org.springframework.http.converter.json

Class GsonHttpMessageConverter

java.lang.Object

org.springframework.http.converter.AbstractHttpMessageConverter<T>

org.springframework.http.converter.AbstractGenericHttpMessageConverter<Object>

org.springframework.http.converter.json.GsonHttpMessageConverter

All Implemented Interfaces:

GenericHttpMessageConverter<Object>, HttpMessageConverter<Object>

public class GsonHttpMessageConverter
extends AbstractGenericHttpMessageConverter<Object>

Implementation of HttpMessageConverter that can read and write JSON using the Google Gson library's Gson class.

This converter can be used to bind to typed beans or untyped HashMaps. By default, it supports application/json and application/*+json with UTF-8 character set.

Tested against Gson 2.8; compatible with Gson 2.0 and higher.

Since:

4.1

Author:

Roy Clarkson

See Also:

setGson(com.google.gson.Gson), AbstractHttpMessageConverter.setSupportedMediaTypes(java.util.List<org.springframework.http.MediaType>)

Field Summary

Fields

Modifier and Type	Field and Description
static Charset	DEFAULT_CHARSET

Fields inherited from class org.springframework.http.converter.AbstractHttpMessageConverter

logger

Constructor Summary

Constructors

Constructor and Description
GsonHttpMessageConverter() Construct a new GsonHttpMessageConverter.

Method Summary

Modifier and Type	Method and Description
com.google.gson.Gson	getGson() Return the configured Gson instance for this converter.
protected com.google.gson.reflect.TypeToken<?>	getTypeToken(Type type) Deprecated. as of Spring Framework 4.3.8, in favor of signature-based resolution
Object	read(Type type, Class<?> contextClass, HttpInputMessage inputMessage) Read an object of the given type form the given input message, and returns it.
protected Object	readInternal(Class<?> clazz, HttpInputMessage inputMessage) Abstract template method that reads the actual object.
void	setGson(com.google.gson.Gson gson) Set the Gson instance to use.
void	setJsonPrefix(String jsonPrefix) Specify a custom prefix to use for JSON output.
void	setPrefixJson(boolean prefixJson) Indicate whether the JSON output by this view should be prefixed with ")]}', ".
protected void	writeInternal(Object o, Type type, HttpOutputMessage outputMessage) Abstract template method that writes the actual body.

Methods inherited from class org.springframework.http.converter.AbstractGenericHttpMessageConverter

canRead, canWrite, supports, write, writeInternal

Methods inherited from class org.springframework.http.converter.AbstractHttpMessageConverter

addDefaultHeaders, canRead, canRead, canWrite, canWrite, getContentLength, getDefaultCharset, getDefaultContentType, getSupportedMediaTypes, read, setDefaultCharset, setSupportedMediaTypes, write

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.http.converter.HttpMessageConverter

canRead, canWrite, getSupportedMediaTypes, read, write

Field Detail

DEFAULT_CHARSET

public static final Charset DEFAULT_CHARSET

Constructor Detail

GsonHttpMessageConverter

public GsonHttpMessageConverter()

Construct a new GsonHttpMessageConverter.

Method Detail

setGson

public void setGson(com.google.gson.Gson gson)

Set the Gson instance to use. If not set, a default Gson instance will be used.

Setting a custom-configured Gson is one way to take further control of the JSON serialization process.

getGson

public com.google.gson.Gson getGson()

Return the configured Gson instance for this converter.

setJsonPrefix

public void setJsonPrefix(String jsonPrefix)

Specify a custom prefix to use for JSON output. Default is none.

See Also:

setPrefixJson(boolean)

setPrefixJson

public void setPrefixJson(boolean prefixJson)

Indicate whether the JSON output by this view should be prefixed with ")]}', ". Default is false.

Prefixing the JSON string in this manner is used to help prevent JSON Hijacking. The prefix renders the string syntactically invalid as a script so that it cannot be hijacked. This prefix should be stripped before parsing the string as JSON.

See Also:

setJsonPrefix(java.lang.String)

read

public Object read(Type type,
                   Class<?> contextClass,
                   HttpInputMessage inputMessage)
            throws IOException,
                   HttpMessageNotReadableException

Description copied from interface: GenericHttpMessageConverter

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

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.

contextClass - a context class for the target type, for example a class in which the target type appears in a method signature (can be null)

inputMessage - the HTTP input message to read from

Returns:

the converted object

Throws:

IOException - in case of I/O errors

HttpMessageNotReadableException - in case of conversion errors

readInternal

protected Object readInternal(Class<?> clazz,
                              HttpInputMessage inputMessage)
                       throws IOException,
                              HttpMessageNotReadableException

Description copied from class: AbstractHttpMessageConverter

Abstract template method that reads the actual object. Invoked from AbstractHttpMessageConverter.read(java.lang.Class<? extends T>, org.springframework.http.HttpInputMessage).

Specified by:

readInternal in class AbstractHttpMessageConverter<Object>

Parameters:

clazz - the type of object to return

inputMessage - the HTTP input message to read from

Returns:

the converted object

Throws:

IOException - in case of I/O errors

HttpMessageNotReadableException - in case of conversion errors

getTypeToken

@Deprecated
protected com.google.gson.reflect.TypeToken<?> getTypeToken(Type type)

Deprecated. as of Spring Framework 4.3.8, in favor of signature-based resolution

Return the Gson TypeToken for the specified type.

The default implementation returns TypeToken.get(type), but this can be overridden in subclasses to allow for custom generic collection handling. For instance:

 protected TypeToken getTypeToken(Type type) {
   if (type instanceof Class && List.class.isAssignableFrom((Class) type)) {
     return new TypeToken>() {};
   }
   else {
     return super.getTypeToken(type);
   }
 }
 

Parameters:

type - the type for which to return the TypeToken

Returns:

the type token

writeInternal

protected void writeInternal(Object o,
                             Type type,
                             HttpOutputMessage outputMessage)
                      throws IOException,
                             HttpMessageNotWritableException

Description copied from class: AbstractGenericHttpMessageConverter

Abstract template method that writes the actual body. Invoked from AbstractGenericHttpMessageConverter.write(T, java.lang.reflect.Type, org.springframework.http.MediaType, org.springframework.http.HttpOutputMessage).

Specified by:

writeInternal in class AbstractGenericHttpMessageConverter<Object>

Parameters:

o - the object to write to the output message

type - the type of object to write (may be null)

outputMessage - the HTTP output message to write to

Throws:

IOException - in case of I/O errors

HttpMessageNotWritableException - in case of conversion errors