Class FormHttpMessageConverter

java.lang.Object

org.springframework.http.converter.FormHttpMessageConverter

All Implemented Interfaces:

HttpMessageConverter<Object>, SmartHttpMessageConverter<Object>

public class FormHttpMessageConverter
extends Object
implements SmartHttpMessageConverter<Object>

Implementation of HttpMessageConverter to read and write URL encoded forms. For multipart support, see the MultipartHttpMessageConverter.

This converter can read and write the "application/x-www-form-urlencoded" media type as MultiValueMap<String, String>.

Examples

The following snippet shows how to submit an HTML form using the "application/x-www-form-urlencoded" content type.

RestClient restClient = RestClient.create();

MultiValueMap<String, String> form = new LinkedMultiValueMap<>();
form.add("field 1", "value 1");
form.add("field 2", "value 2");
form.add("field 2", "value 3");
form.add("field 3", 4);

ResponseEntity<Void> response = restClient.post()
  .uri("https://example.com/myForm")
  .contentType(MediaType.APPLICATION_FORM_URLENCODED)
  .body(form)
  .retrieve()
  .toBodilessEntity();

Since:

3.0

Author:

Arjen Poutsma, Rossen Stoyanchev, Juergen Hoeller, Sam Brannen, Brian Clozel

See Also:

• MultiValueMap

Field Summary

Fields

Modifier and Type	Field	Description
static final Charset	DEFAULT_CHARSET	The default charset used by the converter.

Constructor Summary

Constructors

Constructor	Description
FormHttpMessageConverter()

Method Summary

Modifier and Type	Method	Description
boolean	canRead(ResolvableType type, @Nullable MediaType mediaType)	Indicates whether the given type can be read by this converter.
boolean	canWrite(ResolvableType targetType, Class<?> valueClass, @Nullable MediaType mediaType)	Indicates whether the given class can be written by this converter.
protected MediaType	getFormContentType(@Nullable MediaType contentType)	Return the content type used to write forms, either the given content type or otherwise application/x-www-form-urlencoded.
List<MediaType>	getSupportedMediaTypes()	Return the list of media types supported by this converter.
Object	read(ResolvableType type, HttpInputMessage inputMessage, @Nullable Map<String,Object> hints)	Read an object of the given type from the given input message, and returns it.
protected String	serializeForm(Map<String,String> formData, Charset charset)
protected String	serializeForm(MultiValueMap<String,String> formData, Charset charset)
void	setCharset(@Nullable Charset charset)	Set the default character set to use for reading and writing form data when the request or response Content-Type header does not explicitly specify it.
void	write(Object data, ResolvableType type, @Nullable MediaType contentType, HttpOutputMessage outputMessage, @Nullable Map<String,Object> hints)	Write a given object to the given output message.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface HttpMessageConverter

canWriteRepeatedly, getSupportedMediaTypes

Methods inherited from interface SmartHttpMessageConverter

canRead, canWrite, read, write

Field Details

DEFAULT_CHARSET

public static final Charset DEFAULT_CHARSET

The default charset used by the converter.

Constructor Details

FormHttpMessageConverter

public FormHttpMessageConverter()

Method Details

getSupportedMediaTypes

public List<MediaType> getSupportedMediaTypes()

Return the list of media types supported by this converter. The list may not apply to every possible target element type and calls to this method should typically be guarded via canWrite(clazz, null. The list may also exclude MIME types supported only for a specific class. Alternatively, use HttpMessageConverter.getSupportedMediaTypes(Class) for a more precise list.

Specified by:

getSupportedMediaTypes in interface HttpMessageConverter<Object>

Returns:

the list of supported media types

setCharset

public void setCharset(@Nullable Charset charset)

Set the default character set to use for reading and writing form data when the request or response Content-Type header does not explicitly specify it.

By default, this is set to "UTF-8".

canRead

public boolean canRead(ResolvableType type,
 @Nullable MediaType mediaType)

Description copied from interface: SmartHttpMessageConverter

Indicates whether the given type can be read by this converter. This method should perform the same checks as HttpMessageConverter.canRead(Class, MediaType) with additional ones related to the generic type.

Specified by:

canRead in interface SmartHttpMessageConverter<Object>

Parameters:

type - the (potentially generic) type to test for readability. The type source may be used for retrieving additional information (the related method signature for example) when relevant.

mediaType - the media type to read, can be null if not specified. Typically, the value of a Content-Type header.

Returns:

true if readable; false otherwise

canWrite

public boolean canWrite(ResolvableType targetType,
 Class<?> valueClass,
 @Nullable MediaType mediaType)

Description copied from interface: SmartHttpMessageConverter

Indicates whether the given class can be written by this converter.

This method should perform the same checks as HttpMessageConverter.canWrite(Class, MediaType) with additional ones related to the generic type.

Specified by:

canWrite in interface SmartHttpMessageConverter<Object>

Parameters:

targetType - the (potentially generic) target type to test for writability (can be ResolvableType.NONE if not specified). The type source may be used for retrieving additional information (the related method signature for example) when relevant.

valueClass - the source object class to test for writability

mediaType - the media type to write (can be null if not specified); typically the value of an Accept header.

Returns:

true if writable; false otherwise

read

public Object read(ResolvableType type,
 HttpInputMessage inputMessage,
 @Nullable Map<String,Object> hints)
            throws IOException,
HttpMessageNotReadableException

Description copied from interface: SmartHttpMessageConverter

Read an object of the given type from the given input message, and returns it.

Specified by:

read in interface SmartHttpMessageConverter<Object>

Parameters:

type - the (potentially generic) type of object to return. This type must have previously been passed to the canRead method of this interface, which must have returned true. The type source may be used for retrieving additional information (the related method signature for example) when relevant.

inputMessage - the HTTP input message to read from

hints - additional information about how to encode

Returns:

the converted object

Throws:

IOException - in case of I/O errors

HttpMessageNotReadableException - in case of conversion errors

write

public void write(Object data,
 ResolvableType type,
 @Nullable MediaType contentType,
 HttpOutputMessage outputMessage,
 @Nullable Map<String,Object> hints)
           throws IOException,
HttpMessageNotWritableException

Description copied from interface: SmartHttpMessageConverter

Write a given object to the given output message.

Specified by:

write in interface SmartHttpMessageConverter<Object>

Parameters:

data - the object to write to the output message. The type of this object must have previously been passed to the canWrite method of this interface, which must have returned true.

type - the (potentially generic) type of object to write. This type must have previously been passed to the canWrite method of this interface, which must have returned true. Can be ResolvableType.NONE if not specified. The type source may be used for retrieving additional information (the related method signature for example) when relevant.

contentType - the content type to use when writing. May be null to indicate that the default content type of the converter must be used. If not null, this media type must have previously been passed to the canWrite method of this interface, which must have returned true.

outputMessage - the message to write to

hints - additional information about how to encode

Throws:

IOException - in case of I/O errors

HttpMessageNotWritableException - in case of conversion errors

getFormContentType

protected MediaType getFormContentType(@Nullable MediaType contentType)

Return the content type used to write forms, either the given content type or otherwise application/x-www-form-urlencoded.

Parameters:

contentType - the content type passed to write(Object, ResolvableType, MediaType, HttpOutputMessage, Map), or null

Returns:

the content type to use

Since:

5.2.2

serializeForm

protected String serializeForm(Map<String,String> formData,
 Charset charset)

serializeForm

protected String serializeForm(MultiValueMap<String,String> formData,
 Charset charset)