UTL_COMPRESS Zipping Multiple BLOBs

Question

Hey everyone, I'm having trouble figuring out how to use UTL_COMPRESS.
What I want to do is take several BLOBs from one table, and put them into one zip file. Can anyone show me an example of where this is done?
Here is some sample code of what I have so far:
My table:
CREATE TABLE  "FILES"
   (     "FILE_ID" NUMBER,
     "FILE_TYPE" NUMBER,
     "FILENAME" VARCHAR2(1000),
     "DATE_ADDED" DATE,
     "ADDED_BY" VARCHAR2(255),
     "FILE_BLOB" BLOB,
/Some sample code:
DECLARE
  b_dl_file1 BLOB;
  b_dl_file2 BLOB;
  b_dl_file3 BLOB;
  b_compressed_file BLOB;
BEGIN
select FILE_BLOB
into b_dl_file1
from FILES
where FILE_ID = 64;
select FILE_BLOB
into b_dl_file2
from FILES
where FILE_ID = 65;
select FILE_BLOB
into b_dl_file3
from FILES
where FILE_ID = 66;
b_compressed_file := UTL_COMPRESS.LZ_COMPRESS(b_dl_file1);
END;So what I've posted works fine, it compresses a single file. What I want is to take all three of those blobs (for example) and add them to one zip file. I've looked into using UTL_COMPRESS.LZ_COMPRESS_ADD, but as far as I can see, that only takes RAW data. Will I have to break my BLOBs into RAW strings and then compress those? Will that even work?
Any help would be appreciated!

Answer 1

Wow! Thanks! That's exactly what I'm looking for. I'm having some trouble getting this code to run though, I'm recieving the following error:
"ORA-06502: PL/SQL: numeric or value error: invalid LOB locator specified: ORA-22275 "
I've been debugging and it looks like its coming from the add1file procedure.
I modified the code a bit to make it into a package:
CREATE OR REPLACE PACKAGE zip_blobs AS
  /*Package written by Anton Scheffer, used with permission*/
  PROCEDURE add1file(p_zipped_blob in out blob, p_name in varchar2, p_content in blob);
  PROCEDURE finish_zip(p_zipped_blob in out blob);
  PROCEDURE save_zip(p_zipped_blob in blob, p_dir in varchar2, p_filename in varchar2);
END zip_blobs;
CREATE OR REPLACE PACKAGE BODY zip_blobs AS
  function little_endian( p_big in number, p_bytes in pls_integer := 4 )
  return raw
  is
  begin
    return utl_raw.substr( utl_raw.cast_from_binary_integer( p_big, utl_raw.little_endian ), 1, p_bytes );
  end;
  procedure add1file
    ( p_zipped_blob in out blob
    , p_name in varchar2
    , p_content in blob
  is
    t_now date;
    t_blob blob;
    t_clen integer;
  begin
    t_now := sysdate;
    t_blob := utl_compress.lz_compress( p_content );
    t_clen := dbms_lob.getlength( t_blob );
    if p_zipped_blob is null
    then
      dbms_lob.createtemporary( p_zipped_blob, true );
    end if;
    dbms_lob.append( p_zipped_blob
                   , utl_raw.concat( hextoraw( '504B0304' ) -- Local file header signature
                                   , hextoraw( '1400' )     -- version 2.0
                                   , hextoraw( '0000' )     -- no General purpose bits
                                   , hextoraw( '0800' )     -- deflate
                                   , little_endian( to_number( to_char( t_now, 'ss' ) ) / 2
                                                  + to_number( to_char( t_now, 'mi' ) ) * 32
                                                  + to_number( to_char( t_now, 'hh24' ) ) * 2048
                                                  , 2
                                                  ) -- File last modification time
                                   , little_endian( to_number( to_char( t_now, 'dd' ) )
                                                  + to_number( to_char( t_now, 'mm' ) ) * 32
                                                  + ( to_number( to_char( t_now, 'yyyy' ) ) - 1980 ) * 512
                                                  , 2
                                                  ) -- File last modification date
                                   , dbms_lob.substr( t_blob, 4, t_clen - 7 )         -- CRC-32
                                   , little_endian( t_clen - 18 )                     -- compressed size
                                   , little_endian( dbms_lob.getlength( p_content ) ) -- uncompressed size
                                   , little_endian( length( p_name ), 2 )             -- File name length
                                   , hextoraw( '0000' )                               -- Extra field length
                                   , utl_raw.cast_to_raw( p_name )                    -- File name
    dbms_lob.append( p_zipped_blob, dbms_lob.substr( t_blob, t_clen - 18, 11 ) );     -- compressed content
    dbms_lob.freetemporary( t_blob );
  end;
  procedure finish_zip( p_zipped_blob in out blob )
  is
    t_cnt pls_integer := 0;
    t_offs integer;
    t_offs_dir_header integer;
    t_offs_end_header integer;
    t_comment raw(32767) := utl_raw.cast_to_raw( 'Implementation by Anton Scheffer' );
  begin
    t_offs_dir_header := dbms_lob.getlength( p_zipped_blob );
    t_offs := dbms_lob.instr( p_zipped_blob, hextoraw( '504B0304' ), 1 );
    while t_offs > 0
    loop
      t_cnt := t_cnt + 1;
      dbms_lob.append( p_zipped_blob
                     , utl_raw.concat( hextoraw( '504B0102' )      -- Central directory file header signature
                                     , hextoraw( '1400' )          -- version 2.0
                                     , dbms_lob.substr( p_zipped_blob, 26, t_offs + 4 )
                                     , hextoraw( '0000' )          -- File comment length
                                     , hextoraw( '0000' )          -- Disk number where file starts
                                     , hextoraw( '0100' )          -- Internal file attributes
                                     , hextoraw( '2000B681' )      -- External file attributes
                                     , little_endian( t_offs - 1 ) -- Relative offset of local file header
                                     , dbms_lob.substr( p_zipped_blob
                                                      , utl_raw.cast_to_binary_integer( dbms_lob.substr( p_zipped_blob, 2, t_offs + 26 ), utl_raw.little_endian )
                                                      , t_offs + 30
                                                      )            -- File name
      t_offs := dbms_lob.instr( p_zipped_blob, hextoraw( '504B0304' ), t_offs + 32 );
    end loop;
    t_offs_end_header := dbms_lob.getlength( p_zipped_blob );
    dbms_lob.append( p_zipped_blob
                   , utl_raw.concat( hextoraw( '504B0506' )                                    -- End of central directory signature
                                   , hextoraw( '0000' )                                        -- Number of this disk
                                   , hextoraw( '0000' )                                        -- Disk where central directory starts
                                   , little_endian( t_cnt, 2 )                                 -- Number of central directory records on this disk
                                   , little_endian( t_cnt, 2 )                                 -- Total number of central directory records
                                   , little_endian( t_offs_end_header - t_offs_dir_header )    -- Size of central directory
                                   , little_endian( t_offs_dir_header )                        -- Relative offset of local file header
                                   , little_endian( nvl( utl_raw.length( t_comment ), 0 ), 2 ) -- ZIP file comment length
                                   , t_comment
  end;
  procedure save_zip
    ( p_zipped_blob in blob
    , p_dir in varchar2
    , p_filename in varchar2
  is
    t_fh utl_file.file_type;
    t_len pls_integer := 32767;
  begin
    t_fh := utl_file.fopen( p_dir, p_filename, 'wb' );
    for i in 0 .. trunc( ( dbms_lob.getlength( p_zipped_blob ) - 1 ) / t_len )
    loop
      utl_file.put_raw( t_fh, dbms_lob.substr( p_zipped_blob, t_len, i * t_len + 1 ) );
    end loop;
    utl_file.fclose( t_fh );
  end;
END zip_blobs;My code:
DECLARE
  b_dl_file1 BLOB;
  b_dl_file2 BLOB;
  b_dl_file3 BLOB;
  b_zipped_blob BLOB;
BEGIN
  select FILE_BLOB
  into b_dl_file1
  from FILES
  where FILE_ID = 64;
  select FILE_BLOB
  into b_dl_file2
  from FILES
  where FILE_ID = 65;
  select FILE_BLOB
  into b_dl_file3
  from FILES
  where FILE_ID = 66;
  zip_blobs.add1file(b_zipped_blob, 'test1.bin', b_dl_file1);
  zip_blobs.add1file(b_zipped_blob, 'test2.bin', b_dl_file2);
  zip_blobs.add1file(b_zipped_blob, 'test3.bin', b_dl_file3);
  zip_blobs.finish_zip(b_zipped_blob);
  insert into compressed_files(compressed_blob) values(b_zipped_blob);
END;So I'm inserting it into a table, but even when I use save_zip, I get the same error. I tried playing around with freeing p_zipped_blob and not freeing t_blob, but it didn't seem to work, and I'm not seeing where else it could be going wrong. Any more help would be awesome!
Thanks!