反射实例
后来查了一下，原因是通过weblogic连接池取出的连接取出的blob对象是weblogic封装过的OracleThinBlob，而不是oracle.sql.BLOB。然后又看了一下OracleThinBlob的方法与oracle.sql.BLOB类似，所以采用了下面的写法，避免异常（用到的是泛型的解决方法）：
if("0".equals(type)){//上传图片
?????String update_fmp = "update web_prn_fmp set c_image_name=?,b_image=? where c_prn_fmp = '" + prnFmp+"'";
?????String query_fmp = "select b_image from web_prn_fmp where c_prn_fmp = ? FOR UPDATE" ;
?????pstmt = conn.prepareStatement(update_fmp);
?????
?????
?????pstmt.setString(1,imageName);
?????pstmt.setString(2,"0");／／初始化ｂｌｏｂ数据，否则后续的调用会出现空指针异常．
?????pstmt.executeUpdate();
?????
?????pstmt.clearParameters();
?????
?????pstmt = conn.prepareStatement(query_fmp);
?????pstmt.setString(1,prnFmp);
?????rs? = pstmt.executeQuery();
?????if(rs.next())
?????{
//??????oracle.sql.BLOB b_image = (oracle.sql.BLOB) rs.getBlob("b_image");
//??????java.io.OutputStream writer = b_image.getBinaryOutputStream();//得到对应于数据库相应blob字段的输出流
//??????BufferedOutputStream out = new BufferedOutputStream(writer);
??????//tomcat和weblogic对blob字段进行了不同的包装，需使用如下的泛型方案代码 zengshaotao 2011-03-14
??????Object obj = rs.getBlob("b_image");
??????Class clazz = obj.getClass();
??????Method method = clazz.getMethod("getBinaryOutputStream", new Class[]{});
??????OutputStream os = (OutputStream)method.invoke(obj, new Object[]{});
??????BufferedOutputStream out = new BufferedOutputStream(os);
??????
??????out.write(image);
??????rs.close();
??????//writer.close();
??????out.close();
??????conn.commit();
??????conn.setAutoCommit(true);//恢复现场
?????}else{
??????throw new Exception("没有得到与给定的单证格式代码相应的记录！");
?????}
?????
????}
