用jdbcTempate調用存儲過程,處理BLOB/CLOB小記
1、利用spring的jdbcTemplate調用存儲過程
假如我們有P_GET_TOPIC_NUM這一個存儲過程,有兩個參數,第一個參數userId是傳進去的,第二個參數是傳出來的,舉例如下:
Java代碼
public int getUserTopicNum(final int userId) {
String sql = "{call P_GET_TOPIC_NUM(?,?)}";
//使用? Object execute(String callString, CallableStatementCallback action)接口
Object obj = getJdbcTemplate().execute(sql,new CallableStatementCallback(){
public Object doInCallableStatement(CallableStatement cs) throws SQLException, DataAccessException {
cs.setInt(1,userId);
cs.registerOutParameter(2, Types.INTEGER);
cs.execute();
return new Integer(cs.getInt(2));
}
});
return ((Integer)obj).intValue();
}
2、spring定義了一個以統一的方式操作各種數據庫的Lob類型數據的LobCreator(保存的時候用),同時提供了一個LobHandler爲操作二進制字段和大文本字段提供統一接口訪問。
舉例，例子裏面的t_post表中post_text字段是CLOB類型,而post_attach是BLOG類型：
Java代碼
public class PostJdbcDao extends JdbcDaoSupport implements PostDao {
private LobHandler lobHandler;
private DataFieldMaxValueIncrementer incre;
public LobHandler getLobHandler() {
return lobHandler;
}
public void setLobHandler(LobHandler lobHandler) {
this.lobHandler = lobHandler;
}
public void addPost(final Post post) {
String sql = " INSERT INTO t_post(post_id,user_id,post_text,post_attach)"
+ " VALUES(?,?,?,?)";
getJdbcTemplate().execute(
sql,
new AbstractLobCreatingPreparedStatementCallback(
this.lobHandler) {
protected void setValues(PreparedStatement ps,
LobCreator lobCreator) throws SQLException {
ps.setInt(1, incre.nextIntValue());
ps.setInt(2, post.getUserId());
lobCreator.setClobAsString(ps, 3, post.getPostText());
lobCreator.setBlobAsBytes(ps, 4, post.getPostAttach());
}
});
}
}
設置相對應的配置文件(Oracle 9i版本),Oracle的數據庫最喜歡搞搞特別的東西啦：
Java代碼
<bean id="nativeJdbcExtractor"
class="org.springframework.jdbc.support.nativejdbc.CommonsDbcpNativeJdbcExtractor"
lazy-init="true" />
<bean id="oracleLobHandler"
class="org.springframework.jdbc.support.lob.OracleLobHandler"
lazy-init="true">
<property name="nativeJdbcExtractor" ref="nativeJdbcExtractor" />
</bean>
<bean id="dao" abstract="true">
<property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>
<bean id="postDao" parent="dao"
class="com.baobaotao.dao.jdbc.PostJdbcDao">
<property name="lobHandler" ref="oracleLobHandler" />
</bean>
Oracle 10g或其他數據庫如下設置：
Java代碼
<bean id="defaultLobHandler"
class="org.springframework.jdbc.support.lob.DefaultLobHandler"
lazy-init="true" />
<bean id="dao" abstract="true">
<property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>
<bean id="postDao" parent="dao"
class="com.baobaotao.dao.jdbc.PostJdbcDao">
<property name="lobHandler" ref="defaultLobHandler" />
</bean>
讀取BLOB/CLOB塊,舉例：
Java代碼
public List getAttachs(final int userId){
String sql = "SELECT post_id,post_attach FROM t_post where user_id =? and post_attach is not null";
return getJdbcTemplate().query(
sql,new Object[] {userId},
new RowMapper() {
public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
Post post = new Post();
int postId = rs.getInt(1);
byte[] attach = lobHandler.getBlobAsBytes(rs, 2);
post.setPostId(postId);
post.setPostAttach(attach);
return post;
}
});
}
注：代碼均來自<<精通spring2.x企業應用開發詳解>>