
JsonNumber
,
JsonObject
,
JsonString
or
JsonStructure
) to our JSON data
write(String name,
String value)
Adds a property of type
String
to our JSON data
write(String name,
boolean value)
Adds a
boolean
property to our JSON data
write(String name,
double value)
Adds a numeric property of type
double
to our JSON data
write(String name,
int value)
Writes a numeric property of type
int
to our JSON data
write(String name,
long value)
Writes a numeric property of type
long
to our JSON data
