详解mybatis 批量更新数据两种方法效率对比

 <!-- 这次用resultmap接收输出结果 -->
  <select id="findByName" parameterType="string" resultMap="customerMap">
    select * from t_customer where c_name like concat('%', #{name},'%') order by c_ceroNo limit 0,100
  </select>
 
 
  <!-- 批量更新第一种方法，通过接收传进来的参数list进行循环着组装sql -->
  <update id="batchUpdate" parameterType="java.util.Map">
    <!-- 接收list参数，循环着组装sql语句，注意for循环的写法
       separator=";" 代表着每次循环完，在sql后面放一个分号
       item="cus" 循环List的每条的结果集
       collection="list" list 即为 map传过来的参数key -->
    <foreach collection="list" separator=";" item="cus">
      update t_customer set
      c_name = #{cus.name},
      c_age = #{cus.age},
      c_sex = #{cus.sex},
      c_ceroNo = #{cus.ceroNo},
      c_ceroType = #{cus.ceroType}
      where id = #{cus.id}
    </foreach>
  </update>
 
  <!-- 批量更新第二种方法，通过 case when语句变相的进行批量更新 -->
  <update id="batchUpdateCaseWhen" parameterType="java.util.Map">
    update t_customer
    <trim prefix="set" suffixOverrides=",">
      <!-- 拼接case when 这是一种写法 -->
      <!--<foreach collection="list" separator="" item="cus" open="c_age = case id" close="end, ">-->
      <!--when #{cus.id} then #{cus.age}-->
      <!--</foreach>-->
 
      <!-- 拼接case when 这是另一种写法，这种写着更专业的感觉 -->
      <trim prefix="c_name =case" suffix="end,">
        <foreach collection="list" item="cus">
          <if test="cus.name!=null">
            when id=#{cus.id} then #{cus.name}
          </if>
        </foreach>
      </trim>
      <trim prefix="c_age =case" suffix="end,">
        <foreach collection="list" item="cus">
          <if test="cus.age!=null">
            when id=#{cus.id} then #{cus.age}
          </if>
        </foreach>
      </trim>
      <trim prefix="c_sex =case" suffix="end,">
        <foreach collection="list" item="cus">
          <if test="cus.sex!=null">
            when id=#{cus.id} then #{cus.sex}
          </if>
        </foreach>
      </trim>
      <trim prefix="c_ceroNo =case" suffix="end,">
        <foreach collection="list" item="cus">
          <if test="cus.ceroNo!=null">
            when id=#{cus.id} then #{cus.ceroNo}
          </if>
        </foreach>
      </trim>
      <trim prefix="c_ceroType =case" suffix="end,">
        <foreach collection="list" item="cus">
          <if test="cus.ceroType!=null">
            when id=#{cus.id} then #{cus.ceroType}
          </if>
        </foreach>
      </trim>
    </trim>
    <where>
      <foreach collection="list" separator="or" item="cus">
        id = #{cus.id}
      </foreach>
    </where>
  </update>

 List<Customer> findByName(String name);
 
  int batchUpdate(Map<String,Object> param);
 
  int batchUpdateCaseWhen(Map<String,Object> param);

 /**
   * 用于更新时，获取更新数据
   * @param name
   * @return
   */
  public List<Customer> findByName(String name) {
    SqlSession sqlSession = null;
    try {
      sqlSession = SqlsessionUtil.getSqlSession();
      return sqlSession.selectList("customer.findByName", name);
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      SqlsessionUtil.closeSession(sqlSession);
    }
    return new ArrayList<Customer>();
  }
 
 
  /**
   * 批量更新第一种方式
   * @param param
   * @return
   */
  public int batchUpdate(Map<String,Object> param) {
    return bathUpdate("customer.batchUpdate",param);
  }
 
  /**
   * 批量更新第二种方式
   * @param param
   * @return
   */
  public int batchUpdateCaseWhen(Map<String,Object> param) {
    return bathUpdate("customer.batchUpdateCaseWhen",param);
  }
 
  /**
   * 公共部分提出
   * @param statementId
   * @param param
   * @return
   */
  private int bathUpdate(String statementId,Map param){
    SqlSession sqlSession = null;
    try {
      sqlSession = SqlsessionUtil.getSqlSession();
      int key = sqlSession.update(statementId, param);
      // commit
      sqlSession.commit();
      return key;
    } catch (Exception e) {
      sqlSession.rollback();
      e.printStackTrace();
    } finally {
      SqlsessionUtil.closeSession(sqlSession);
    }
    return 0;
  }

@Test
  public void batchInsert() throws Exception {
    Map<String,Object> param = new HashMap<String,Object>();
    List<Customer> list = new ArrayList<Customer>();
    for(int i=0;i<10000;i++){
      Customer customer = new Customer();
      customer.setName("准备数据" + i);
      customer.setAge(15);
      customer.setCeroNo("111111111111"+i);
      customer.setCeroType(2);
      customer.setSex(1);
      list.add(customer);
    }
    param.put("list",list);
    Long start = System.currentTimeMillis();
    int result = customerDao.batchInsert(param);
    System.out.println("耗时 ： "+(System.currentTimeMillis() - start));
  }

  <!-- 这次用resultmap接收输出结果 -->
  <select id="findByName" parameterType="string" resultMap="customerMap">
    select * from t_customer where c_name like concat('%', #{name},'%') order by c_ceroNo limit 0,10
  </select>

  @Test
  public void batchudpate() throws Exception {
    Map<String,Object> param = new HashMap<String,Object>();
 
    param.put("list",getFindByName("准备数据","批量更新01"));
    Long start = System.currentTimeMillis();
    customerDao.batchUpdate(param);
    System.out.println("耗时 ： "+(System.currentTimeMillis() - start));
  }
 
  @Test
  public void batchudpateCaseWhen() throws Exception {
    Map<String,Object> param = new HashMap<String,Object>();
    param.put("list",getFindByName("批量更新01","准备数据"));
    Long start = System.currentTimeMillis();
    customerDao.batchUpdateCaseWhen(param);
    System.out.println("耗时 ： "+(System.currentTimeMillis() - start));
  }
 
  private List<Customer> getFindByName(String name, String change){
    List<Customer> list = customerDao.findByName(name);
    System.out.println("查询出来的条数 ： " + list.size());
    if(null != change && !"".equals(change)){
      for(Customer customer : list){
        customer.setName(change);
      }
    }
 
    return list;
  }