iBatis 级联映射双向一对多的使用

以下是项目中使用过的频道(channel)与新闻(news)的对应关系，一个channel下可以有多个news, 一个news必须属于某个channel,在增加一个news的时候必须同时增加一个channel_id在news的数据库表字段上， public class Channel implements Serializable { /** * */ private static final long serialVersionUID = -5876679362585875098L; private int id; private Date create_time; // private String create_man; // private String title; // private String description; // private List<News> news; //一对执有多端的一个集合的引用 getter(); setter(); } */ public class News implements Serializable { /** * */ private static final long serialVersionUID = -6179014966049424520L; private int news_id; private String title; // 新闻标题 private String author; // 作者 private String summary; // private String content; // private Date create_time;// private String source; // private int visit_num; // private int reply_num; private int status; private int order_pos; private String keywords; private Channel channel; //多端执有一端的一个实体引用 public void setChannelId(int channelId){ this.channel.setId(channelId); } public int getChannelId(){ return this.channel.getId(); } // 以上两个方法可以维护它们的映射关系， getter(); setter(); } ibatis中的channel.xml <sqlMap namespace="channel"> <typeAlias alias="channel" type="com.tongdainfo.model.channel.Channel" /> <typeAlias alias="news" type="com.tongdainfo.model.news.News"/> <resultMap id="channelResult" class="channel"> <result property="id" column="id"/> <result property="create_time" column="create_time"/> <result property="create_man" column="create_man"/> <result property="title" column="title"/> <result property="description" column="description"/> <result property="news" column="id" select="getNewsByChannelId" /> </resultMap> <!-- 添加频道 --> <insert id="saveChannel" parameterClass="channel"> <!-- <selectKey keyProperty="id" resultClass="int"> <!--[CDATA[ SELECT LAST_INSERT_ID() AS VALUE ]]> </selectKey> --> <![CDATA[ INSERT INTO channel(title,description,create_man,create_time) VALUES (#title#,#description#,#create_man#,#create_time#) ]]> </insert> </sqlMap> iBatis 中的news.xml <sqlMap namespace="news"> <typeAlias alias="news" type="com.tongdainfo.model.news.News" /> <typeAlias alias="channel" type="com.tongdainfo.model.channel.Channel" /> <resultMap id="newsResult" class="news"> <result property="news_id" column="news_id" /> <result property="title" column="title" /> <result property="author" column="author" /> <result property="summary" column="summary" /> <result property="create_time" column="create_time" /> <result property="source" column="source" /> <result property="visit_num" column="visit_num" /> <result property="reply_num" column="reply_num" /> <result property="status" column="status" /> <result property="order_pos" column="order_pos" /> <result property="keywords" column="keywords" /> <result property="channel.id" column="cid" /> <result property="channel.title" column="ctitle" /> <result property="channel.description" column="cdescription" /> <result property="channel.create_man" column="ccreate_man" /> <result property="channel.create_time" column="ccreate_time" /> </resultMap> <select id="getNewsByChannelId" parameterClass="int" resultMap="newsResult"> select n.news_id as news_id,n.title as title,n.author as author,n.summary as summary, n.create_time as create_time,n.source as source,n.visit_num as visit_num,n.reply_num as reply_num, n.keywords as keywords,c.id as cid,c.title as ctitle,c.description as cdescription,c.creat_man as ccreate_man, c.create_time as ccreate_time from news AS n left join channel as c on n.channel_id =c.id where n.channel_id=#id# </select> <!-- 添加新闻 --> <insert id="saveNews" parameterClass="news"> <!-- <selectKey keyProperty="id" resultClass="int"> <![CDATA[ SELECT LAST_INSERT_ID() AS VALUE ]]> </selectKey> --> <![CDATA[ INSERT INTO News(title,author,summary,content,create_time,source,visit_num,reply_num,status,order_pos,keywords,channel_id) VALUES(#title#,#author#,#summary#,#content#,#create_time#,#source#,#visit_num#,#reply_num#,#status#,#order_pos#,#keywords#,#channelId#) ]]--> </insert> <!-- 查询channel下所有新闻列表 --> <select id="findNewsByChannelId" parameterClass="int" resultMap="newsResult"> select n.news_id as news_id,n.title as title,n.author as author,n.summary as summary, n.create_time as create_time,n.source as source,n.visit_num as visit_num,n.reply_num as reply_num, n.status as status, n.order_pos as order_pos, n.keywords as keywords, c.id as cid,c.title as ctitle,c.description as cdescription,c.create_man as ccreate_man, c.create_time as ccreate_time from news AS n left join channel as c on n.channel_id =c.id where n.channel_id=#id# </select> </sqlMap>