java - 从数据库读取 zip 存档

Question

我有一个 zip 文件，我将其作为 blob 字段存储在数据库中。当我想从中下载它时，zip 文件已损坏。我只能从 7zip 打开它。当我尝试在将其上传到数据库之前以及在数据库中时打开该文件时，该文件正常。当我从数据库中以 blob 形式检索文件时，尝试在 unix 上解压缩该文件时出现此错误

    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.

这是我从数据库检索 zip 时的代码:

        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;

这是阅读内容:

                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) {
                    }
                }

            }

有人可以帮我吗

提前致谢。

Answer 1

比较之前和之后的文件。这种差异应该会给您一些提示，说明哪里出了问题。

可能的罪魁祸首是:

• 末尾缺少字节
• 转换后的字节
• 字节顺序困惑

我希望查看前 10 个、后 10 个字节和总字节数应该足以让您清楚地了解发生了什么。