mybatis中树形结构的bean的关系映射

Posted 2020-08-24 静女神

最近用mybatis写一个小程序，涉及到树形结构的关系映射，比如一个分类，本身具有多对一的关系，那么它是如何映射呢？直接贴代码：

Cate.java

@Table(name="cate")
public class Cate extends AbstractModel {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private Long id;
	private String name;
	
	private String mark;
	private String img;
	private Long pid;
	public Cate() {
		super();
	}
	private Date insertTime;
	private int sortNum;
	private String intro;
	private List<Cate> ch = new ArrayList<Cate>();
	private Cate parentCate;
	private int status;
	
	public String getImg() {
		return img;
	}
	public void setImg(String img) {
		this.img = img;
	}
	public Date getInsertTime() {
		return insertTime;
	}
	public void setInsertTime(Date insertTime) {
		this.insertTime = insertTime;
	}
	public int getSortNum() {
		return sortNum;
	}
	public void setSortNum(int sortNum) {
		this.sortNum = sortNum;
	}
	public String getIntro() {
		return intro;
	}
	public void setIntro(String intro) {
		this.intro = intro;
	}
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public Cate(String name) {
		super();
		this.name = name;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getMark() {
		return mark;
	}
	public void setMark(String mark) {
		this.mark = mark;
	}
	public Long getPid() {
		return pid;
	}
	public void setPid(Long pid) {
		this.pid = pid;
	}
	public List<Cate> getCh() {
		return ch;
	}
	public void setCh(List<Cate> ch) {
		this.ch = ch;
	}
	
	public Cate getParentCate() {
		return parentCate;
	}
	public void setParentCate(Cate parentCate) {
		this.parentCate = parentCate;
	}
	public int getStatus() {
		return status;
	}
	public void setStatus(int status) {
		this.status = status;
	}
	
}

 Cate.xml

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cxgt.mvc.gede.dao.CateDao">
  <resultMap type="com.cxgt.mvc.gede.pojo.Cate" id="cateResult">  
        <id column="id" property="id"/>  
        <result column="name" property="name"/>  
        <result column="pid" property="pid"/>   
        <result column="mark" property="mark"/>  
        <result column="img" property="img"/> 
        <result column="insertTime" property="insertTime"/>  
        <result column="intro" property="intro"/>  
        <result column="sortNum" property="sortNum"/>  
        <result column="status" property="status"/>  
        <!-- 多对一的关系 -->  
        <!-- property: 指的是属性的值, javaType：指的是属性的类型-->  
        <association property="parentCate" javaType="com.cxgt.mvc.gede.pojo.Cate" column="pid" select="get">  
        </association>  
         <collection property="ch" ofType="com.cxgt.mvc.gede.pojo.Cate" column="id" select="getCh">  
        </collection>  
    </resultMap>  
	<!-- 单行插入 -->
	<insert id="insert" parameterType="com.cxgt.mvc.gede.pojo.Cate">
		INSERT INTO
			cate
		(
			name,
			pid,
			mark,
			img,
			insertTime,
            intro,
            sortNum,
            status
            
		) 
			VALUES 
		(
			#{name},
			#{pid},
			#{mark},
			#{img},
			#{insertTime},
			#{intro},
			#{sortNum},
			#{status}
		)
	</insert>
	 <!-- 删除用户 -->  
    <delete id="delete" parameterType="java.lang.Long">  
        delete from cate where id=#{id}  
    </delete>  
    <select id="get" resultMap="cateResult">
        select * from cate where id=#{id}
    </select>
     <select id="findAll" resultMap="cateResult">
        select * from cate where pid is null;
    </select>
     <select id="getCh" parameterType="java.lang.Long" resultMap="cateResult"><!-- resultType="com.cxgt.mvc.gede.pojo.Cate" -->
        select * from cate where pid=#{pid};
    </select>
     <update id="update" parameterType="com.cxgt.mvc.gede.pojo.Cate" >
    update cate
    set name = #{name,jdbcType=VARCHAR},
      pid = #{pid,jdbcType=BIGINT},
      mark = #{mark,jdbcType=VARCHAR},
      img = #{img,jdbcType=VARCHAR},
      insertTime = #{insertTime,jdbcType=DATE},
      intro = #{intro,jdbcType=VARCHAR},
      sortNum = #{sortNum,jdbcType=INTEGER},
      status = #{status,jdbcType=INTEGER}
    where id = #{id,jdbcType=BIGINT}
  </update>
</mapper>

这样就可以啦，树形结构就可以出现啦~