Package javax.json.stream
Interface JsonGenerator
- All Superinterfaces:
AutoCloseable
,Closeable
,Flushable
Writes JSON data to an output source in a streaming way. The class
Json
contains methods to create generators for character
or output streams (Writer
and OutputStream
).
The following example shows how to create a JSON generator:
JsonGenerator generator = Json.createGenerator(...);
The class JsonGeneratorFactory
also contains methods to create
JsonGenerator
instances. JsonGeneratorFactory
should be used
when creating multiple generator instances, as in the following example:
JsonGeneratorFactory factory = Json.createGeneratorFactory();
JsonGenerator generator1 = factory.createGenerator(...);
JsonGenerator generator2 = factory.createGenerator(...);
JSON objects can be created using JsonGenerator
by calling the
writeStartObject()
method and then adding name/value pairs with the
write
method.
The following example shows how to generate an empty JSON object:
JsonGenerator generator = ...;
generator.writeStartObject().writeEnd().close();
JSON arrays can be created using JsonGenerator
by calling the
writeStartArray()
method and then adding values with the
write
method.
The following example shows how to generate an empty JSON array:
JsonGenerator generator = ...;
generator.writeStartArray().writeEnd().close();
Other JSON values (that are not JSON objects or arrays) can be created
by calling the appropiate write
methods.
The following example shows how to generate a JSON string:
JsonGenerator generator = ...;
generator.write("message").close();
JsonGenerator
methods can be chained as in the following example:
generator
.writeStartObject()
.write("firstName", "John")
.write("lastName", "Smith")
.write("age", 25)
.writeStartObject("address")
.write("streetAddress", "21 2nd Street")
.write("city", "New York")
.write("state", "NY")
.write("postalCode", "10021")
.writeEnd()
.writeStartArray("phoneNumber")
.writeStartObject()
.write("type", "home")
.write("number", "212 555-1234")
.writeEnd()
.writeStartObject()
.write("type", "fax")
.write("number", "646 555-4567")
.writeEnd()
.writeEnd()
.writeEnd();
generator.close();
The example code above generates the following JSON (or equivalent):
{
"firstName": "John", "lastName": "Smith", "age": 25,
"address" : {
"streetAddress": "21 2nd Street",
"city": "New York",
"state": "NY",
"postalCode": "10021"
},
"phoneNumber": [
{"type": "home", "number": "212 555-1234"},
{"type": "fax", "number": "646 555-4567"}
]
}
The generated JSON text must strictly conform to the grammar defined in
RFC 7159.- See Also:
-
Field Summary
Modifier and TypeFieldDescriptionstatic final String
Configuration property to generate JSON prettily. -
Method Summary
Modifier and TypeMethodDescriptionvoid
close()
Closes this generator and frees any resources associated with it.void
flush()
Flushes the underlying output source.write
(boolean value) Writes a JSON true or false value within the current array, field or root context.write
(double value) Writes the specified value as a JSON number value within the current array, field or root context.write
(int value) Writes the specified value as a JSON number value within the current array, field or root context.write
(long value) Writes the specified value as a JSON number value within the current array, field or root context.Writes the specified value as a JSON string value within the current array, field or root context.Writes a JSON name/boolean value pair in the current object context.Writes a JSON name/number value pair in the current object context.Writes a JSON name/number value pair in the current object context.Writes a JSON name/number value pair in the current object context.Writes a JSON name/string value pair in the current object context.write
(String name, BigDecimal value) Writes a JSON name/number value pair in the current object context.write
(String name, BigInteger value) Writes a JSON name/number value pair in the current object context.Writes a JSON name/value pair in the current object context.write
(BigDecimal value) Writes the specified value as a JSON number value within the current array, field or root context.write
(BigInteger value) Writes the specified value as a JSON number value within the current array, field or root context.Writes the specified value as a JSON value within the current array, field or root context.writeEnd()
Writes the end of the current context.Writes the JSON name with a colon.Writes a JSON null value within the current array, field or root context.Writes a JSON name/null value pair in an current object context.Writes the JSON start array character.writeStartArray
(String name) Writes the JSON name/start array character pair with in the current object context.Writes the JSON start object character.writeStartObject
(String name) Writes the JSON name/start object character pair in the current object context.
-
Field Details
-
PRETTY_PRINTING
Configuration property to generate JSON prettily. All providers must support this property. The value of the property could be be anything.- See Also:
-
-
Method Details
-
writeStartObject
JsonGenerator writeStartObject()Writes the JSON start object character. It starts a new child object context within which JSON name/value pairs can be written to the object. This method is valid only in an array context, field context or in no context (when a context is not yet started). This method can only be called once in no context.- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is called within an object context or if it is called more than once in no context.
