mybatis中的智能标签之一

智能标签if-where和智能标签choose（when ， otherwise）

接口：
/**
 * 智能标签if
 * @param student
 * @return
 */
public List<Student> findByIf(Student student);

/**
 * 智能标签choose
 * @param student
 * @return
 */
public List<Student> findByChoose(Student student);


xml文件（小配置）

<!--智能标签if-->
<select id="findByIf" resultType="student">
  SELECT  *from Student
      <where>
            <if test="name!=null">
                AND  name LIKE '%' #{name } '%'
            </if>
            <if test="age!=null">
                AND age>#{age}
            </if>
      </where>
</select>

<!--智能标签choose-->
<select id="findByChoose" resultType="student">
    SELECT  *from Student
    <where>
       <choose>
           <when test="name!=null">
               AND  name LIKE '%' #{name } '%'
           </when>
           <when test="age">
               AND age>#{age}
           </when>
           <otherwise>
               1=1
           </otherwise>
       </choose>
    </where>
</select>


测试类：

/**
 * 智能标签if
 */
@Test
public  void findByIf(){
    SqlSession session = MyBatisUtil.getSession();
    IStudentDAO mapper = session.getMapper(IStudentDAO.class);
      Student student=new Student();
      //student.setName("张");
      student.setAge(20);
    List<Student> list = mapper.findByIf(student);
    for (Student item:list){
        System.out.println(item.getName());
    }
    session.commit();
    session.close();
}

/**
 * 智能标签choose
 */
@Test
public  void findByChoose(){
    SqlSession session = MyBatisUtil.getSession();
    IStudentDAO mapper = session.getMapper(IStudentDAO.class);
    Student student=new Student();
    //student.setName("张");
    //student.setAge(20);
    List<Student> list = mapper.findByChoose(student);
    for (Student item:list){
        System.out.println(item.getName());
    }
    session.commit();
    session.close();
}