Spring 中的 Jackson Object Mapper 不工作

Question

我有 Spring MVC 应用程序，它从 Java 脚本前端接收 JSON POSTed。使用 Jackson 2，自定义对象映射器仅将 ACCEPT_SINGLE_VALUE_AS_ARRAY 设置为 true。下面是我的代码片段。

启用 MVC Java 配置：

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(0, jackson2Converter());
    }

    @Primary
    @Bean
    public MappingJackson2HttpMessageConverter jackson2Converter() {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        converter.setObjectMapper(objectMapper());
        return converter;
    }

    @Primary
    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
        return objectMapper;
    }
}

Controller.java:

@RequestMapping(value = "home", method = RequestMethod.POST, consumes = "application/json")
@ResponseBody
public String submitForm(@RequestBody final Shipment shipment) { 
...
}

POJO:

  class Shipment implements Serializable { 

    private String dstState;
    private List<String> dstCities;
    // getters, setters and default constructor
    }

Ajax POST 来电：

$.ajax({ url: ".../home", type: "POST", data: JSON.stringify(("#shipForm").serializeArray()), contentType: "application/json", dataType: 'json', ....

JSON 发布对象：mydata: {"dstState":"NV" ,"dstCities":"Las Vegas"}

收到POST后，出现错误：

Could not read JSON: Can not deserialize instance of java.util.ArrayList out of VALUE_STRING token
 at [Source: java.io.PushbackInputStream@44733b90; line: 1, column: 90] (through reference chain: com.*.Shipment["dstCities"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of VALUE_STRING token

请指出我在这里遗漏的任何内容

Answer 1

您输入的json数据格式不正确

Shipment Json表示：

Shipment 是 Json 对象
String dstState 也是 Json 对象
List<String> dstCities 是 Json 数组

更正 Json 您的 Shipment class 的数据格式类似于

 [{"dstState":"NV" , "dstCities": ["Las Vegas"]}]

或

[{"dstState":"NV" , "dstCities": ["Las Vegas", "Las Not Vegas"]}]

Spring 中的 Jackson Object Mapper 不工作

Jackson Object Mapper in Spring not working

spring

json

spring-mvc

jackson