java - Mybatis 映射器到 Mysql Point 对象

Question

我正在开发一个基于空间功能的 Spring boot 服务器。

我被 mybatis 与自定义对象的匹配所困扰。

现在我已经创建了表格，以及一列startLocation，它是Point类型。

CREATE TABLE `vehicle`.`route` (
  `createtime` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP,
  `updatetime` TIMESTAMP NULL,
  `startLocation` POINT NULL,
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`id`));

我的 Route java 对象是

@Table(name = "route")
public class Route extends Base {
    Point startLocation;

    public Location getStartLocation() {
        return startLocation;
    }

    public void setStartLocation(Location startLocation) {
        this.startLocation = startLocation;
    }

   ....other fields
}

我的 Location 对象只保存纬度和经度作为 double 值。

package com.supplyplatform.pojo;

public class Location {
    double Lat;
    double Long;

    public double getLat() {
        return Lat;
    }
    public void setLat(double lat) {
        Lat = lat;
    }
    public double getLong() {
        return Long;
    }
    public void setLong(double l) {
        Long = l;
    }

}

我的 RouteMapper.xml 是

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.supplyplatform.mapper.RouteMapper">
    <resultMap type = "com.supplyplatform.pojo.Route" id="Route">
        <id column="id" jdbcType="INTEGER" property="id" />
        <result column="startpoint" jdbcType="OTHER" property="startLocation" />
    </resultMap>

</mapper> 

并且它不返回类型处理程序异常。 找不到属性 startLocation 的类型处理程序 我已经花了好几天了。预先感谢您。

更新: 我正在尝试在嵌套结果映射之间创建关联。新的 xml 文件是:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.supplyplatform.mapper.RouteMapper">
    <select id="selectRoute" resultMap="Route">
        SELECT *, X(startpoint) as x, Y(startpoint) as y FROM vehicle.vc_route
    </select>
    <resultMap type = "com.supplyplatform.pojo.Route" id="Route">
        <id column="id" jdbcType="INTEGER" property="id" />
        <association property="startLocation" resultMap="Location" />
    </resultMap>
    <resultMap type = "com.supplyplatform.pojo.Location" id="Location">
        <result column="y" property="lat" />
        <result column="x" property="long" />
    </resultMap>
</mapper>

但它始终不返回 Location startLocation 的类型处理程序异常。

Answer 1

Location是一个复杂的类型，那么你必须指定如何映射。

您可以将其分解为 2 个简单类型值:SELECT ST_X(startPoint) as x, ST_Y(startpoint) as y然后映射关联: 请注意，如 this post 中所指定。并在 Mysql doc ，您应该使用 st_x/st_y，因为 x/y 从 Mysql 5.7.6 开始已弃用。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.supplyplatform.mapper.RouteMapper">
    <resultMap type = "com.supplyplatform.pojo.Route" id="Route">
        <id column="id" jdbcType="INTEGER" property="id" />
        <association property="startLocation" resultMap="Location" />
    </resultMap>
    <resultMap type = "com.supplyplatform.pojo.Location" id="Location">
        <result column="y" property="lat" />
        <result column="x" property="long" />
    </resultMap>
</mapper>

或者您可以定义类型处理程序:

public class PointTypeHandler extends org.apache.ibatis.type.BaseTypeHandler<Location> {

  Location getNullableResult(ResultSet rs, String columnName) {
    Location location = new Location();
    Object point = rs.getObject(columnName);
    /* whatever is required to fill Location object */
    return location
  }
}

这是 JDBC 代码，this post may provide some clues .

并在映射中引用它: <result column="startpoint" jdbcType="OTHER" property="startLocation" typeHandler="PointTypeHandler"/>