找不到类型返回值的转换器：class java.util.LinkedHashMap

Question

我想在mockito单元测试中获得异常的json响应。这是我的应用程序配置文件。

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "com.spring")
public class AppConfig extends WebMvcConfigurerAdapter{

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/resources/**").addResourceLocations("/resources/");
    }

}

这是我现有用户的异常类：

public class ConflictException extends RuntimeException{

    public ConflictException() {

    }

    public ConflictException(String message) {
        super(message);
    }
}

这是我的全局异常控制器类，用 @ControllerAdvice 注释。

@EnableWebMvc
@ControllerAdvice
public class GlobalExceptionHandlerController extends ResponseEntityExceptionHandler{

    public GlobalExceptionHandlerController() {
        super();
    }

    @ExceptionHandler(ConflictException.class)
    public ResponseEntity<Map<String, Object>> handleException(
            Exception exception, HttpServletRequest request) {
        ExceptionAttributes exceptionAttributes = new DefaultExceptionAttributes();
        Map<String, Object> responseBody = exceptionAttributes.getExceptionAttributes(exception, request, HttpStatus.CONFLICT);
        return new ResponseEntity<Map<String,Object>>(responseBody, HttpStatus.CONFLICT);
    }
}

现在，这是我的控制器测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@EnableWebMvc
@ActiveProfiles("Test")
@ContextConfiguration(classes={AppConfig.class})
public class UserControllerTest {

@InjectMocks
    private UserController userController;

    @Mock
     private UserService service;

private MockMvc mockMvc;


    @Before
     public void setup() {
         MockitoAnnotations.initMocks(this);

         final ExceptionHandlerExceptionResolver exceptionHandlerExceptionResolver = new ExceptionHandlerExceptionResolver();

            //here we need to setup a dummy application context that only registers the GlobalControllerExceptionHandler
            final StaticApplicationContext applicationContext = new StaticApplicationContext();
            applicationContext.registerBeanDefinition("advice", new RootBeanDefinition(GlobalExceptionHandlerController.class, null, null));

            //set the application context of the resolver to the dummy application context we just created
            exceptionHandlerExceptionResolver.setApplicationContext(applicationContext);

            //needed in order to force the exception resolver to update it's internal caches
            exceptionHandlerExceptionResolver.afterPropertiesSet();


         mockMvc = MockMvcBuilders.standaloneSetup(userController).setHandlerExceptionResolvers(exceptionHandlerExceptionResolver).build();

     }

@Test
    public void createUserExistsTest() throws Exception {

        when(service.createUser(any(User.class))).thenThrow(new ConflictException("User exists."));

        mockMvc.perform(post("/user")
                .content("{\"username\": \"bimal\", \"password\": \"check\", \"email\": \"test@gmail.com\", \"maxCaloriesPerDay\": \"1000\"}")
                .contentType(MediaType.APPLICATION_JSON))
                .andDo(print())
                .andExpect(status().isConflict());  
    }
}

当我运行测试方法时，出现以下错误：

错误：

org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver - Failed to invoke @ExceptionHandler method: public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> com.spring.app.exception.GlobalExceptionHandlerController.handleException(java.lang.Exception,javax.servlet.http.HttpServletRequest)
java.lang.IllegalArgumentException: No converter found for return value of type: class java.util.LinkedHashMap
    at org.springframework.util.Assert.isTrue(Assert.java:68)

我该如何解决这个错误？抛出异常，但我无法转换和使用它。

Answer 1

正在处理中。此错误是指响应实体类型没有 HttpMessageConverter。将 JacksonHttpMessageConverter 添加到 spring 上下文中。

从 AppConfig 中的 WebMvcConfigurerAdapter 重写此方法：

    @Override
    public void configureMessageConverters(List<HttpMessageConverter> converters) {
        messageConverters.add(new MappingJackson2HttpMessageConverter());
        super.configureMessageConverters(converters);
    }