Question

当我将RestTemplate与String ResponseType一起使用时，它运行正常。

ResponseEntity<String> response = restTemplate.postForEntity(uri,
request, String.class);

返回Json字符串

{"code":0,"message":null,"data":"{\"companyId\":\"1\",\"tinyIdList\":[\"2\"],\"carId\":\"3\"}"}

虽然我使用Java POJO来保存响应，但Java Object的属性都为空

ResponseEntity<queryTinyListResponse> responseEntity = restTemplate.postForEntity(uri, request, queryTinyListResponse.class);

结果：

body:queryTinyListResponse{data=Data{tinyIdList=[], carId='null', companyId='null'}, code=0, msg='null'}

queryTinyListResponse.class：

@JsonIgnoreProperties(ignoreUnknown = true)
public class queryTinyListResponse implements Serializable {
    public class Data{
        private String companyId;
        private List<String> tinyIdList=new ArrayList<String>();
        private String carId;
        //getter setter getCompanyId() etc..

    }
    public Data getData() {
        return data;
    }

    //getter setter
    private  Data data;
    private int code;
    private String msg;
}

Answer 1

您可以在application.properties/yml中使用以下配置：spring.jackson.default-property-inclusion=non_null，然后我尝试重现类似的配置，并在您的响应字符串中找到

{"code":0,"message":null,"data":"{\"companyId\":\"1\",\"tinyIdList\":[\"2\"],\"carId\":\"3\"}"}

一个jeson语法错误，应该为{\"code\":0,\"message\":null,\"data\":{\"companyId\":\"1\",\"tinyIdList\":[\"2\"],\"carId\":\"3\"}}，否则数据字段将被视为字符串而不是数据对象。

如果您想尝试一下自己，可以尝试以下代码：

package com.example.jacksondemo;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.RequestEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

@SpringBootApplication
public class JacksonDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(JacksonDemoApplication.class, args);
    }
}

@lombok.Data
@JsonIgnoreProperties(ignoreUnknown = true)
class QueryTinyListResponse implements Serializable {

    //getter setter
    private  Data data;
    private int code;
    private String msg;
}

@lombok.Data
class Data implements Serializable {
    private String companyId;
    private List<String> tinyIdList=new ArrayList<String>();
    private String carId;
    //getter setter getCompanyId() etc..

}

@RestController
class QueryTinyListResponseController {

    @PostMapping
    public String query(){
        return "{\"code\":0,\"message\":null,\"data\":{\"companyId\":\"1\",\"tinyIdList\":[\"2\"],\"carId\":\"3\"}}";

    }
}


@RestController
class QueryTinyListResponseControllerClient {

    @GetMapping("/client")
    public QueryTinyListResponse query(){
        RestTemplate restTemplate = new RestTemplate();

        return restTemplate.postForEntity("http://localhost:8080/", RequestEntity.EMPTY, QueryTinyListResponse.class).getBody();
    }
}

application.properties

spring.jackson.default-property-inclusion=non_null

Answer 2

我找到了这个问题的答案。我应该使用static内部类here

找到了！！解决方案实际上是很奇怪的。问题来自内部类。旧的结构是这样的：

public class MetaData{
  ...
  public class Data {

     ....

     public class Item{
       ...
     }
   }
}

内部类必须为static，因为Jackson不能直接实例化内部类。

public class MetaData{
  ...
  public static class Data {

     ....

   public static class Item{
       ...
     }
   }
}

一切正常。希望能有所帮助！

Spring Cloud RestTemplate获取空的对象主体（解析Json为空）？

2 个答案: