如何使用PL/SQL读取数据库中的BLOB对象

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使用PL/SQL从数据库中读取BLOB对象:

1.首先，确认现有对象

SQL> col fdesc for a30
SQL> select fid,fname,fdesc from eygle_blob;

    FID FNAME                        FDESC
------------------------ ------------------------------
   1 ShaoLin.jpg                少林寺-康熙手书
   2 DaoYing.jpg                     倒映

2.创建存储Directory

SQL> connect / as sysdba
Connected.
SQL> create or replace directory BLOBDIR as 'D:oradataPic';

Directory created.

SQL>
SQL> grant read,write on directory BLOBDIR to eygle;

Grant succeeded.

SQL>

3.创建存储过程

以下是代码片段：
SQL> connect eygle/eygle
Connected.
SQL>
SQL> CREATE OR REPLACE PROCEDURE eygle_dump_blob (piname varchar2,poname varchar2) IS
  2    l_file      UTL_FILE.FILE_TYPE;
  3    l_buffer    RAW(32767);
  4    l_amount    BINARY_INTEGER := 32767;
  5    l_pos       INTEGER := 1;
  6    l_blob      BLOB;
  7    l_blob_len  INTEGER;
  8  BEGIN
  9    SELECT FPIC
10    INTO      l_blob
11    FROM      eygle_blob
12    WHERE  FNAME = piname;
13
14    l_blob_len := DBMS_LOB.GETLENGTH(l_blob);
15    l_file := UTL_FILE.FOPEN('BLOBDIR',poname,'wb', 32767);
16
17    WHILE l_pos < l_blob_len LOOP
18      DBMS_LOB.READ (l_blob, l_amount, l_pos, l_buffer);
19      UTL_FILE.PUT_RAW(l_file, l_buffer, TRUE);
20      l_pos := l_pos + l_amount;
21    END LOOP;
22
23    UTL_FILE.FCLOSE(l_file);
24
25  EXCEPTION
26    WHEN OTHERS THEN
27      IF UTL_FILE.IS_OPEN(l_file) THEN
28        UTL_FILE.FCLOSE(l_file);
29      END IF;
30      RAISE;
31  END;
32  /

Procedure created.

4.最后取出数据

以下是代码片段：
SQL> host ls -l d:oradataPic
total 7618
-rwxrwxrwa   1 gqgai           None            2131553 Apr 19 10:12 DaoYing.jpg
-rwxrwxrwa   1 gqgai           None            1768198 Apr 19 10:12 ShaoLin.jpg

SQL> exec eygle_dump_blob('ShaoLin.jpg','01.jpg')

PL/SQL procedure successfully completed.

SQL> host ls -l d:oradataPic
total 11072
-rwxrwxrwa   1 Administrators  SYSTEM          1768198 Apr 26 07:16 01.jpg
-rwxrwxrwa   1 gqgai           None            2131553 Apr 19 10:12 DaoYing.jpg
-rwxrwxrwa   1 gqgai           None            1768198 Apr 19 10:12 ShaoLin.jpg

SQL>
SQL> exec eygle_dump_blob('DaoYing.jpg','02.jpg')

PL/SQL procedure successfully completed.

SQL> host ls -l d:oradataPic
total 15236
-rwxrwxrwa   1 Administrators  SYSTEM          1768198 Apr 26 07:16 01.jpg
-rwxrwxrwa   1 Administrators  SYSTEM          2131553 Apr 26 07:19 02.jpg
-rwxrwxrwa   1 gqgai           None            2131553 Apr 19 10:12 DaoYing.jpg
-rwxrwxrwa