mybatis 自身关联 映射

北极星光

　　使用mybatis的时候遇到关联问题。
　　可以参考如下：
　　一个自关联的model

public class TreeDic  implements java.io.Serializable{
private static final long serialVersionUID = 5454155825314635342L;
//alias
public static final String TABLE_ALIAS = "树形树形字典";
public static final String ALIAS_ID = "编号";
public static final String ALIAS_PARENT_ID = "父节点编号";
public static final String ALIAS_PARENT_IDS = "所有父节点编号";
public static final String ALIAS_TYPE = "分类";
public static final String ALIAS_CODE = "键值";
public static final String ALIAS_NAME = "标签";
public static final String ALIAS_REMARKS = "描述";
public static final String ALIAS_SORT = "排序";
public static final String ALIAS_DEL_FLAG = "del_flag";
public static final String ALIAS_VERSION = "version";
//date formats

private TreeDic parent;
private List<TreeDic> childList = Lists.newArrayList();
//可以直接使用: @Length(max=50,message="用户名长度不能大于50")显示错误消息
//columns START
/**
* id       db_column: id
*/
@Max(9223372036854775807L)
private java.lang.Long id;
/**
* parent_id       db_column: parent_id
*/
@NotNull @Max(9223372036854775807L)
private java.lang.Long parentId;
/**
* parent_ids       db_column: parent_ids
*/
@NotBlank @Length(max=255)
private java.lang.String parentIds;
/**
* type       db_column: type
*/
@Length(max=100)
private java.lang.String type;
/**
* code       db_column: code
*/
@Length(max=100)
private java.lang.String code;
/**
* name       db_column: name
*/
@Length(max=100)
private java.lang.String name;
/**
* remarks       db_column: remarks
*/
@Length(max=255)
private java.lang.String remarks;
/**
* sort       db_column: sort
*/
@Max(9999999999L)
private java.lang.Integer sort;
/**
* del_flag       db_column: del_flag
*/
@Length(max=1)
private java.lang.String delFlag;
/**
* version       db_column: version
*/
@Max(9999999999L)
private java.lang.Integer version;
//columns END
public TreeDic(){
this.delFlag = "0";
this.version = 1;
}
public TreeDic(
java.lang.Long id
){
this.id = id;
}
public void setId(java.lang.Long value) {
this.id = value;
}
public java.lang.Long getId() {
return this.id;
}
public void setParentId(java.lang.Long value) {
this.parentId = value;
}
public java.lang.Long getParentId() {
return this.parentId;
}
public void setParentIds(java.lang.String value) {
this.parentIds = value;
}
public java.lang.String getParentIds() {
return this.parentIds;
}
public void setType(java.lang.String value) {
this.type = value;
}
public java.lang.String getType() {
return this.type;
}
public void setCode(java.lang.String value) {
this.code = value;
}
public java.lang.String getCode() {
return this.code;
}
public void setName(java.lang.String value) {
this.name = value;
}
public java.lang.String getName() {
return this.name;
}
public void setRemarks(java.lang.String value) {
this.remarks = value;
}
public java.lang.String getRemarks() {
return this.remarks;
}
public void setSort(java.lang.Integer value) {
this.sort = value;
}
public java.lang.Integer getSort() {
return this.sort;
}
public void setDelFlag(java.lang.String value) {
this.delFlag = value;
}
public java.lang.String getDelFlag() {
return this.delFlag;
}
public void setVersion(java.lang.Integer value) {
this.version = value;
}
public java.lang.Integer getVersion() {
return this.version;
}

/**
* @return Returns the parent.
*/
public TreeDic getParent() {
return parent;
}
/**
* @param parent The parent to set.
*/
public void setParent(TreeDic parent) {
this.parent = parent;
}
/**
* @return Returns the childList.
*/
public List<TreeDic> getChildList() {
return childList;
}
/**
* @param childList The childList to set.
*/
public void setChildList(List<TreeDic> childList) {
this.childList = childList;
}
public static void sortList(List<TreeDic> list, List<TreeDic> sourcelist, Long parentId){
for (int i=0; i<sourcelist.size(); i++){
TreeDic e = sourcelist.get(i);
if (e.getParent()!=null && e.getParent().getId()!=null
&& e.getParent().getId().equals(parentId)){
list.add(e);
// 判断是否还有子节点, 有则继续获取子节点
for (int j=0; j<sourcelist.size(); j++){
TreeDic childe = sourcelist.get(j);
if (childe.getParent()!=null && childe.getParent().getId()!=null
&& childe.getParent().getId().equals(e.getId())){
sortList(list, sourcelist, e.getId());
break;
}
}
}
}
}
public boolean isRoot(){
return isRoot(this.id);
}
public static boolean isRoot(Long id){
return id != null && id.equals(1L);
}
public String toString() {
return ToStringBuilder.reflectionToString(this);
}
public int hashCode() {
return new HashCodeBuilder()
.append(getId())
.toHashCode();
}
public boolean equals(Object obj) {
if(obj instanceof TreeDic == false) return false;
if(this == obj) return true;
TreeDic other = (TreeDic)obj;
return new EqualsBuilder()
.append(getId(),other.getId())
.isEquals();
}
}
　　Mapper文件的配置很重要：

