春天開機：沒有字符串參數的構造函數/工廠方法從字符串值反序列化

Question

我試圖讀取與RestTemplate（春季啓動）休息服務的響應：

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

但是當錯誤數組目前對響應：

{ 
    "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" 
} 

我總是得到這樣的錯誤：

2017-07-18 12:29:08.220 WARN 9489 --- [nio-8080-exec-9] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not construct instance of co.easymatch.portals.rightmove.entities.RMError: no String-argument constructor/factory method to deserialize from String value ('MND_00026') at [Source: java.io.PushbackInputStream@77f5bb5f; line: 1, column: 532] (through reference chain: co.portals.entities.RMSendPropertyResponse["errors"]->java.util.ArrayList[0]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of co.portals.entities.RMError: no String-argument constructor/factory method to deserialize from String value ('MND_00026') at [Source: java.io.PushbackInputStream@77f5bb5f; line: 1, column: 532] (through reference chain: co.portals.entities.RMSendPropertyResponse["errors"]->java.util.ArrayList[0])

和我類...

RMSendPropertyResponse類：

@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類：

@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; 
    } 
} 

我不明白爲什麼沒有一個構造函數/工廠方法從字符串值反序列化。

謝謝

Answer 1

您的代碼適用於我。 您正在使用的spring-boot的版本是什麼？你管理自己jackson的版本？如果是的話，你使用的是什麼版本。 你確定你從外部網址獲得的回覆是你在問題中粘貼的內容嗎？ 這裏是我複製的工作代碼：

@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; 
    } 
}