問題描述
從數據庫中讀取 zip 存檔 (Reading zip archive from database)
I have a zip file which I store in the database as a blob field. When I want to download it from it the zip file is corrupted. I can open it only from 7zip. The file is ok when I try to open it before upload it in the DB and when is in the DB. When I retrieve the file from the database as a blob I get this error when try to unzip it on unix
Archive: test.zip
End‑of‑central‑directory signature not found. Either this file is not
a zipfile, or it constitutes one disk of a multi‑part archive. In the
latter case the central directory and zipfile comment will be found on
the last disk(s) of this archive.
unzip: cannot find zipfile directory in one of test.zip or
test.zip.zip, and cannot find test.zip.ZIP, period.
Here is the code when I retrieve the zip from the database :
public oracle.sql.BLOB GetBlob(Connection myConn,
CallableStatement cstmt) throws Exception {
String strSql = null;
BLOB tempBlob = null;
try {
strSql = .... // Here is the sql procedure which I called to retrieve the blobl field.
cstmt = myConn.prepareCall(strSql);
cstmt.registerOutParameter(1, OracleTypes.BLOB);
cstmt.setLong(2, request_id);
cstmt.execute();
tempBlob = (oracle.sql.BLOB)cstmt.getObject(1);
int bufsize = tempBlob.getBufferSize();
} catch (Exception e) {
e.printStackTrace();
throw e;
}
return tempBlob;
Here is the reading :
oracle.sql.BLOB tempBlob = null;
Connection myConn = null;
CallableStatement cstmt = null;
try {
myConn = DBHelper.getConnection();
if (null == myConn)
throw new SQLException();
tempBlob = GetBlob(myConn, cstmt);
int bufsize = tempBlob.getBufferSize();
InputStream in = tempBlob.getBinaryStream();
int length = 0;
byte buf[] = new byte[bufsize];
while ((in != null) && ((length = in.read(buf)) != ‑1)) {
out.write(buf, 0, length);
}
in.close();
// out.flush();
// out.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (null != myConn) {
try {
myConn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
if (cstmt != null) {
try {
cstmt.close();
} catch (SQLException e) {
}
}
}
Could somebody help me.
Thanks in advance.
‑‑‑‑‑
參考解法
方法 1:
Compare the files before and after. The difference should give you some hint what is going wrong.
Possible culprits are:
- Missing bytes at the end
- converted bytes
- messed up order of bytes
I'd expect looking at the first 10, the last 10 and the total number of bytes should be sufficient to give you a good idea what is going on.
(by Jordan Borisov、Jens Schauder)