MyBatis-快速入门

UserMapper userMapper =session.getMapper(UserMapper.class);
List<User> userList =userMapper.getList();

<resultMap id="LimitType" type="User">
    <result column="address" property="addes"/>
</resultMap>
<select id="getUserByLimit" parameterType="map" resultMap="LimitType">
    select * from user limit #{startIndex},#{pageSize}
</select>

@Test
public void getUserByLimit(){
    SqlSession sqlSession = SqlSessionFactoryUtil.openSqlSession();
    UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
    Map map = new HashMap<String , Integer>();
    map.put("startIndex", 0);
    map.put("pageSize",2);
    List <User> list=userMapper.getUserByLimit(map);
    for (User s :list) {
        System.out.println(s);
    }
    sqlSession.close();
}

RowBounds rowBoun RowBounds rowBounds= new RowBounds(0,5);
List<User> list = sqlSession.selectList("com.ybzn.dao.UserMapper.getUserByLimit", null,rowBounds);

<resultMap id="LimitType" type="User">
    <result column="address" property="addes"/>
</resultMap>
<select id="getUserByLimit" parameterType="map" resultMap="LimitType">
    select * from user 
</select>

  <select id="getStudent" resultMap="StudentTeacher">
        select * from new_user;
  </select>
    <resultMap id="StudentTeacher" type="Student">
        <result column="id" property="id"></result>
        <result column="stuname" property="stuname"></result>
        <result column="id" property="id"></result>
        <!--    复杂的属性 需要单独处理    对象：association     集合：collection     -->
        <association property="teacher" column="tid"
                             javaType="Teacher" select="getTeacher"/>
    </resultMap>
    <select id="getTeacher" resultType="Teacher">
        select * from teacher where tid=#{tid}
    </select>

<select id="getStudent2" resultMap="StudentTeacher2">
    select s.id sid,s.stuname sname,s.stuclass sclass,t.teaname tname from new_user s,teacher t where s.tid=t.tid;
</select>
<resultMap id="StudentTeacher2" type="Student">
    <result column="sid" property="id"></result>
    <result column="sname" property="stuname"></result>
    <result column="sclass" property="stuclass"></result>
    <association property="teacher" javaType="Teacher">
        <result property="teaname" column="tname"></result>
    </association>
      //其中association 里面的property对应Pojo中的字段名 
     //javaType 对应pojo中的字段名类型
     //配置中所有property 表示数据库中的字段名，Column表示程序中的别名或者字段名
</resultMap>

@Data public class Student { 
private int id; private String stuname;
 private String stuclass; 
private Teacher teacher; }  

 1 <!--按照结果来嵌套查询-->
 2 <select id="getTeacher" resultMap="TeacherStudent">
 3     select s.id  sid, s.stuname sname, s.stuclass sclass, t.teaname tname , t.tid tid
 4     from new_user s , teacher t
 5     where s.tid = t.tid and t.tid = #{tid};
 6 </select>
 7 <resultMap id="TeacherStudent" type="Teacher">
 8     <result column="tname" property="teaname"></result>
 9     <!--    复杂的属性 需要单独处理    对象：association     集合：collection
10             javaType="" 指定属性的类型
11             集合中的泛型信息 ，我们可以通过ofType获取
12       -->
13     <collection property="student" ofType="Student">
14         <result property="id" column="sid"></result>
15         <result property="stuname" column="sname"></result>
16         <result property="tid" column="tid"></result>
17         <result property="stuclass" column="sclass"></result>
18     </collection>
19 </resultMap>

@Data
public class Teacher{
  private int tid;
    private String teaname;
    private List<Student> student;
    } 

<select id="queryBlogIF" parameterType="map" resultType="blog">
    select * from blog 
    <where>
    <if test="title != null">
            and title = #{title}
    </if>
    <if test="author != null">
            and author = #{author}
    </if>
    </where>
</select>

<select id="queryBlogChoose" parameterType="map" resultType="blog">
    select * from blog
    <where>
        <choose>
            <when test="title !=null">
                title=#{title}
            </when>
            <when test="author != null">
                and author=#{author}
            </when>
            <otherwise>
               and views=#{views}
            </otherwise>
        </choose>
    </where>
</select>

<update id="updateBlog" parameterType="map">
    update  blog
    <set>
        <if test="title !=null">
            title = #{title},
        </if>
        <if test="author !=null ">
            author = #{author},
        </if>
    </set>
    where id= #{id}
</update>

<sql id="if-title-author">
    <if test="title != null">
        title = #{title}
    </if>
    <if test="author != null">
        and author = #{author}
    </if>
</sql>

   <!-- 传递一个万能的map, 这个Map可以存在一个集合-->
<select id="queryBlogForeach" parameterType="map" resultType="Blog">
    select * from blog
    <where>
        <foreach collection="ids" item="flagid"
        open="and (" close=")" separator="or">
            id=#{flagid}
        </foreach>
    </where>
</select>

@Test
public  void sqlSelect(){
    SqlSession session = SqlSessionFactoryUtil.openSqlSession();
    BlogMapper mapper = session.getMapper(BlogMapper.class);
    HashMap map = new HashMap();
    ArrayList <String> ids = new ArrayList <>();
    ids.add("1");
    ids.add("2");
    ids.add("3");
    ids.add("4");
    map.put("ids", ids);
    List <Blog> blogs = mapper.queryBlogForeach(map);
    for (Blog blog : blogs) {
        System.out.println(blog);
    }
}

<setting name="cacheEnabled" value="true"/>

<cache/>
<cache
  eviction="FIFO"
  flushInterval="60000"
  size="512"
  readOnly="true"/>

public class Blog implements Serializable {}