How to customize type converters in MyBatis?

In MyBatis, you can customize type converters by implementing the TypeHandler interface. Here is an example of a custom type converter:

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<CustomType> {

    @Override
    public void setParameter(PreparedStatement ps, int i, CustomType parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, parameter.toString());
    }

    @Override
    public CustomType getResult(ResultSet rs, String columnName) throws SQLException {
        return CustomType.valueOf(rs.getString(columnName));
    }

    @Override
    public CustomType getResult(ResultSet rs, int columnIndex) throws SQLException {
        return CustomType.valueOf(rs.getString(columnIndex));
    }

    @Override
    public CustomType getResult(CallableStatement cs, int columnIndex) throws SQLException {
        return CustomType.valueOf(cs.getString(columnIndex));
    }
}

In the above example, CustomType is a custom enum type. We have implemented the TypeHandler interface and overridden the setParameter and getResult methods to achieve conversion between custom types and database fields.

Next, it is necessary to register the custom type converter in the MyBatis configuration file.

<typeHandlers>
    <typeHandler handler="com.example.CustomTypeHandler"/>
</typeHandlers>

This way, you can use custom type handlers in MyBatis to handle the conversion between database fields and Java objects.