HTTP状态500-...当我在Spring控制器中使用响应状态注释和返回值时，未知的返回值类型

Question

我编写了以下控制器方法：

    @RequestMapping(value = "/member/createCompany/uploadImage1", method = RequestMethod.GET)
    @ResponseStatus(HttpStatus.OK)
    public Long handle() {
        return 1l;
    }

当我在浏览器中请求此方法时，我看到以下内容：

HTTP Status 500 - Request processing failed; nested exception is java.lang.IllegalArgumentException: Unknown return value type [java.lang.Long]

type Exception report

message Request processing failed; nested exception is java.lang.IllegalArgumentException: Unknown return value type [java.lang.Long]

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalArgumentException: Unknown return value type [java.lang.Long]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:948)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
root cause

java.lang.IllegalArgumentException: Unknown return value type [java.lang.Long]
    org.springframework.util.Assert.notNull(Assert.java:112)
    org.springframework.web.method.support.HandlerMethodReturnValueHandlerComposite.handleReturnValue(HandlerMethodReturnValueHandlerComposite.java:68)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:122)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:827)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(Charac
    .........

我实现服务器端错误还是客户端问题？

更新NJNEX答案。

如果我想在控制器方法中实现以下逻辑，我应该怎么做：

       if(someCondition){
           return 1l;
       }else{
         //I want to return 500 or 400 http code
       }

Answer 1

@restController是控制器的专用版本。它包括@Controller和@响应体注释，因此简化了控制器的实现：

@RestController
@RequestMapping("books-rest")
public class SimpleBookRestController {

@GetMapping("/{id}", produces = "application/json")
public Book getBook(@PathVariable int id) {
    return findBookById(id);
}

private Book findBookById(int id) {
    // ...
}


 }

我考虑过这种情况（未知返回值类型）。我认为你在这门课上应用了@Controller注释。如果要修复它，则需要应用@Controller而不是@RestControllerannotatan。

请参阅此链接，
https://www.baeldung.com/spring-controller-vs-restcontroller

Answer 2

在这种情况下使用@响应体注释。没有它，Spring将返回值解释为视图名称。但它不能很长，这就是为什么你得到错误未知的返回值类型

@ResetseBody注释类似于@刚体。这个注释可以放在一个方法上，并指示返回类型应该直接写入HTTP响应主体（而不是放在模型中，或者解释为视图名称）。

Spring参考响应

如果你想返回错误代码从响应体使用：

return new ResponseEntity<String>(HttpStatus.BAD_REQUEST);

另请参见如何在@ResponseBody中响应HTTP错误