<span style="font-family:Microsoft YaHei;">/**
 * Strategy interface that specifies a converter that can convert from and to HTTP requests and responses.
 *
 * @author Arjen Poutsma
 * @author Juergen Hoeller
 * @since 3.0
 */
public interface HttpMessageConverter<T> {

    /**
     * Indicates whether the given class can be read by this converter.
     * @param clazz the class to test for readability
     * @param mediaType the media type to read, can be {@code null} if not specified.
     * Typically the value of a {@code Content-Type} header.
     * @return {@code true} if readable; {@code false} otherwise
     */
    boolean canRead(Class<?> clazz, MediaType mediaType);

    /**
     * Indicates whether the given class can be written by this converter.
     * @param clazz the class to test for writability
     * @param mediaType the media type to write, can be {@code null} if not specified.
     * Typically the value of an {@code Accept} header.
     * @return {@code true} if writable; {@code false} otherwise
     */
    boolean canWrite(Class<?> clazz, MediaType mediaType);

    /**
     * Return the list of {@link MediaType} objects supported by this converter.
     * @return the list of supported media types
     */
    List<MediaType> getSupportedMediaTypes();

    /**
     * Read an object of the given type form the given input message, and returns it.
     * @param clazz the type of object to return. This type must have previously been passed to the
     * {@link #canRead canRead} method of this interface, which must have returned {@code true}.
     * @param inputMessage the HTTP input message to read from
     * @return the converted object
     * @throws IOException in case of I/O errors
     * @throws HttpMessageNotReadableException in case of conversion errors
     */
    T read(Class<? extends T> clazz, HttpInputMessage inputMessage)
            throws IOException, HttpMessageNotReadableException;

    /**
     * Write an given object to the given output message.
     * @param t the object to write to the output message. The type of this object must have previously been
     * passed to the {@link #canWrite canWrite} method of this interface, which must have returned {@code true}.
     * @param contentType the content type to use when writing. May be {@code null} to indicate that the
     * default content type of the converter must be used. If not {@code null}, this media type must have
     * previously been passed to the {@link #canWrite canWrite} method of this interface, which must have
     * returned {@code true}.
     * @param outputMessage the message to write to
     * @throws IOException in case of I/O errors
     * @throws HttpMessageNotWritableException in case of conversion errors
     */
    void write(T t, MediaType contentType, HttpOutputMessage outputMessage)
            throws IOException, HttpMessageNotWritableException;

}
</span>

    ByteArrayHttpMessageConverter converts byte arrays.

    StringHttpMessageConverter converts strings.

    ResourceHttpMessageConverter converts to/from org.springframework.core.io.Resource for all media types.

    SourceHttpMessageConverter converts to/from a javax.xml.transform.Source.

    FormHttpMessageConverter converts form data to/from a MultiValueMap<String, String>.

    Jaxb2RootElementHttpMessageConverter converts Java objects to/from XML — added if JAXB2 is present on the classpath.

    MappingJacksonHttpMessageConverter converts to/from JSON — added if Jackson is present on the classpath.

    AtomFeedHttpMessageConverter converts Atom feeds — added if Rome is present on the classpath.

    RssChannelHttpMessageConverter converts RSS feeds — added if Rome is present on the classpath.

private Object readWithMessageConverters(MethodParameter methodParam, HttpInputMessage inputMessage, Class paramType)
            throws Exception {

        MediaType contentType = inputMessage.getHeaders().getContentType();
        if (contentType == null) {
            StringBuilder builder = new StringBuilder(ClassUtils.getShortName(methodParam.getParameterType()));
            String paramName = methodParam.getParameterName();
            if (paramName != null) {
                builder.append(' ');
                builder.append(paramName);
            }
            throw new HttpMediaTypeNotSupportedException(
                    "Cannot extract parameter (" + builder.toString() + "): no Content-Type found");
        }

