如何在REST Response中为同一个字段解析jsonObject和JsonArray

Question

我使用RestTemplate调用api，假设/ getCompany

通常回复如下： -

"Organization":{
  "name": "My Company",
  "department": {
     "id": "1",
     "employee": [{
       "id": "84",
       "name": "abc"
      },
      {
       "id": "85",
       "name": "xyz"
      }]
 }
}

所以我解析如下： -

ResponseEntity<Organization> company= new RestTemplate().exchange(new URI(companyUrl),HttpMethod.GET,request, Organization.class);
Organization comp= company.getBody();
Department dept= comp.getDepartment();
Employee[] emp = dept.getEmployees()

但有时在响应中我也得到以下json字符串：

"Organization":{
  "name": "My Company",
  "department": {
     "id": "1",
     "employee": {
       "id": "84",
       "name": "abc"
      }     
   }
}

现在我得到以下例外： -

Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of Employee[] out of START_OBJECT token

那么有什么方法可以处理这两种情况吗？

更新： -

根据评论添加以下代码： -

@Bean
public ObjectMapper getObjectMapper() {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.enable(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
    return objectMapper;
}

@Bean
public MappingJackson2HttpMessageConverter mappingJacksonHttpMessageConverter(ObjectMapper objectMapper) {
    MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
    converter.setObjectMapper(objectMapper);
    return converter;
}

但仍然得到同样的例外。

谢谢，

Answer 1

注册的objectMapper必须与ACCEPT_SINGLE_VALUE_AS_ARRAY参数一起使用。

也许最简单的方法是在一个用ObjectMapper注释的类中注册一个正确初始化的MappingJacksonHttpMessageConverter和@Configuration：

@Bean
public ObjectMapper getObjectMapper() {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.enable(ACCEPT_SINGLE_VALUE_AS_ARRAY);
    return objectMapper;
}

@Bean
public MappingJacksonHttpMessageConverter mappingJacksonHttpMessageConverter(ObjectMapper objectMapper) {
    MappingJacksonHttpMessageConverter converter = new MappingJacksonHttpMessageConverter();
    converter.setObjectMapper(objectMapper);
    return converter;
}

另一种方法是将转换器直接设置为restTemplate对象：

public ObjectMapper objectMapper() {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.enable(ACCEPT_SINGLE_VALUE_AS_ARRAY);
    return objectMapper;
}


public MappingJackson2HttpMessageConverter httpConverter(ObjectMapper objectMapper) {
    return new MappingJackson2HttpMessageConverter(objectMapper);
}

public void restTemplate() {
    RestTemplate restTemplate = new RestTemplate();
    restTemplate.setMessageConverters(Arrays.asList(httpConverter(objectMapper())));
    restTemplate.exchange(...);
}

Answer 2

JSON是一个javascript对象表示法。 JSON与javascript的语法相同。在JSON中，数组值必须是string，array，number，object boolean或null类型。