Mybatis 学习-3

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>