Mybatis 学习-3
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1.设计Dao接口
public interface UserDao {
public boolean addUser(User user);
}
public interface CategoryDao {
public boolean addCategory(Category category);
public Category getCategoryById(int id);
public List<Category> getAllCategorys();
}
public interface ArticleDao {
public boolean addArticle(Article article);
public Article getArticleById(int id);
public List<Article> getAllArticles();
public List<Article> getArticelsByCategory(int categoryId);
public List<Article> getArticlesByTitle(String title);
}
2. 对接口进行实现
public class UserDaoImpl extends BaseDao<User> implements UserDao {
@Override
public boolean addUser(User user) {
try {
super.add(user);
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
}
-------》针对这个配置做映射文件(别忘了在核心配置文件中为实体类添加别名【mybatis.cfg.xml】)
<typeAliases>
<typeAlias alias="User" type="cn.smartapp.blogs.pojo.User"/>
<typeAlias alias="Category" type="cn.smartapp.blogs.pojo.Category "/>
<typeAlias alias="Article" type="cn.smartapp.blogs.pojo.Article"/>
</typeAliases>
User实体类的映射文件
<?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="cn.smartapp.blogs.pojo.User">
<insert id="insertPojo" parameterType="User" useGeneratedKeys="true">
insert into blog_user(user_name,user_pass,nick_name) values(#{userName},#{password},#{nickName})
</insert>
</mapper>
****千万别忘记映射文件写好后，要在核心配置文件中加入映射
<mappers>
<mapper resource="cn/smartapp/blogs/pojo/User.xml"/>
<mapper resource="cn/smartapp/blogs/pojo/Category.xml"/>
<mapper resource="cn/smartapp/blogs/pojo/Article.xml"/>
</mappers>
2.做一个添加User的测试
public class UserDaoAddTest
@Test
public void test() {
UserDao userDao = new UserDaoImpl();
User user = new User();
user.setUserName("mingming");
user.setPassword("123123");
user.setNickName("明明");
boolean doFlag = userDao.addUser(user);
Assert.assertTrue(doFlag);
}
}
3.实现Article一对多双向关联（User，Category）
（1）多对一关联,因为Article是从表，所以Article是多的一方，从这边关联
-》把ArticleDao实现掉（代码就略了，和前面一样）
<?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="cn.smartapp.blogs.pojo.Article">
<resultMap type="Article" id="ArticleResult">
<id column="aid" property="id" />
<result column="art_title" property="title" />
<result column="art_content" property="content" />
<result column="art_pubtime" property="pubTime" javaType="java.util.Date"/>
<association property="User" foreignColumn="pub_user_id">
<id column="uid" property="id" />
<result column="user_name" property="userName" />
<result column="user_pass" property="password" />
<result column="nick_name" property="nickName" />
</association>
<association property="Category" foreignColumn="cate_id">
<id column="cid" property="id" />
<result column="cate_name" property="cateName" />
</association>
</resultMap>
<insert id="insertPojo" parameterType="Article" useGeneratedKeys="true">
insert into blog_article(art_title,art_content,art_pubtime,pub_user_id,cate_id)
values(#{title},#{content},#{pubTime},#{user.id}),#{category.id})
</insert>
<select id="SelectById" resultMap="ArticleResult" parameterType="int">
select
ta.id as aid,
ta.art_title,
ta.art_content,
ta.art_pubtime,
ta.pub_user_id,
ta.cate_id,
tu.id as uid,
tu.user_name,
tu.user_pass,
tu.nick_name,
tc.id as cid,
tc.cate_name
from blog_user as tu inner join blog_article as ta on tu.id=ta.pub_user_id
inner join blog_category as tc on tc.id=ta.cate_id where ta.id=#{id}
</select>
<select id="SelectAll" resultMap="ArticleResult">
select
ta.id as aid,
ta.art_title,
ta.art_content,
ta.art_pubtime,
ta.pub_user_id,
ta.cate_id,
tu.id as uid,
tu.user_name,
tu.user_pass,
tu.nick_name,
tc.id as cid,
tc.cate_name
from blog_user as tu inner join blog_article as ta on tu.id=ta.pub_user_id
inner join blog_category as tc on tc.id=ta.cate_id
</select>
<select id="SelectByCategory" resultMap="ArticleResult">
select
ta.id as aid,
ta.art_title,
ta.art_content,
ta.art_pubtime,
ta.pub_user_id,
ta.cate_id,
tu.id as uid,
tu.user_name,
tu.user_pass,
tu.nick_name,
tc.id as cid,
tc.cate_name
from blog_user as tu inner join blog_article as ta on tu.id=ta.pub_user_id
inner join blog_category as tc on tc.id=ta.cate_id where tc.id=#{cid}
</select>
<select id="SelectByTitle" resultMap="ArticleResult">
select
ta.id as aid,
ta.art_title,
ta.art_content,
ta.art_pubtime,
ta.pub_user_id,
ta.cate_id,
tu.id as uid,
tu.user_name,
tu.user_pass,
tu.nick_name,
tc.id as cid,
tc.cate_name
from blog_user as tu inner join blog_article as ta on tu.id=ta.pub_user_id
inner join blog_category as tc on tc.id=ta.cate_id where ta.title like #{title}
</select>
</mapper>
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