## org.springframework.http.converter.json
Class MappingJackson2HttpMessageConverter

    java.lang.Object
      org.springframework.http.converter.AbstractHttpMessageConverter<Object>
          org.springframework.http.converter.json.MappingJackson2HttpMessageConverter

All Implemented Interfaces:
  HttpMessageConverter<Object>

    public class MappingJackson2HttpMessageConverter

extends AbstractHttpMessageConverter<Object>

Implementation of `HttpMessageConverter` that can read and write JSON using Jackson 2's `ObjectMapper`.

This converter can be used to bind to typed beans, or untyped `HashMap` instances.

By default, this converter supports `application/json`. This can be overridden by setting the `supportedMediaTypes` property.

Since:
  3.1.2
Author:
  Arjen Poutsma, Keith Donald
See Also:
  `MappingJackson2JsonView`

Field Summary
`static Charset` `DEFAULT_CHARSET`

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

Constructor Summary
`MappingJackson2HttpMessageConverter()` Construct a new `BindingJacksonHttpMessageConverter`.

Method Summary
`boolean` `canRead(Class<?> clazz, MediaType mediaType)` This implementation checks if the given class is supported, and if the supported media types include the given media type.
`boolean` `canWrite(Class<?> clazz, MediaType mediaType)` This implementation checks if the given class is supported, and if the supported media types include the given media type.
`protected com.fasterxml.jackson.databind.JavaType` `getJavaType(Class<?> clazz)` Return the Jackson `JavaType` for the specified class.
`protected com.fasterxml.jackson.core.JsonEncoding` `getJsonEncoding(MediaType contentType)` Determine the JSON encoding to use for the given content type.
`com.fasterxml.jackson.databind.ObjectMapper` `getObjectMapper()` Return the underlying `ObjectMapper` for this view.
`protected Object` `readInternal(Class<?> clazz, HttpInputMessage inputMessage)` Abstract template method that reads the actualy object.
`void` `setObjectMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper)` Set the `ObjectMapper` for this view.
`void` `setPrefixJson(boolean prefixJson)` Indicate whether the JSON output by this view should be prefixed with "{} &&".
`protected boolean` `supports(Class<?> clazz)` Indicates whether the given class is supported by this converter.
`protected void` `writeInternal(Object object, HttpOutputMessage outputMessage)` Abstract template method that writes the actual body.

Methods inherited from class org.springframework.http.converter.AbstractHttpMessageConverter
`canRead, canWrite, getContentLength, getDefaultContentType, getSupportedMediaTypes, read, setSupportedMediaTypes, write`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### DEFAULT_CHARSET

    public static final Charset DEFAULT_CHARSET

Constructor Detail

### MappingJackson2HttpMessageConverter

    public MappingJackson2HttpMessageConverter()

  Construct a new `BindingJacksonHttpMessageConverter`.

Method Detail

### setObjectMapper

    public void setObjectMapper(com.fasterxml.jackson.databind.ObjectMapper objectMapper)

  Set the `ObjectMapper` for this view. If not set, a default `ObjectMapper` is used.

  Setting a custom-configured `ObjectMapper` is one way to take further control of the JSON serialization process. For example, an extended `SerializerFactory` can be configured that provides custom serializers for specific types. The other option for refining the serialization process is to use Jackson's provided annotations on the types to be serialized, in which case a custom-configured ObjectMapper is unnecessary.

### getObjectMapper

    public com.fasterxml.jackson.databind.ObjectMapper getObjectMapper()

  Return the underlying `ObjectMapper` for this view.

### 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 does not affect the evaluation of JSON, but if JSON validation is performed on the string, the prefix would need to be ignored.

### canRead

    public boolean canRead(Class<?> clazz,
                           MediaType mediaType)

  Description copied from class: `AbstractHttpMessageConverter`
  This implementation checks if the given class is supported, and if the supported media types include the given media type.

  Specified by:
    `canRead` in interface `HttpMessageConverter<Object>`
  Overrides:
    `canRead` in class `AbstractHttpMessageConverter<Object>`
  Parameters:
    `clazz` - the class to test for readability
    `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(Class<?> clazz,
                            MediaType mediaType)

  Description copied from class: `AbstractHttpMessageConverter`
  This implementation checks if the given class is supported, and if the supported media types include the given media type.

  Specified by:
    `canWrite` in interface `HttpMessageConverter<Object>`
  Overrides:
    `canWrite` in class `AbstractHttpMessageConverter<Object>`
  Parameters:
    `clazz` - the 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

### supports

    protected boolean supports(Class<?> clazz)

  Description copied from class: `AbstractHttpMessageConverter`
  Indicates whether the given class is supported by this converter.

  Specified by:
    `supports` in class `AbstractHttpMessageConverter<Object>`
  Parameters:
    `clazz` - the class to test for support
  Returns:
    `true` if supported; `false` otherwise

### readInternal

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

  Description copied from class: `AbstractHttpMessageConverter`
  Abstract template method that reads the actualy 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

### writeInternal

    protected void writeInternal(Object object,
                                 HttpOutputMessage outputMessage)
                          throws IOException,
                                 HttpMessageNotWritableException

  Description copied from class: `AbstractHttpMessageConverter`
  Abstract template method that writes the actual body. Invoked from `AbstractHttpMessageConverter.write(T, org.springframework.http.MediaType, org.springframework.http.HttpOutputMessage)`.

  Specified by:
    `writeInternal` in class `AbstractHttpMessageConverter<Object>`
  Parameters:
    `object` - the object to write to the output message
    `outputMessage` - the message to write to
  Throws:
    `IOException` - in case of I/O errors
    `HttpMessageNotWritableException` - in case of conversion errors

### getJavaType

    protected com.fasterxml.jackson.databind.JavaType getJavaType(Class<?> clazz)

  Return the Jackson `JavaType` for the specified class.

  The default implementation returns `ObjectMapper.constructType(java.lang.reflect.Type)`, but this can be overridden in subclasses, to allow for custom generic collection handling. For instance:

       protected JavaType getJavaType(Class<?> clazz) {
         if (List.class.isAssignableFrom(clazz)) {
           return objectMapper.getTypeFactory().constructCollectionType(ArrayList.class, MyBean.class);
         } else {
           return super.getJavaType(clazz);
         }
       }

  Parameters:
    `clazz` - the class to return the java type for
  Returns:
    the java type

### getJsonEncoding

    protected com.fasterxml.jackson.core.JsonEncoding getJsonEncoding(MediaType contentType)

  Determine the JSON encoding to use for the given content type.

  Parameters:
    `contentType` - the media type as requested by the caller
  Returns:
    the JSON encoding to use (never `null`)