        List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
        if (this.messageConverters != null) {
            for (HttpMessageConverter<?> messageConverter : this.messageConverters) {
                allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
                if (messageConverter.canRead(paramType, contentType)) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Reading [" + paramType.getName() + "] as "" + contentType
                                +"" using [" + messageConverter + "]");
                    }
                    return messageConverter.read(paramType, inputMessage);
                }
            }
        }
        throw new HttpMediaTypeNotSupportedException(contentType, allSupportedMediaTypes);
    }

private void writeWithMessageConverters(Object returnValue,
                HttpInputMessage inputMessage, HttpOutputMessage outputMessage)
                throws IOException, HttpMediaTypeNotAcceptableException {
            List<MediaType> acceptedMediaTypes = inputMessage.getHeaders().getAccept();
            if (acceptedMediaTypes.isEmpty()) {
                acceptedMediaTypes = Collections.singletonList(MediaType.ALL);
            }
            MediaType.sortByQualityValue(acceptedMediaTypes);
            Class<?> returnValueType = returnValue.getClass();
            List<MediaType> allSupportedMediaTypes = new ArrayList<MediaType>();
            if (getMessageConverters() != null) {
                for (MediaType acceptedMediaType : acceptedMediaTypes) {
                    for (HttpMessageConverter messageConverter : getMessageConverters()) {
                        if (messageConverter.canWrite(returnValueType, acceptedMediaType)) {
                            messageConverter.write(returnValue, acceptedMediaType, outputMessage);
                            if (logger.isDebugEnabled()) {
                                MediaType contentType = outputMessage.getHeaders().getContentType();
                                if (contentType == null) {
                                    contentType = acceptedMediaType;
                                }
                                logger.debug("Written [" + returnValue + "] as "" + contentType +
                                        "" using [" + messageConverter + "]");
                            }
                            this.responseArgumentUsed = true;
                            return;
                        }
                    }
                }
                for (HttpMessageConverter messageConverter : messageConverters) {
                    allSupportedMediaTypes.addAll(messageConverter.getSupportedMediaTypes());
                }
            }
            throw new HttpMediaTypeNotAcceptableException(allSupportedMediaTypes);
        }

@Controller
@RequestMapping("/appointments")
public class AppointmentsController {

    private AppointmentBook appointmentBook;
    
    @Autowired
    public AppointmentsController(AppointmentBook appointmentBook) {
        this.appointmentBook = appointmentBook;
    }

    @RequestMapping(method = RequestMethod.GET)
    public Map<String, Appointment> get() {
        return appointmentBook.getAppointmentsForToday();
    }

    @RequestMapping(value="/{day}", method = RequestMethod.GET)
    public Map<String, Appointment> getForDay(@PathVariable @DateTimeFormat(iso=ISO.DATE) Date day, Model model) {
        return appointmentBook.getAppointmentsForDay(day);
    }

    @RequestMapping(value="/new", method = RequestMethod.GET)
    public AppointmentForm getNewForm() {
        return new AppointmentForm();
    }

    @RequestMapping(method = RequestMethod.POST)
    public String add(@Valid AppointmentForm appointment, BindingResult result) {
        if (result.hasErrors()) {
            return "appointments/new";
        }
        appointmentBook.addAppointment(appointment);
        return "redirect:/appointments";
    }
}

@RequestMapping(value="/owners/{ownerId}", method=RequestMethod.GET)
public String findOwner(@PathVariable String ownerId, Model model) {
  Owner owner = ownerService.findOwner(ownerId);  
  model.addAttribute("owner", owner);  
  return "displayOwner"; 
}

@RequestMapping("/spring-web/{symbolicName:[a-z-]+}-{version:d.d.d}.{extension:.[a-z]}")
  public void handle(@PathVariable String version, @PathVariable String extension) {    
    // ...
  }
}

@Controller
@RequestMapping(value = "/pets", method = RequestMethod.POST, consumes="application/json")
public void addPet(@RequestBody Pet pet, Model model) {    
    // implementation omitted
}

@Controller
@RequestMapping(value = "/pets/{petId}", method = RequestMethod.GET, produces="application/json")
@ResponseBody
public Pet getPet(@PathVariable String petId, Model model) {    
    // implementation omitted
}

@Controller
@RequestMapping("/owners/{ownerId}")
public class RelativePathUriTemplateController {

  @RequestMapping(value = "/pets/{petId}", method = RequestMethod.GET, params="myParam=myValue")
  public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {    
    // implementation omitted
  }
}

@Controller
@RequestMapping("/owners/{ownerId}")
public class RelativePathUriTemplateController {

@RequestMapping(value = "/pets", method = RequestMethod.GET, headers="Referer=http://www.ifeng.com/")
  public void findPet(@PathVariable String ownerId, @PathVariable String petId, Model model) {    
    // implementation omitted
  }
}