@Data
@EqualsAndHashCode
@TableName("demo")

public class Demo implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 主鍵
     */
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    /**
     * 身份證號
     */
    @TableField("id_card")
    private String idCard;

    /**
     * 受試者姓名
     */
    @TableField("`name`")
    private String name;

    /**
     * 聯(lián)系電話
     */
    @TableField("phone")
    private String phone;

    /**
     * 入組時間
     */
    @TableField("join_time")
    private Date joinTime;

    /**
     * 狀態(tài)：已入組、已出組、已移除
     */
    @TableField("state")
    private DemoStateEnum state;

    /**
     * 最近一次操作的用戶
     */
    @TableField("last_user")
    private String lastUser;

    /**
     * 關聯(lián)項目ID
     */
    @TableField("project_id")
    private Integer projectId;

    /**
     * 最后一次操作時間
     */
    @TableField("last_update")
    private Date lastUpdate;

    public static Demo builder(){
        return new Demo();
    }
}

public enum DemoStateEnum {

    JOINED("已入組"),
    OUTED("已出組"),
    REMOVED("已移除");
    
    /**
     * 注意這個 @EnumValue注解一定要加上，否則SpringBoot啟動都會報錯，具體原因是因為MybatisePlus實現(xiàn)了根據(jù)這個注解表示實體屬性自動枚舉類型轉(zhuǎn)換。如果找不到就會報錯。
     */
    @EnumValue
    private String state;

    DemoStateEnum(String state){
       this.state = state;
    }
    
    /**
     * @JSONField這個注解解決alibaba.fastjson序列化是枚舉顯示的索引的值，而我們想要的顯示是具體的值：已入組、已出組、已移除等。
     */
    @JSONField
    public String getState() {
        return state;
    }

    @Override
    public String toString() {
        return "DemoStateEnum{" +
                "state='" + state + '\'' +
                '}';
    }
}

CREATE TABLE `demo` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT '主鍵',
  `id_card` varchar(60) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '' COMMENT '身份證號',
  `name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '' COMMENT '受試者姓名',
  `phone` varchar(13) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT '' COMMENT '聯(lián)系電話',
  `join_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '入組時間',
  `state` enum('已入組','已出組','已移除') CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '狀態(tài)：已入組、已出組、已移除',
  `last_user` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '最近一次操作的用戶',
  `project_id` int NOT NULL COMMENT '關聯(lián)項目ID',
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '最后一次操作時間',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='枚舉測試表';

@SpringBootTest
public class DemoTest {

    @Autowired
    private DemoMapper deemoMapper;
    
    //查詢所有demo數(shù)據(jù)
    @Test
    public void querySubject() throws JsonProcessingException {
        List<Demo> demos = deemoMapper.selectList(null);
        System.err.println(JSON.toJSONString(demos));
    }

}

# 根據(jù)上圖細看這句話
Caused by: java.sql.SQLFeatureNotSupportedException
	at com.alibaba.druid.pool.DruidPooledResultSet.getObject(DruidPooledResultSet.java:1771)

public <T> T getObject(String columnLabel, Class<T> type) throws SQLException {
  throw new SQLFeatureNotSupportedException();
}

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.21</version>
</dependency>

public <T> T getObject(String columnLabel, Class<T> type) throws SQLException {
  try {
      // 正常調(diào)用JDBC中的ResultSet了，所以可以正常獲取數(shù)據(jù)，不再出現(xiàn)那個異常了。
      return this.rs.getObject(columnLabel, type);
  } catch (Throwable var4) {
      throw this.checkException(var4);
  }
}

    @JSONField
    public String getState() {
        return state;
    }