iBATIS操作Blob与Clob浅析

iBATIS操作Blob与Clob浅析

http://developer.51cto.com/art/200907/136668.htm


spring 中已经提供了很好的实现，所以这又省去了很多的功夫，接下来看看 iBATIS是如何支持 Clob和blob的。

iBATIS提供了TypeHandler接口，用于处理数据类型，基本的实现类为BaseTypeHandler

在spring 中，提供了AbstractLobTypeHandler作为基础类，并且提供了相应的模版方法，所有的工作由LobHandler处理。

BlobByteArrayTypeHandler 主要用于处理blob类型数据，使用byte[]来映射相应的Blob

ClobStringTypeHandler 用于处理Clob类型数据，使用字符串来映射Clob

有一点需要注意的是，AbstractLobTypeHandler中实现了事务支持，需要用来释放相应的资源，所以一定需要在事务环境中进行。

下面是一个简单的例子：

public class Food {
private String content;

private String id;

private byte[] image;

private String name;
    ...
}

xml如下：说明一下，在resultMap中可以通过typeHandler来指定具体的handler.在inline变量中，可以通过handler来定义相应的typeHandler

﹤sqlMap namespace="Food"﹥

   ﹤typeAlias alias="Food" type="org.esoft.hdb.bo.Food"/﹥
   ﹤resultMap id="foodResult" class="Food"﹥
  ﹤result property="id" column="C_ID"/﹥
  ﹤result property="name" column="C_NAME"/﹥
  ﹤result property="content" column="C_content"
 typeHandler="org.springframework.orm.ibatis.support.ClobStringTypeHandler"/﹥
  ﹤result property="image" column="C_image"
 typeHandler="org.springframework.orm.ibatis.support.BlobByteArrayTypeHandler"/﹥
   ﹤/resultMap﹥
   ﹤sql id="foodFragment"﹥select C_ID,C_NAME,C_CONTENT,C_IMAGE from T_FOOD﹤/sql﹥
  ﹤select id="getAll" resultMap="foodResult"﹥
  ﹤include refid="foodFragment"/﹥
   ﹤/select﹥
   ﹤select id="selectById" parameterClass="string" resultMap="foodResult"﹥
  ﹤include refid="foodFragment"/﹥ where C_ID=#id#﹤/select﹥

   ﹤insert id="insert" parameterClass="Food"﹥ insert into T_FOOD ( C_ID,
  C_NAME,C_CONTENT, C_IMAGE) values ( #id#,
  #name#,#content,handler=org.springframework.orm.ibatis.support.ClobStringTypeHandler#,
  #image,handler=org.springframework.orm.ibatis.support.BlobByteArrayTypeHandler#)
  ﹤/insert﹥

   ﹤update id="update" parameterClass="Food"﹥ update T_FOOD set C_NAME = #name#,
  C_CONTENT =
  #content,handler=org.springframework.orm.ibatis.support.ClobStringTypeHandler#,
  C_IMAGE =
  #image,handler=org.springframework.orm.ibatis.support.BlobByteArrayTypeHandler#
  where C_ID = #id# ﹤/update﹥

   ﹤delete id="deleteById" parameterClass="string"﹥ delete from T_FOOD where C_ID = #id#
  ﹤/delete﹥

﹤/sqlMap﹥


public interface FoodService {


void save(Food food);
Food get(String id);
/**
* @param food
*/
void update(Food food);
}

public class FoodServiceImpl implements FoodService {
private FoodDAO foodDAO;

private DaoCreator creator;

public void setCreator(DaoCreator creator) {
    this.creator = creator;
}

protected FoodDAO getFoodDAO() {
    if (foodDAO == null) {
   foodDAO = (FoodDAO) creator.createDao(FoodDAO.class, Food.class);
    }
    return foodDAO;
}

public Food get(String id) {
    return getFoodDAO().get(id);
}
public void save(Food food) {
    getFoodDAO().save(food);
}
public void update(Food food) {
    getFoodDAO().update(food);
}

}

spring xml 配置：

。。。
 ﹤bean id="lobHandler"
  class="org.springframework.jdbc.support.lob.DefaultLobHandler"/﹥

   ﹤bean id="transactionManager"
  class="org.springframework.jdbc.datasource.DataSourceTransactionManager"﹥
  ﹤property name="dataSource" ref="dataSource"/﹥
   ﹤/bean﹥

   ﹤bean id="sqlMapClient"
  class="org.springframework.orm.ibatis.SqlMapClientFactoryBean"﹥
  ﹤property name="dataSource" ref="dataSource"/﹥
  ﹤property name="configLocation"﹥
 ﹤value﹥SqlMapConfig.xml﹤/value﹥
  ﹤/property﹥
  ﹤property name="lobHandler" ref="lobHandler"/﹥
   ﹤/bean﹥

   ﹤bean id="daoCreate" class="org.esoft.hdb.ibatis.IbatisDaoCreator"﹥
  ﹤property name="sqlMapClient" ref="sqlMapClient"/﹥
   ﹤/bean﹥

   ﹤bean id="foodService" class="org.esoft.hdb.service.FoodServiceImpl"﹥
  ﹤property name="creator" ref="daoCreate"/﹥
   ﹤/bean﹥


   ﹤aop:config﹥
  ﹤aop:pointcut id="foodServiceMethods"
 expression="execution(* org.esoft.hdb.service.FoodService.*(..))"/﹥
  ﹤aop:advisor advice-ref="txAdvice" pointcut-ref="foodServiceMethods"/﹥
   ﹤/aop:config﹥
   ﹤tx:advice id="txAdvice" transaction-manager="transactionManager"﹥
  ﹤tx:attributes﹥
 ﹤tx:method name="*" propagation="REQUIRED"/﹥
  ﹤/tx:attributes﹥
   ﹤/tx:advice﹥

简单的测试：

save :
    Food food = new Food();
    food.setPk("1");
    food.setName("food1");
    BufferedInputStream in = new BufferedInputStream(getClass()
  .getResourceAsStream("/1.gif"));
    byte[] b = FileCopyUtils.copyToByteArray(in);
    food.setImage(b);
  in = new BufferedInputStream(getClass().getResourceAsStream(
  "/hibernate.cfg.xml"));
    b = FileCopyUtils.copyToByteArray(in);
    food.setContent(new String(b));
    foodService.save(food);
update:
Food food = foodService.get("1");
    BufferedInputStream in = new BufferedInputStream(getClass()
  .getResourceAsStream("/jdbc.properties"));
    byte[] b = FileCopyUtils.copyToByteArray(in);
    food.setContent(new String(b));
    foodService.update(food);
    food = foodService.get("1");
    assertNotNull(food.getImage());