我正在用Spring创建一个REST服务，并收到一个异常，告诉我以下信息。
预期的多部分HttpServlet请求：是否配置了MultipartResolver？
当我将方法= RequestMethod.PUT更改为方法= RequestMethod.POST时，它可以正常工作。
为什么我在PUT上得到这个异常，而在POST上没有？

@Configuration
@ComponentScan("io.myservice")
@EnableAutoConfiguration
@EnableCaching
@EnableAsync(mode = ASPECTJ)
public class Application implements AsyncConfigurer {

static org.slf4j.Logger LOG = LoggerFactory.getLogger(Application.class);

public static final String MAX_FILE_SIZE = "2MB";
public static final String MAX_REQUEST_SIZE = "2MB";
public static final String FILE_SIZE_THRESHOLD = "2MB";

@Value("${app.dir.incoming}")
public String createdDir;

@Bean
public LocalValidatorFactoryBean localValidatorFactoryBean() {
    return new LocalValidatorFactoryBean();
}

@Bean
MultipartConfigElement multipartConfigElement() {
    String absTempPath = new File(createdDir).getAbsolutePath();
    MultipartConfigFactory  factory = new MultipartConfigFactory();
    factory.setMaxFileSize(MAX_FILE_SIZE);
    factory.setMaxRequestSize(MAX_REQUEST_SIZE);
    factory.setFileSizeThreshold(FILE_SIZE_THRESHOLD);
    factory.setLocation(absTempPath);
    return factory.createMultipartConfig();
}

@Bean
public StandardServletMultipartResolver multipartResolver() {
    return new StandardServletMultipartResolver();
}

@Override
@Bean
public ThreadPoolTaskExecutor getAsyncExecutor() {
    ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
    executor.setCorePoolSize(2);
    executor.setMaxPoolSize(2);
    executor.setQueueCapacity(5);
    executor.initialize();
    return executor;
}

@Bean
public SimpleCacheManager cacheManager(){
    SimpleCacheManager cacheManager = new SimpleCacheManager();
    List<Cache> caches = new ArrayList<Cache>();
    caches.add(cacheBean());
    cacheManager.setCaches(caches );
    return cacheManager;
}

@Bean
public Cache cacheBean(){
    Cache  cache = new ConcurrentMapCache("default");
    return cache;
}

public static void main(String[] args) throws IOException {
    SysOutOverSLF4J.sendSystemOutAndErrToSLF4J();
    run(Application.class, args);
}
}

@RequestMapping(value="/converter", method=RequestMethod.PUT)
@ResponseBody
public String convert(MultipartFile file) {
    LOG.info("received new file to convert")
}

Caused by: java.lang.IllegalArgumentException: Expected MultipartHttpServletRequest: is a MultipartResolver configured?
at org.springframework.util.Assert.notNull(Assert.java:112)
at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.resolveName(RequestParamMethodArgumentResolver.java:171)
at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:89)
at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:79)
at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:157)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:124)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
... 37 common frames omitted