Mybatis批量操作

Mybatis批量操作有两种方式：
  (1) 在mapper.xml文件动态生成多条sql语句，生成的sql语句类似如下：
      <insert id="insert" parameterType="sdc.mybatis.test.Student">
          <!-- WARNING - @mbggenerated This element is automatically generated by
               MyBatis Generator, do not modify. This element was generated on Mon May 09
               11:09:37 CST 2011. -->
          insert into student (id, name, sex,
          address, telephone, t_id
          )
          values (#{id,jdbcType=INTEGER}, #{name,jdbcType=VARCHAR},
          #{sex,jdbcType=VARCHAR},
          #{address,jdbcType=VARCHAR}, #{telephone,jdbcType=VARCHAR}, #{tId,jdbcType=INTEGER}
          )
       </insert>   
      
  (2) 使用sqlSessionFactory.openSession(ExecutorType.BATCH, false)开启一个批量操作的session，后续使用从session中获取的mapper对象进行数据库操作时，自动会采用JDBC的批量操作，但前提是:必须连续调用某一个mapper对象的方法，否则会产生多个PrepareStatement对象。数量过大后会导致“超出打开游标的最大数”异常
 
    Mybatis代码举例：
    结论：batchInserts1方法只使用两个Cursor而batchInserts2会使用6000个Cursour。区别在于方法2中对mapper的方法进行了交叉调用
    代码：
     public void batchInserts1() {
        String clientId = "102101000004";

        SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH, false);
        try {
            DeviceDataMapper deviceDataMapper = sqlSession.getMapper(DeviceDataMapper.class);
            RfGprsTagDataMapper tagDataMapper = sqlSession.getMapper(RfGprsTagDataMapper.class);
            for (int i = 0; i < 3000; i++) {
                DeviceData deviceData = new DeviceData();
                deviceData.setClientId(clientId);
                deviceData.setDeviceId("6");
                deviceData.setRecId(BigDecimal.valueOf(UIDUtils.getInstance().generateUID(UIDTypeCode.DEVICEDATA).longValue()));
                deviceData.setCreatedBy(4L);
                deviceDataMapper.insert(deviceData);
            }
            for (int i = 0; i < 3000; i++) {
                RfGprsTagData tagData = new RfGprsTagData();
                tagData.setClientId(clientId);
                tagData.setTagId("F01000000000000000000194");
                tagData.setRecId(BigDecimal.valueOf(UIDUtils.getInstance().generateUID(UIDTypeCode.RFGPRSTAGDATA)
                        .longValue()));
                tagData.setCreatedBy(4L);
                tagDataMapper.insert(tagData);
            }
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            sqlSession.close();
        }
    }

    public void batchInserts2() {
        String clientId = "102101000004";

        SqlSession sqlSession = sqlSessionFactory.openSession(ExecutorType.BATCH, false);
        try {
            DeviceDataMapper deviceDataMapper = sqlSession.getMapper(DeviceDataMapper.class);
            RfGprsTagDataMapper tagDataMapper = sqlSession.getMapper(RfGprsTagDataMapper.class);
            for (int i = 0; i < 3000; i++) {
                DeviceData deviceData = new DeviceData();
                deviceData.setClientId(clientId);
                deviceData.setDeviceId("6");
                deviceData.setRecId(BigDecimal.valueOf(UIDUtils.getInstance().generateUID(UIDTypeCode.DEVICEDATA).longValue()));
                deviceData.setCreatedBy(4L);
                deviceDataMapper.insert(deviceData);
               
                RfGprsTagData tagData = new RfGprsTagData();
                tagData.setClientId(clientId);
                tagData.setTagId("F01000000000000000000194");
                tagData.setRecId(BigDecimal.valueOf(UIDUtils.getInstance().generateUID(UIDTypeCode.RFGPRSTAGDATA).longValue()));
                tagData.setCreatedBy(4L);
                tagDataMapper.insert(tagData);
            }
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            sqlSession.rollback();
        } finally {
            sqlSession.close();
        }
    }


PS: 游标说明
         1．对于oracle中Cursor分隐式和显式的两种，具体的定义可以自行去网上查下，Cursor数量在oracle里有限制的，而且也有一定量的内存消耗，同时打开的数量越大，内存的消耗肯定越大。
         2. JDBC里对Cursor打开和关闭对应如下：
            a. 只要创建一个statement对象就会打开一个Cursor
            b. 调用statement对象的close方法将会关闭相应的Cursor；
            c. 在执行Connection对象的close方法时也会去关闭该Connection对象所打开的所有Cursor（在忘执行statement对象的close方法时产生的）