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"
"http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">

<!-- 不使用namespace的话sql搜索定位会比较方便 -->
<mapper namespace="TreeDic">
<resultMap id="RM.TreeDic" type="net.cciot.snail.sys.model.TreeDic">
<result property="id" column="id"/>
<result property="parentId" column="parent_id"/>
<result property="parentIds" column="parent_ids"/>
<result property="type" column="type"/>
<result property="code" column="code"/>
<result property="name" column="name"/>
<result property="remarks" column="remarks"/>
<result property="sort" column="sort"/>
<result property="delFlag" column="del_flag"/>
<result property="version" column="version"/>
<!-- 查询父模块 -->  
<association property="parent" column="parent_id" select="TreeDic.getById" />
<!-- 查询子模块 -->  
<collection property="childList" column="id" select="TreeDic.getChildList" />  
</resultMap>
<!-- 用于select查询公用抽取的列 -->
<sql id="TreeDic.columns">
<![CDATA[
id,parent_id,parent_ids,type,code,name,remarks,sort,del_flag,version
]]>
</sql>
<!-- useGeneratedKeys="true" keyProperty="xxx" for sqlserver and mysql -->
<insert id="TreeDic.insert" useGeneratedKeys="true" keyProperty="id">
<![CDATA[
INSERT INTO sys_tree_dic (
id, parent_id, parent_ids, type, code, name, remarks, sort, del_flag, version
) VALUES (
#{id}, #{parentId}, #{parentIds}, #{type}, #{code}, #{name}, #{remarks}, #{sort}, #{delFlag}, #{version}        
)
]]>
<!--
oracle: order="BEFORE" SELECT sequenceName.nextval AS ID FROM DUAL
DB2: order="BEFORE"" values nextval for sequenceName
<selectKey resultType="java.lang.Long" order="BEFORE" keyProperty="userId">
SELECT sequenceName.nextval AS ID FROM DUAL
</selectKey>
-->
</insert>
<update id="TreeDic.update" >
<![CDATA[
UPDATE sys_tree_dic SET
parent_id = #{parentId} , parent_ids = #{parentIds} , type = #{type} , code = #{code} , name = #{name} , remarks = #{remarks} , sort = #{sort} , del_flag = #{delFlag} , version = version + 1
WHERE
id = #{id}         
]]>
</update>
<delete id="TreeDic.delete">
<![CDATA[
UPDATE sys_tree_dic SET
del_flag = '1'
WHERE
id = #{id}
]]>
</delete>
<select id="TreeDic.getById" resultMap="RM.TreeDic">
SELECT <include refid="TreeDic.columns" />
<![CDATA[
FROM sys_tree_dic
WHERE
id = #{id}
]]>
</select>
<select id="TreeDic.getChildList" resultMap="RM.TreeDic">
SELECT <include refid="TreeDic.columns" />
<![CDATA[
FROM sys_tree_dic
WHERE
parent_id = #{id}
]]>
</select>

<sql id="TreeDic.findPage.where">
<!-- ognl访问静态方法的表达式 为@class@method(args),以下为调用rapid中的Ognl.isNotEmpty()方法,还有其它方法如isNotBlank()可以使用，具体请查看Ognl类 -->
<where>      
<if test="@Ognl@isNotEmpty(id)">
AND id = #{id}
</if>
<if test="@Ognl@isNotEmpty(parentId)">
AND parent_id = #{parentId}
</if>
<if test="@Ognl@isNotEmpty(parentIds)">
AND parent_ids = #{parentIds}
</if>
<if test="@Ognl@isNotEmpty(type)">
AND type = #{type}
</if>
<if test="@Ognl@isNotEmpty(code)">
AND code = #{code}
</if>
<if test="@Ognl@isNotEmpty(name)">
AND name = #{name}
</if>
<if test="@Ognl@isNotEmpty(remarks)">
AND remarks = #{remarks}
</if>
<if test="@Ognl@isNotEmpty(sort)">
AND sort = #{sort}
</if>
<if test="@Ognl@isNotEmpty(delFlag)">
AND del_flag = #{delFlag}
</if>
<if test="@Ognl@isNotEmpty(version)">
AND version = #{version}
</if>
</where>
</sql>
<select id="TreeDic.findPage.count" resultType="long">
SELECT count(*) FROM sys_tree_dic
<include refid="TreeDic.findPage.where"/>   
</select>
<!--
分页查询已经使用Dialect进行分页,也可以不使用Dialect直接编写分页
因为分页查询将传 offset,pageSize,lastRows 三个参数,不同的数据库可以根于此三个参数属性应用不同的分页实现
-->
<select id="TreeDic.findPage" resultMap="RM.TreeDic">
SELECT <include refid="TreeDic.columns" />
FROM sys_tree_dic
<include refid="TreeDic.findPage.where"/>
<if test="@Ognl@isNotEmpty(sortColumns)">
ORDER BY ${sortColumns}
</if>
<if test="offset != null and pageSize != null" >
<![CDATA[ limit #{offset} , #{pageSize} ]]>
</if>
</select>

</mapper>

　　总结与此，方便下次使用