今日完成

1.上午又过了一遍项目的方案，问题还有很多。还是集中在限购，定时任务，回款，匹配这几个模块。

2.下午准备小课堂，讲了mybatis的常用标签和动态sql的使用

（1）常用的标签

 <!--1.根据id查找-->
   <select id="findStudentById" parameterType="Integer" resultType="lujing.pojo.Student">

    SELECT * FROM student WHERE id = #{id}
</select>

   <!--2.sql 标签与include标签 -->
   <sql id="sql_demo">name,school</sql>

   <select id="findStudentById2" parameterType="Integer" resultType="lujing.pojo.Student">

       SELECT
       <include refid="sql_demo"/>
       FROM student WHERE id = #{id}
   </select>

   <!--3. 模糊查询-->
   <select id="findStudentById3" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">

       SELECT
       *
       FROM student WHERE name LIKE "%"#{name}"%"
   </select>

   <select id="findStudentById31" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">
       SELECT
       *
       FROM student WHERE name LIKE #{name}
   </select>


   <!--4. if 标签-->
   <select id="findStudentById4" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">

       SELECT
       *
       FROM student WHERE name LIKE '%${name}%'

       <if test="address != null and address !=''">
           AND address LIKE '%${address}%'
       </if>

   </select>

   <!--bind 标签-->
   <select id="findStudentById5" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">

       SELECT
       *
       FROM student WHERE name LIKE '%${name}%'

       <if test="address != null and address !=''">
           <bind name="pattern" value="'%'+address+'%'"/>
           AND address LIKE #{pattern}
       </if>

   </select>
   <!--where 标签-->
   <select id="findStudentById6" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">

       SELECT
       *
       FROM student
       <where>
           <if test="name !=null and name != ''">
               name LIKE '%${name}%'
           </if>
           <if test="address != null and address !=''">

               AND address LIKE '%${address}%'
           </if>
       </where>

   </select>
   <!--foreach -->
   <select id="findStudentById7" parameterType="lujing.pojo.Student" resultType="lujing.pojo.Student">

       SELECT
       *
       FROM student
       <where>

           <if test="ids != null and ids !=''">

               <foreach collection="ids" item="ids2" open="(" close=")" separator="or">
                   id = #{ids2}
               </foreach>
           </if>
           <if test="name !=null and name != ''">
               AND name LIKE '%${name}%'
           </if>
           <if test="address != null and address !=''">

               AND address LIKE '%${address}%'
           </if>

       </where>
   </select>

   <!--set 标签-->
   <update id="updateStudentById" parameterType="lujing.pojo.Student">
       UPDATE student
       <set>
           <if test="name !=null and name != ''">
               name = #{name},
           </if>
           <if test="address != null and address !=''">

               address = #{address},
           </if>
       </set>
       WHERE id = #{id}
   </update>

2.学习了多线程中synchronized 关键字的使用------同步代码块

demo:

public class Ticket {
   
    
    public static void main(String[] args) {
        TicketRun ticketRun = new TicketRun();
        Thread a = new Thread(ticketRun);
        Thread b = new Thread(ticketRun);
        Thread c = new Thread(ticketRun);
        Thread d = new Thread(ticketRun);
        a.start();
        b.start();
        c.start();
        d.start();
    }
}

class TicketRun implements Runnable{
   private int num =100 ;
    @Override
    public void run() {
       
        while (true){
           
            synchronized (this){
                if(num > 0){
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    System.out.println(Thread.currentThread().getName() +"....."+ num--);
                }
            }
           
        }
    }
}

同步可以用在火车上上厕所来形容，但一个人进入之后，其他人会看到一个有人/无人的标识，其他人就不能进入。

明日计划

1.把方案做完

遇到问题

1.几个难点的解决方案

收获

1.多线程的了解。

2.mybatis 常用标签的学习