2025年7月工作经验记录

1 Jackson反序列化问题

遇到了这样的问题：

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org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class com.caacsri.route.domain.vo.RouteBindingVO]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of com.xxx.route.domain.vo.RouteBindingVO (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `com.xxx.route.domain.vo.RouteBindingVO` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

相关代码：

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@PostMapping("/updateBinding")
public AjaxResult updateBinding(
        @RequestBody RouteBindingVO routeBindingVO
) {
    return AjaxResult.success(airportRoutePlanService.updateBinding(routeBindingVO));
}
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@AllArgsConstructor // 只有全参构造器
@Data
public class RouteBindingVO {
    private String callSign;

    private String routeId;
}

原因：

  1. @RequestBody 默认使用 Jackson 进行 JSON 反序列化；
  2. Jackson 进行 JSON 反序列化时需要无参构造器，步骤：
    1. 通过无参构造器 new 一个对象实例；
    2. 用反射设置每个字段的值（或通过 setter 方法）；

修改：提供无参构造器

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@AllArgsConstructor // 只有全参构造器
@NoArgsConstructor // 提供无参构造器
@Data
public class RouteBindingVO {
    private String callSign;

    private String routeId;
}

或者使用 @JsonCreator + @JsonProperty，告诉 Jackson 用某个有参构造器

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@JsonCreator
public RouteBindingVO(@JsonProperty("callSign") String callSign,
                      @JsonProperty("routeId") String routeId) {
    this.callSign = callSign;
    this.routeId = routeId;
}