-
writeStartObject
Writes the JSON name/start object character pair in the current object context. It starts a new child object context within which JSON name/value pairs can be written to the object.- Parameters:
name
- a name within the JSON name/object pair to be written- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context
-
writeKey
Writes the JSON name with a colon. It starts a field context, in which valid options are writing a value, starting an object or an array. Writing value closes field context, if object or array is started after field name, field context will be closed after object/array close.- Parameters:
name
- name of json field- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context- Since:
- 1.1
-
writeStartArray
JsonGenerator writeStartArray()Writes the JSON start array character. It starts a new child array context within which JSON values can be written to the array. This method is valid only in an array context, field context or in no context (when a context is not yet started). This method can only be called once in no context.- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is called within an object context or if called more than once in no context
-
writeStartArray
Writes the JSON name/start array character pair with in the current object context. It starts a new child array context within which JSON values can be written to the array.- Parameters:
name
- a name within the JSON name/array pair to be written- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context
-
write
Writes a JSON name/value pair in the current object context.- Parameters:
name
- a name in the JSON name/value pair to be written in current JSON objectvalue
- a value in the JSON name/value pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context
-
write
Writes a JSON name/string value pair in the current object context. The specified value is written as JSON string value.- Parameters:
name
- a name in the JSON name/string pair to be written in current JSON objectvalue
- a value in the JSON name/string pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context
-
write
Writes a JSON name/number value pair in the current object context. The specified value is written as a JSON number value. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
name
- a name in the JSON name/number pair to be written in current JSON objectvalue
- a value in the JSON name/number pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context.
-
write
Writes a JSON name/number value pair in the current object context. The specified value is written as a JSON number value. The specified value'stoString()
is used as the text value for writing.- Parameters:
name
- a name in the JSON name/number pair to be written in current JSON objectvalue
- a value in the JSON name/number pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context.
-
write
Writes a JSON name/number value pair in the current object context. The specified value is written as a JSON number value. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
name
- a name in the JSON name/number pair to be written in current JSON objectvalue
- a value in the JSON name/number pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context.
-
write
Writes a JSON name/number value pair in the current object context. The specified value is written as a JSON number value. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
name
- a name in the JSON name/number pair to be written in current JSON objectvalue
- a value in the JSON name/number pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context.
-
write
Writes a JSON name/number value pair in the current object context. The specified value is written as a JSON number value. The stringBigDecimal.valueOf(double).toString()
is used as the text value for writing.- Parameters:
name
- a name in the JSON name/number pair to be written in current JSON objectvalue
- a value in the JSON name/number pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)NumberFormatException
- if the value is Not-a-Number (NaN) or infinity.JsonGenerationException
- if this method is not called within an object context
-
write
Writes a JSON name/boolean value pair in the current object context. If value is true, it writes the JSONtrue
value, otherwise it writes the JSONfalse
value.- Parameters:
name
- a name in the JSON name/boolean pair to be written in current JSON objectvalue
- a value in the JSON name/boolean pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context.
-
writeNull
Writes a JSON name/null value pair in an current object context.- Parameters:
name
- a name in the JSON name/null pair to be written in current JSON object- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an object context
-
writeEnd
JsonGenerator writeEnd()Writes the end of the current context. If the current context is an array context, this method writes the end-of-array character (']'). If the current context is an object context, this method writes the end-of-object character ('}'). After writing the end of the current context, the parent context becomes the new current context. If parent context is field context, it is closed.- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is called in no context.
-
write
Writes the specified value as a JSON value within the current array, field or root context.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
write
Writes the specified value as a JSON string value within the current array, field or root context.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
write
Writes the specified value as a JSON number value within the current array, field or root context. The specified value'stoString()
is used as the the text value for writing.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.- See Also:
-
write
Writes the specified value as a JSON number value within the current array, field or root context. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator.
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.- See Also:
-
write
Writes the specified value as a JSON number value within the current array, field or root context. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
write
Writes the specified value as a JSON number value within the current array, field or root context. The stringnew BigDecimal(value).toString()
is used as the text value for writing.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
write
Writes the specified value as a JSON number value within the current array, field or root context. The stringBigDecimal.valueOf(value).toString()
is used as the text value for writing.- Parameters:
value
- a value to be written in current JSON array- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.NumberFormatException
- if the value is Not-a-Number (NaN) or infinity.
-
write
Writes a JSON true or false value within the current array, field or root context. If value is true, this method writes the JSONtrue
value, otherwise it writes the JSONfalse
value.- Parameters:
value
- aboolean
value- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
writeNull
JsonGenerator writeNull()Writes a JSON null value within the current array, field or root context.- Returns:
- this generator
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if this method is not called within an array or root context.
-
close
void close()Closes this generator and frees any resources associated with it. This method closes the underlying output source.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)JsonGenerationException
- if an incomplete JSON is generated
-
flush
void flush()Flushes the underlying output source. If the generator has saved any characters in a buffer, writes them immediately to the underlying output source before flushing it.- Specified by:
flush
in interfaceFlushable
- Throws:
JsonException
- if an i/o error occurs (IOException would be cause of JsonException)
-