从数据库中提取多媒体信息(java,oracle)

　　用到的JAR包:ojdbc14.jar , dom4j.jar
　　
　　1.把oracle数据库中的Blob字段内容转为byte[]

//提取多媒体信息
/**
* conn - 数据库连接
* strSql - 用于查询多媒体信息的Sql语句
exp. "select multimedia from testblob where sid='test.txt'"
*/
private byte[] getMetaForOracle(Connection conn, String strSql)
throws OPException
{
Statement stmt = null;
ResultSetMetaData rset_meta = null;
int length = 0;
try {
blob = BLOB.empty_lob();
conn.setAutoCommit(false);
stmt = conn.createStatement();
rset = (ResultSet) stmt.executeQuery(strSql);
rset_meta = (ResultSetMetaData) rset.getMetaData(); // ResultSetMetaData is ojdbc14.jar
if (rset.next()) {
Blob objBlob = rset.getBlob(rset_meta.getColumnName(1));
length = (int) objBlob.length();
byte[] buffer = objBlob.getBytes(1, length);
stmt.close();
return buffer;
}
return null;
}
catch (Exception e) {
throw new OPException(e.getMessage());
}finally{
try {
if (stmt != null) {
stmt.close();
}
}
catch (SQLException ex) {
}
}
}
　　
　　2.把byte[]转为dom对象或XML字符串.代码片段

sql = " select b.multimedia from pub_blob b where id='1'" ;
byte[] xmlBlob = getMetaForOracle(conn,sql);
SAXReader reader = new SAXReader(); // dom4j.jar
ByteArrayInputStream in = new ByteArrayInputStream(xmlBlob);
InputStreamReader isr = new InputStreamReader(in,"UTF-8");
Document doc = reader.read(isr);//DocumentHelper.parseText(str);
returnXML = doc.asXML(); // dom4j.jar