Mybatis 之TypeHandler

应用自定义Typehandler处理枚举类型

import com.sun.org.apache.bcel.internal.generic.RETURN;

/**
 * 希望数据库保存的是100,200这些状态码，而不是默认0,1或者枚举的名
 * @author lfy
 *
 */
public enum EmpStatus {
	LOGIN(100,"用户登录"),LOGOUT(200,"用户登出"),REMOVE(300,"用户不存在");
	
	
	private Integer code;
	private String msg;
	private EmpStatus(Integer code,String msg){
		this.code = code;
		this.msg = msg;
	}
	public Integer getCode() {
		return code;
	}
	
	public void setCode(Integer code) {
		this.code = code;
	}
	public String getMsg() {
		return msg;
	}
	public void setMsg(String msg) {
		this.msg = msg;
	}
	
	//按照状态码返回枚举对象
	public static EmpStatus getEmpStatusByCode(Integer code){
		switch (code) {
			case 100:
				return LOGIN;
			case 200:
				return LOGOUT;	
			case 300:
				return REMOVE;
			default:
				return LOGOUT;
		}
	}
	
	
}

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;

import com.atguigu.mybatis.bean.EmpStatus;

/**
 * 1、实现TypeHandler接口。或者继承BaseTypeHandler
 * @author lfy
 *
 */
public class MyEnumEmpStatusTypeHandler implements TypeHandler<EmpStatus> {

	/**
	 * 定义当前数据如何保存到数据库中
	 */
	@Override
	public void setParameter(PreparedStatement ps, int i, EmpStatus parameter,
			JdbcType jdbcType) throws SQLException {
		// TODO Auto-generated method stub
		System.out.println("要保存的状态码："+parameter.getCode());
		ps.setString(i, parameter.getCode().toString());
	}

	@Override
	public EmpStatus getResult(ResultSet rs, String columnName)
			throws SQLException {
		// TODO Auto-generated method stub
		//需要根据从数据库中拿到的枚举的状态码返回一个枚举对象
		int code = rs.getInt(columnName);
		System.out.println("从数据库中获取的状态码："+code);
		EmpStatus status = EmpStatus.getEmpStatusByCode(code);
		return status;
	}

	@Override
	public EmpStatus getResult(ResultSet rs, int columnIndex)
			throws SQLException {
		// TODO Auto-generated method stub
		int code = rs.getInt(columnIndex);
		System.out.println("从数据库中获取的状态码："+code);
		EmpStatus status = EmpStatus.getEmpStatusByCode(code);
		return status;
	}

	@Override
	public EmpStatus getResult(CallableStatement cs, int columnIndex)
			throws SQLException {
		// TODO Auto-generated method stub
		int code = cs.getInt(columnIndex);
		System.out.println("从数据库中获取的状态码："+code);
		EmpStatus status = EmpStatus.getEmpStatusByCode(code);
		return status;
	}

}

<typeHandlers>
		<!--1、配置我们自定义的TypeHandler  -->
		<typeHandler handler="com.atguigu.mybatis.typehandler.MyEnumEmpStatusTypeHandler" javaType="com.atguigu.mybatis.bean.EmpStatus"/>
		<!--2、也可以在处理某个字段的时候告诉MyBatis用什么类型处理器
				保存：#{empStatus,typeHandler=xxxx}
				查询：
					<resultMap type="com.atguigu.mybatis.bean.Employee" id="MyEmp">
				 		<id column="id" property="id"/>
				 		<result column="empStatus" property="empStatus" typeHandler=""/>
				 	</resultMap>
				注意：如果在参数位置修改TypeHandler，应该保证保存数据和查询数据用的TypeHandler是一样的。
		  -->
</typeHandlers>