package cn.edu.MyBatisDemo.enums;
//使用枚舉將實體類 User 的 state 屬性設定為三種狀態(tài)
public enum UserState {
    //每個枚舉對象有四種值：索引值（從0開始）、名字（如 OnLine ）、屬性1（如343）、屬性2（如在線）
    OnLine(343,"在線"),
    OffLine(8899,"離線"),
    BeBusy(1414,"忙碌");
    private int code; //定義括號中第一個屬性
    private String msg; //定義括號中第二個屬性
    private UserState(int code,String msg){
        this.code = code;
        this.msg = msg;
    }
    public int getCode() {
        return code;
    }
    public void setCode(int code) {
        this.code = code;
    }
    public String getMsg() {
        return msg;
    }
    public void setMsg(String msg) {
        this.msg = msg;
    }
    //通過 code 值獲取對應的枚舉對象
    public static UserState getUserStateByCode(int code){
        if(code == 343){
            return UserState.OnLine;
        } else if (code == 8899){
            return UserState.OffLine;
        } else {
            return UserState.BeBusy;
        }
    }
}

package cn.edu.MyBatisDemo.test;
import cn.edu.MyBatisDemo.enums.UserState;
import org.junit.Test;
public class EnumTest {
    @Test
    public void enumTest(){
        UserState userState = UserState.OnLine;
        //獲取枚舉對象的四種值
        System.out.println(userState.ordinal()); //索引值
        System.out.println(userState.name()); //名字
        System.out.println(userState.getCode()); //屬性1
        System.out.println(userState.getMsg()); //屬性2
    }
}

package cn.edu.MyBatisDemo.enums;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class CustomTypeHandler implements TypeHandler<UserState> {
    @Override
    public void setParameter(PreparedStatement preparedStatement, int i, UserState userState, JdbcType jdbcType) throws SQLException {
        preparedStatement.setObject(i,userState.getCode());
    }
    @Override
    public UserState getResult(ResultSet resultSet, String s) throws SQLException {
        int code = resultSet.getInt(s);
        return UserState.getUserStateByCode(code);
    }
    @Override
    public UserState getResult(ResultSet resultSet, int i) throws SQLException {
        int code = resultSet.getInt(i);
        return UserState.getUserStateByCode(code);
    }
    @Override
    public UserState getResult(CallableStatement callableStatement, int i) throws SQLException {
        int code = callableStatement.getInt(i);
        return UserState.getUserStateByCode(code);
    }
}

<typeHandlers>
    <typeHandler handler="cn.edu.MyBatisDemo.enums.CustomTypeHandler" javaType="cn.edu.MyBatisDemo.enums.UserState" />
</typeHandlers>