Spring Boot MyBatis 将 PostgreSQL 数组转为 Java List

类型处理器

@MappedJdbcTypes({JdbcType.ARRAY})
@MappedTypes({Object.class})
public class ListTypeHandler extends BaseTypeHandler<List<?>> {

    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, List<?> parameter, JdbcType jdbcType) throws SQLException {
        Connection conn = ps.getConnection();
        Array array = conn.createArrayOf(jdbcType.name(), parameter.toArray());
        ps.setArray(i, array);
        array.free();
    }

    @Override
    public List<?> getNullableResult(ResultSet rs, String columnName) throws SQLException {
        return extractArray(rs.getArray(columnName));
    }

    @Override
    public List<?> getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        return extractArray(rs.getArray(columnIndex));
    }

    @Override
    public List<?> getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        return extractArray(cs.getArray(columnIndex));
    }

    protected List<?> extractArray(Array array) throws SQLException {
        if (array == null) {
            return null;
        }
        Object javaArray = array.getArray();
        array.free();
        return new ArrayList<>(Arrays.asList((Object[]) javaArray));
    }
}

YAML 配置

指定类型处理器这个类所在的包的全路径。

mybatis:
  type-handlers-package: z.note.lite.config.mybatis

使用

xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "https://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="z.note.lite.mapper.api.PostMgmtMapper">
    <resultMap id="base" type="z.note.lite.entity.Post">
        <result column="topics" property="topics" typeHandler="z.note.lite.config.mybatis.ListTypeHandler" />
        <result column="images" property="images" typeHandler="z.note.lite.config.mybatis.ListTypeHandler" />
    </resultMap>

</mapper>

@Select

@Mapper
public interface PostMgmtMapper {

    @Select("select * from post where id = #{id}")
    @Results({
            @Result(column = "topics", property = "topics", typeHandler = ListTypeHandler.class),
            @Result(column = "images", property = "images", typeHandler = ListTypeHandler.class)
    })
    Post findById(Integer id);

}