can only instantiate non-static inner class by using default, no-argument constructor
Jackson解析嵌套类问题
- 问题描述
- 解决方法
问题描述
调用接口返回json格式的数据，使用Jackson解析参数转换成对象：
AjaxResult<PointGoodsResponse> getPointGoodsList(@RequestBody PointGoodsQuery query);
@ApiModel(value = "PointGoodsResponse",description = "积分商品信息")
public class PointGoodsResponse implements Serializable {
private static final long serialVersionUID = 4790924204646750015L;
@ApiModelProperty(value = "总条数", dataType = "Integer")
private Integer totalCount;
@ApiModelProperty(value = "商品列表", dataType = "list")
private List<PointGoodsResponse.PointGoods> data = Lists.newArrayList();
public class PointGoods {
@ApiModelProperty(value = "商品ID", dataType = "Long")
private Long productId;
@ApiModelProperty(value = "商品名称", dataType = "String")
private String productName;
@ApiModelProperty(value = "所需积分", dataType = "Long")
private Long points;
@ApiModelProperty(value = "集团id", dataType = "Integer")
private Integer brandId;
@ApiModelProperty(value = "酒店id", dataType = "Integer")
private Integer hotelId;
@ApiModelProperty(value = "产品价值，单位：分", dataType = "Long")
private Long price;
@ApiModelProperty(value = "过期时间", dataType = "String")
private String expireDate;
@ApiModelProperty(value = "生效时间", dataType = "String")
private String effectiveDate;
@ApiModelProperty(value = "产品数量", dataType = "Integer")
private Integer count;
@ApiModelProperty(value = "已兑换数量", dataType = "Integer")
private Integer exchangedCount;
@ApiModelProperty(value = "已使用数量", dataType = "Integer")
private Integer usedCount;
@ApiModelProperty(value = "产品头图片", dataType = "String")
private String image;
//getter、setter方法
...
}
//getter、setter方法
...
}
调用该接口，返回错误信息：
"message": "JSON parse error: Can not construct instance of com.zkt.user.api.model.point.PointGoodsResponse$PointGoods: can only instantiate non-static inner class by using default, no-argument constructor; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.zkt.user.api.model.point.PointGoodsResponse$PointGoods: can only instantiate non-static inner class by using default, no-argument constructor at [Source: java.io.PushbackInputStream@edc246; line: 20, column: 9] (through reference chain: com.zkt.user.api.model.point.PointGoodsResponse["data"]->com.zkt.user.api.model.point.PointGoodsResponse$PointGoods["data"]->java.util.ArrayList[0]**)",
解决方法
问题本质为：内部非静态类无法实例化
你需要做两件事：
- 给内部类前面加上static
- 给内部类加上默认构造函数
改过后的内部类像这样：
@ApiModel(value = "PointGoodsResponse",description = "积分商品信息")
public class PointGoodsResponse implements Serializable {
private static final long serialVersionUID = 4790924204646750015L;
@ApiModelProperty(value = "总条数", dataType = "Integer")
private Integer totalCount;
@ApiModelProperty(value = "商品列表", dataType = "list")
private List<PointGoodsResponse.PointGoods> data = Lists.newArrayList();
public static class PointGoods {
public PointGoods() {
}
@ApiModelProperty(value = "商品ID", dataType = "Long")
private Long productId;
@ApiModelProperty(value = "商品名称", dataType = "String")
private String productName;
@ApiModelProperty(value = "所需积分", dataType = "Long")
private Long points;
@ApiModelProperty(value = "集团id", dataType = "Integer")
private Integer brandId;
@ApiModelProperty(value = "酒店id", dataType = "Integer")
private Integer hotelId;
@ApiModelProperty(value = "产品价值，单位：分", dataType = "Long")
private Long price;
@ApiModelProperty(value = "过期时间", dataType = "String")
private String expireDate;
@ApiModelProperty(value = "生效时间", dataType = "String")
private String effectiveDate;
@ApiModelProperty(value = "产品数量", dataType = "Integer")
private Integer count;
@ApiModelProperty(value = "已兑换数量", dataType = "Integer")
private Integer exchangedCount;
@ApiModelProperty(value = "已使用数量", dataType = "Integer")
private Integer usedCount;
@ApiModelProperty(value = "产品头图片", dataType = "String")
private String image;
//getter、setter方法
...
}
//getter、setter方法
...
}