SrpingMVC/SpringBoot中restful接口序列化json的时候使用Jackson将空字段，空字符串不传递给前端

笔者的JSON如下：

{
    "code": 10001,
    "message": "成功",
    "nextUrl": null,
    "data": {
        "updateTime": "2020-02-23 13:43:18",
        "result": [
            {
                "confirm": 24,
                "suspect": 0,
                "dead": 0,
                "heal": 17,
                "weight": 18.8,
                "mapId": null,
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 19,
                "suspect": 0,
                "dead": 0,
                "heal": 14,
                "weight": 15.1,
                "mapId": "c320500_2",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 10,
                "suspect": 0,
                "dead": 0,
                "heal": 7,
                "weight": 7.8,
                "mapId": "c320500_4",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 8,
                "suspect": 0,
                "dead": 0,
                "heal": 6,
                "weight": 6.4,
                "mapId": "c320500_7",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 6,
                "suspect": 0,
                "dead": 0,
                "heal": 3,
                "weight": 4.2,
                "mapId": "c320500_8",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 6,
                "suspect": 0,
                "dead": 0,
                "heal": 2,
                "weight": 3.8,
                "mapId": null,
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 5,
                "suspect": 0,
                "dead": 0,
                "heal": 4,
                "weight": 4.1,
                "mapId": "c320500_5",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 4,
                "suspect": 0,
                "dead": 0,
                "heal": 3,
                "weight": 3.2,
                "mapId": "c320500_0",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 3,
                "suspect": 0,
                "dead": 0,
                "heal": 1,
                "weight": 1.9,
                "mapId": "c320500_3",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 2,
                "suspect": 0,
                "dead": 0,
                "heal": 0,
                "weight": 1,
                "mapId": "c320500_6",
                "updateTime": "2020-02-25 18:17:14"
            },
            {
                "confirm": 0,
                "suspect": 0,
                "dead": 0,
                "heal": 2,
                "weight": 0.8,
                "mapId": null,
                "updateTime": "2020-02-26 11:56:04"
            }
        ]
    }
}

里面有mapId这个字段，多处都为null，在大json考虑网络传输速度的情况下，这些null字段是多余的。

springmvc/springBoot中json框架默认使用Jackson，我们就可以通过Jackson相关注解来过滤字段为null的字段。

只要加

@JsonInclude(JsonInclude.Include.NON_EMPTY)

对应java类Snapshot.java

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.google.common.base.Objects;
import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.apache.ibatis.type.JdbcType;
import tk.mybatis.mapper.annotation.ColumnType;

import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.Transient;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
@Table(name = "snapshot")
public class SnapShot {

    @JsonIgnore
    @Id
    @GeneratedValue(generator = "JDBC")
    private Integer id;

    @JsonIgnore
    private Integer distId;

    private Integer confirm;

    private Integer suspect;

    private Integer dead;

    @JsonIgnore
    private String deadRate;

    private Integer heal;
    @ColumnType(column = "`weight`",jdbcType = JdbcType.FLOAT)
    private Float weight;
    @JsonIgnore
    private Float riskLevel = 0.0f;

    @JsonIgnore
    private String healRate;

    @JsonIgnore
    @Transient
    //@ColumnType(column = "`level`",jdbcType = JdbcType.VARCHAR)
    private String level;

    @JsonInclude(JsonInclude.Include.NON_EMPTY)
    private String mapId;

    private String updateTime;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        SnapShot snapShot = (SnapShot) o;
        return Objects.equal(distId, snapShot.distId) &&
                Objects.equal(confirm, snapShot.confirm) &&
                Objects.equal(suspect, snapShot.suspect) &&
                ("area".equals(level)?
                        Objects.equal(suspect, snapShot.suspect):
                        true) &&
                Objects.equal(dead, snapShot.dead) &&
                Objects.equal(heal, snapShot.heal);
    }

    @Override
    public int hashCode() {
        return 0;
    }
}

设置后效果如下：

转载自：https://www.cnblogs.com/yangy608/p/3936848.html