public ServletInputStream getInputStream() throws IOException; 

public ServletOutputStream getOutputStream() throws IOException;

package org.springframework.http;

import java.io.IOException;
import java.io.InputStream;

public interface HttpInputMessage extends HttpMessage {

 InputStream getBody() throws IOException;

}

package org.springframework.http;

import java.io.IOException;
import java.io.OutputStream;

public interface HttpOutputMessage extends HttpMessage {

 OutputStream getBody() throws IOException;

}

package org.springframework.http.converter;

import java.io.IOException;
import java.util.List;

import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;

public interface HttpMessageConverter<T> {

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

 boolean canWrite(Class<?> clazz, MediaType mediaType);

 List<MediaType> getSupportedMediaTypes();

 T read(Class<? extends T> clazz, HttpInputMessage inputMessage)
 throws IOException, HttpMessageNotReadableException;

 void write(T t, MediaType contentType, HttpOutputMessage outputMessage)
 throws IOException, HttpMessageNotWritableException;

}

@RequestMapping(value="/string", method=RequestMethod.POST)
public @ResponseBody String readString(@RequestBody String string) {
 return "Read string '" + string + "'";
}

package org.springframework.web.method.support;

import org.springframework.core.MethodParameter;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.support.WebDataBinderFactory;
import org.springframework.web.context.request.NativeWebRequest;

public interface HandlerMethodArgumentResolver {

 boolean supportsParameter(MethodParameter parameter);

 Object resolveArgument(MethodParameter parameter,
   ModelAndViewContainer mavContainer,
   NativeWebRequest webRequest,
   WebDataBinderFactory binderFactory) throws Exception;

}

package org.springframework.web.method.support;

import org.springframework.core.MethodParameter;
import org.springframework.web.context.request.NativeWebRequest;

public interface HandlerMethodReturnValueHandler {

 boolean supportsReturnType(MethodParameter returnType);

 void handleReturnValue(Object returnValue,
   MethodParameter returnType,
   ModelAndViewContainer mavContainer,
   NativeWebRequest webRequest) throws Exception;

}

public boolean supportsParameter(MethodParameter parameter) {
 return parameter.hasParameterAnnotation(RequestBody.class);
}

public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
 NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

 Object argument = readWithMessageConverters(webRequest, parameter, parameter.getGenericParameterType());

 String name = Conventions.getVariableNameForParameter(parameter);
 WebDataBinder binder = binderFactory.createBinder(webRequest, argument, name);

 if (argument != null) {
 validate(binder, parameter);
 }

 mavContainer.addAttribute(BindingResult.MODEL_KEY_PREFIX + name, binder.getBindingResult());

 return argument;
}

public boolean supportsReturnType(MethodParameter returnType) {
 return returnType.getMethodAnnotation(ResponseBody.class) != null;
}

 public void handleReturnValue(Object returnValue, MethodParameter returnType,
 ModelAndViewContainer mavContainer, NativeWebRequest webRequest)
 throws IOException, HttpMediaTypeNotAcceptableException {

 mavContainer.setRequestHandled(true);
 if (returnValue != null) {
 writeWithMessageConverters(returnValue, returnType, webRequest);
 }
}