mybatis custom type handler without annoations

问题:

I'm new to mybatis. I am trying to map a JDBC integer to a custom class. All the examples that I have seen on this have used annotations, is it possible to not use annotations and do this? Any example would be greatly appreciated.

Sreekanth

回答1:

It is definitely possible and is described in general in Configuration and in Mapper sections of the documentation.

Define the handler first:

@MappedJdbcTypes(JdbcType.INTEGER)
public class MyClassHandler extends BaseTypeHandler<MyClass> {

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i,
            MyClass parameter, JdbcType jdbcType) throws SQLException {
        ps.setInt(i, parameter.asInt());
    }

    @Override
    public MyClass getNullableResult(ResultSet rs, String columnName)
            throws SQLException {
        int val = rs.getInt(columnName);
        if (rs.wasNull())
            return null;
        else
            return MyClass.valueOf(val);
    }

    @Override
    public MyClass getNullableResult(ResultSet rs, int columnIndex)
            throws SQLException {
        int val = rs.getInt(columnIndex);
        if (rs.wasNull())
            return null;
        else
            return MyClass.valueOf(val);
    }

    @Override
    public MyClass getNullableResult(CallableStatement cs, int columnIndex)
            throws SQLException {
        int val = cs.getInt(columnIndex);
        if (cs.wasNull())
            return null;
        else
            return MyClass.valueOf(val);
    }
}

Then configure it in mybatis-config.xml:

<typeHandlers>
    <typeHandler handler="my.company.app.MyClassHandler"/>
</typeHandlers>

Now you can use it in xml mappers. If you have a class

class SomeTypeEntity {
    private MyClass myClassField;
};

For querying the field configure handler in the resultMap like this:

<resultMap id="someMap" type="SomeTypeEntity">
    <result property="myClassField" column="my_class_column" typeHandler="my.company.app.MyClassHandler"/>
</resultMap>

For insert/update use it like this:

<update id="updateSomeTypeWithMyClassField">
   update some_type
   set
    my_class_column = @{someTypeEntity.myClassField, typeHandler=my.company.app.MyClassHandler},
</update>

for mapper method:

void updateSomeTypeWithMyClassField(@Param("someTypeEntity") SomeTypeEntity entity);