PB对Oracle中图片进行存取初探.doc

PB对Oracle中图片进行存取初探2006-08-28 17:51没想到用PB对Oracle进行图片的存取会如此麻烦。以前只知道PB这个开发工具有很大问题,然而这次,问题恐怕出在Oracle身上。原本想用Oracle提倡的BLOB类型处理图片,几经试验,最终还是无果而终。后来不得不用LONG RAW类型代替之。即便如此,使用LONG RAW还是出现了不明原因的错误。以下描述不够详尽,只给出个大概的解决方案,不过对于一般的图片处理已经足够了。希望我能够进一步研究出更好的解决方案来,并早日攻破BLOB类型的难关!*使用如下语句在Oracle中创建一张表person_photo:CREATE TABLE person_photo(id varchar2(8) PRIMARY KEY NOT NULL,photo LONG RAW);设置PB连接好相关数据库,在PB中建立一个窗口w_test。上面放置一个Picture控件,命名为p_1。再放置3个CommandButton控件,分别命名为cb_add,cb_modify,cb_delete。假设窗口w_test刚刚打开的时候会获得一个实例变量String is_id。-在窗口w_test的open事件中添加如下代码:Blob lb_picSELECTBLOB photoINTO :lb_picFROM person_photoWHERE id = :is_id;IF SQLCA.SQLCODE = -1 THENMessageBox(提示,初始化照片信息失败!)ROLLBACK;RETURN 0END IFIF SQLCA.SQLCODE = 0 THENthis.cb_add.enabled = FALSEEND IFIF SQLCA.SQLCODE = 100 THENthis.cb_modify.enabled = FALSEthis.cb_delete.enabled = FALSEEND IFp_1.SetPicture(lb_pic)-在按钮cb_add的clicked事件中添加如下代码:String ls_filepath,ls_filenameInteger li_numli_num = GetFileOpenName(请选择照片,ls_filepath,ls_filename,BMP,Bitmap Files (*.BMP),*.BMP)IF li_num = 0 THENRETURN 0END IFinteger li_FileNum, loops, ilong flen, bytes_read, new_posblob b, tot_b ,lb_t/ Set a wait cursorSetPointer(HourGlass!)/ Get the file length, and open the fileflen = FileLength(ls_filepath)li_FileNum = FileOpen(ls_filepath, &StreamMode!, Read!, LockRead!)/ Determine how many times to call FileReadIF flen 32765 THENIF Mod(flen, 32765) = 0 THENloops = flen/32765ELSEloops = (flen/32765) + 1END IFELSEloops = 1END IF/ Read the filenew_pos = 1FOR i = 1 to loops bytes_read = FileRead(li_FileNum, b)tot_b = tot_b + bNEXTFileClose(li_FileNum)/由于不明原因,下面这条语句有时会出错,可以改为:INSERT INTO person_photo(id)INSERT INTO person_photo(id,photo)/并把下面这句改为:VALUES(:is_id);VALUES(:is_id,EMPTY_BLOB();IF SQLCA.SQLCODE = -1 THENMessageBox(提示,插入失败!)ROLLBACK;RETURN 0END IFCOMMIT;UPDATEBLOB person_photoSET photo = :tot_bWHERE id = :is_id;IF SQLCA.SQLCODE = -1 THENMessageBox(提示,更新失败!)ROLLBACK;RETURN 0END IFCOMMIT;p_1.SetPicture(tot_b)parent.cb_add.enabled = FALSEparent.cb_modify.enabled = TRUEparent.cb_delete.enabled = TRUEMessageBox(提示,添加成功!)-在按钮cb_modify的clicked事件中添加如下代码:String ls_filepath,ls_filenameInteger li_numli_num = GetFileOpenName(请选择照片,ls_filepath,ls_filename,BMP,Bitmap Files(*.BMP),*.BMP)IF li_num = 0 THENRETURN 0END IFinteger li_FileNum, loops, ilong flen, bytes_read, new_posblob b, tot_b ,lb_t/ Set a wait cursorSetPointer(HourGlass!)/ Get the file length, and open the fileflen = FileLength(ls_filepath)li_FileNum = FileOpen(ls_filepath, &StreamMode!, Read!, LockRead!)/ Determine how many times to call FileReadIF flen 32765 THENIF Mod(flen, 32765) = 0 THENloops = flen/32765ELSEloops = (flen/32765) + 1END IFELSEloops = 1END IF/ Read the filenew_pos = 1FOR i = 1 to loops bytes_read = FileRead(li_FileNum, b)tot_b = tot_b + bNEXTFileClose(li_FileNum)UPDATEBLOB person_photoSET photo = :tot_bWHERE id = :is_id;IF SQLCA.SQLCODE = -1 THENMessageBox(提示,修改失败!)ROLLBACK;RETURN 0END IFCOMMIT;p_1.SetPicture(tot_b)MessageBox(提示,修改失败!)-在按钮cb_delete的clicked事件中添加如下代码:IF MessageBox(提示,确定要删除吗?,Question!,YesNo!) = 2 THENRETURN 0END IFDELETE FROM person_photoWHERE id = :is_id;IF SQLCA.SQLCODE = -1 T