Spring Boot：没有从字符串值反序列化的字符串参数构造函数/工厂方法

Question

我正在尝试使用 RestTemplate (Spring Boot) 读取来自休息服务的响应：

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<RMSendPropertyResponse> response = restTemplate.exchange("https://url", HttpMethod.POST, entity, RMSendPropertyResponse.class);
RMSendPropertyResponse rmResponse = response.getBody();

但是当响应中存在错误数组时：

{
    "message": "Something failed.",
    "success": false,
    "errors": [
        {
            "error_code": "MND_00026",
            "error_value": "",
            "error_description": "field not present"
        },
        {
            "error_code": "VAL_00039",
            "error_value": "0",
            "error_description": "Wrong field"
        }
    ],
    "warnings": null,
    "request_timestamp": "18-07-2017 11:34:46",
    "response_timestamp": "18-07-2017 11:34:46"
}

我总是收到这个错误：

2017-07-18 12:29:08.220 WARN 9489 --- [nio-8080-exec-9] .wsmsDefaultHandlerExceptionResolver：无法读取 HTTP 消息：org.springframework.http.converter.HttpMessageNotReadableException：无法读取文档：无法构造 co.easymatch.portals.rightmove.entities.RMError 的实例：在 [来源：java.io.PushbackInputStream@77f5bb5f; 没有从字符串值 ('MND_00026') 反序列化的字符串参数构造函数/工厂方法；行：1，列：532]（通过参考链：co.portals.entities.RMSendPropertyResponse["errors"]->java.util.ArrayList[0]）；嵌套异常是 com.fasterxml.jackson.databind.JsonMappingException：无法构造 co.portals.entities.RMError 的实例：没有从字符串值反序列化的字符串参数构造函数/工厂方法（'MND_00026' ) 在 [来源：java.io.PushbackInputStream@77f5bb5f; 行：1，列：532]（通过参考链：co.portals.entities.RMSendPropertyResponse["errors"]->java.util.ArrayList[0]）

而我的课...

RMSendPropertyResponse 类：

@JsonIgnoreProperties(ignoreUnknown = true)
public class RMSendPropertyResponse extends RMResponse {
    private RMPropertyResponse property;
    private List<RMWarning> warnings;
    private List<RMError> errors;

    public RMSendPropertyResponse() {
    }

    public RMPropertyResponse getProperty() {
        return property;
    }

    public void setProperty(RMPropertyResponse property) {
        this.property = property;
    }

    public List<RMWarning> getWarnings() {
        return warnings;
    }

    public void setWarnings(List<RMWarning> warnings) {
        this.warnings = warnings;
    }

    public List<RMError> getErrors() {
        return errors;
    }

    public void setErrors(List<RMError> errors) {
        this.errors = errors;
    }
}

RMError 类：

@JsonIgnoreProperties(ignoreUnknown = true)
public class RMError {
    private String error_code;
    private String error_description;
    private String error_value;

    public RMError() {
    }

    public String getError_code() {
        return error_code;
    }

    public void setError_code(String error_code) {
        this.error_code = error_code;
    }

    public String getError_description() {
        return error_description;
    }

    public void setError_description(String error_description) {
        this.error_description = error_description;
    }

    public String getError_value() {
        return error_value;
    }

    public void setError_value(String error_value) {
        this.error_value = error_value;
    }
}

我不明白为什么没有从 String 值反序列化的构造函数/工厂方法。

谢谢

Answer 1

你的代码对我有用。spring-boot您使用的是什么版本？你管理自己jackson的版本吗？如果是的话，您使用的是什么版本。您确定从您调用的外部网址获得的响应就是您粘贴在问题中的内容吗？这是我复制的工作代码：

@RestController
public class MyController {  

 @GetMapping(value = "/read", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity read() {
    RestTemplate restTemplate = new RestTemplate();
    ResponseEntity<RMSendPropertyResponse> response = restTemplate.exchange("http://localhost:8080/", HttpMethod.GET, null, RMSendPropertyResponse.class);
    RMSendPropertyResponse rmResponse = response.getBody();
    return new ResponseEntity<>(rmResponse, HttpStatus.CREATED);

}

@GetMapping(value = "/", produces = MediaType.APPLICATION_JSON_VALUE)
public String get() {
    return "{\n" +
            "    \"message\": \"Something failed.\",\n" +
            "    \"success\": false,\n" +
            "    \"errors\": [\n" +
            "        {\n" +
            "            \"error_code\": \"MND_00026\",\n" +
            "            \"error_value\": \"\",\n" +
            "            \"error_description\": \"field not present\"\n" +
            "        },\n" +
            "        {\n" +
            "            \"error_code\": \"VAL_00039\",\n" +
            "            \"error_value\": \"0\",\n" +
            "            \"error_description\": \"Wrong field\"\n" +
            "        }\n" +
            "    ],\n" +
            "    \"warnings\": null,\n" +
            "    \"request_timestamp\": \"18-07-2017 11:34:46\",\n" +
            "    \"response_timestamp\": \"18-07-2017 11:34:46\"\n" +
            "}";
  }

}

@JsonIgnoreProperties(ignoreUnknown = true)
class RMError {
    private String error_code;
    private String error_description;
    private String error_value;

    public RMError() {
    }

    public String getError_code() {
        return error_code;
    }

    public void setError_code(String error_code) {
        this.error_code = error_code;
    }

    public String getError_description() {
        return error_description;
    }

    public void setError_description(String error_description) {
        this.error_description = error_description;
    }

    public String getError_value() {
        return error_value;
    }

    public void setError_value(String error_value) {
        this.error_value = error_value;
    }
}

@JsonIgnoreProperties(ignoreUnknown = true)
class RMSendPropertyResponse {

    private List<RMError> errors;

    public RMSendPropertyResponse() {
    }

    public List<RMError> getErrors() {
        return errors;
    }

    public void setErrors(List<RMError> errors) {
        this.errors = errors;
    }
}