Java 将JSON嵌套到POJO

我试图调用一个外部RESTful web服务，需要解析嵌套JSON附带的响应。我试图解析出以下内容：

{“列表”：[{“列表id”：“abcdef”，“列表名称”：“testing123”}，{“列表id”：“xyz”，“列表名称”：“testing456”}]}

我的POJO类如下所示：

@JsonIgnoreProperties(ignoreUnknown = true)
public class ListGetResponse {
    private String list = "";
    private SMSList lists;

    public String getList() {
        return list;
    }

    public void setList(String list) {
        this.list = list;
    }

    public SMSList getLists() {
        return lists;
    }

    public void setLists(SMSList lists) {
        this.lists = lists;
    }

    @Override
    public String toString() {
        return "SMSListGetResponse [list=" + list + "]";
    }


    @JsonIgnoreProperties(ignoreUnknown = true)
    public class SMSList {
        private String list = "";
        private String list_id = "";
        private String list_name = "";


        public String getList() {
            return list;
        }
        public void setList(String list) {
            this.list = list;
        }
        public String getList_id() {
            return list_id;
        }
        public void setList_id(String list_id) {
            this.list_id = list_id;
        }
        public String getList_name() {
            return list_name;
        }
        public void setList_name(String list_name) {
            this.list_name = list_name;
        }
        @Override
        public String toString() {
            return "SMSList [list_id=" + list_id + ", list_name=" + list_name
                    + "]";
        }


    }

我通过这个方法调用这个函数

public void get()
{
    RestTemplate restTemplate = SMSRestFactory.getRestTemplate();

    ResponseEntity<ListGetResponse> responseEntity = restTemplate.getForEntity(SMS_LIST_GET, ListGetResponse.class);
    ListGetResponse body = responseEntity.getBody();
    System.out.println(responseEntity.getBody());
    System.out.println(body);
}

---

让它发挥作用。将我的SMSList对象更改为列表，并将SMSList类更改为静态类

将SMSList更改为List后，我收到了以下堆栈跟踪：

   Exception in thread "main" org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: No suitable constructor found for type [simple type, class com.em.ustms.sms.list.model.ListGetResponse$SMSList]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@1d1ab77; line: 1, column: 11] (through reference chain: com.em.ustms.sms.list.model.ListGetResponse["list"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class com.em.ustms.sms.list.model.ListGetResponse$SMSList]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@1d1ab77; line: 1, column: 11] (through reference chain: com.em.ustms.sms.list.model.ListGetResponse["list"])
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:228)
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.read(MappingJackson2HttpMessageConverter.java:220)
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:95)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:788)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:773)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:553)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:506)
    at org.springframework.web.client.RestTemplate.getForEntity(RestTemplate.java:268)
    at com.em.ustms.sms.service.SMSListService.get(SMSListService.java:59)
    at com.em.ustms.sms.Application.main(Application.java:12)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class com.em.ustms.sms.list.model.ListGetResponse$SMSList]: can not instantiate from JSON object (need to add/enable type information?)
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@1d1ab77; line: 1, column: 11] (through reference chain: com.em.ustms.sms.list.model.ListGetResponse["list"])
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164)
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1078)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:268)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:124)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:227)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:204)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:23)
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:525)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:99)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:242)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:118)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2993)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2158)
    at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:225)
    ... 9 more

通过将SMSClass更改为静态类解决了此问题：

import java.util.List;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class ListGetResponse {
private List<SMSList> list;

public List<SMSList> getList() {
    return list;
}

public void setList(List<SMSList> list) {
    this.list = list;
}

@Override
public String toString() {
    return "SMSListGetResponse [list=" + list + "]";
}

@JsonIgnoreProperties(ignoreUnknown = true)
public static class SMSList {
    private String list_id = "";
    private String list_name = "";

    public String getList_id() {
        return list_id;
    }
    public void setList_id(String list_id) {
        this.list_id = list_id;
    }
    public String getList_name() {
        return list_name;
    }
    public void setList_name(String list_name) {
        this.list_name = list_name;
    }
    @Override
    public String toString() {
        return "SMSList [list_id=" + list_id + ", list_name=" + list_name
                + "]";
    }


}
}

import java.util.List；
导入com.fasterxml.jackson.annotation.JsonIgnoreProperties；
@JsonIgnoreProperties（ignoreUnknown=true）
公共类ListGetResponse{
私人名单；
公共列表getList（）{
退货清单；
}
公共无效集合列表（列表）{
this.list=列表；
}
@凌驾
公共字符串toString（）{
返回“SMSListGetResponse[list=“+list+”]”；
}
@JsonIgnoreProperties（ignoreUnknown=true）
公共静态类SMSList{
私有字符串列表_id=“”；
私有字符串列表_name=“”；
公共字符串getList_id（）{
返回列表\u id；
}
公共无效集合列表id（字符串列表id）{
this.list\u id=list\u id；
}
公共字符串getList_name（）{
返回列表名称；
}
公共无效集合列表名称（字符串列表名称）{
this.list\u name=list\u name；
}
@凌驾
公共字符串toString（）{
返回“SMSList[list_id=“+list_id+”，list_name=“+list_name
+ "]";
}
}
}

您的响应对象应具有列表类型的列表字段。看看Jackson数据绑定手册：这不是“嵌套JSON”，而是普通的JSON。“嵌套JSON”是指存在编码的JSON字符串作为解码的JSON字符串的元素。

import java.util.List;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class ListGetResponse {
private List<SMSList> list;

public List<SMSList> getList() {
    return list;
}

public void setList(List<SMSList> list) {
    this.list = list;
}

@Override
public String toString() {
    return "SMSListGetResponse [list=" + list + "]";
}

@JsonIgnoreProperties(ignoreUnknown = true)
public static class SMSList {
    private String list_id = "";
    private String list_name = "";

    public String getList_id() {
        return list_id;
    }
    public void setList_id(String list_id) {
        this.list_id = list_id;
    }
    public String getList_name() {
        return list_name;
    }
    public void setList_name(String list_name) {
        this.list_name = list_name;
    }
    @Override
    public String toString() {
        return "SMSList [list_id=" + list_id + ", list_name=" + list_name
                + "]";
    }


}
}