Upload
It is similar to the previous article, but the text format is inserted first. This is a small use case for blob. Now upload the attachment code:
1 // Add a file --------- save the file to the database
2 Public void attach (string filename, string FN, string username, String title)
3 {users. class1 u = new users. class1 (); // obtain the user ID
4 int uid = U. getuserid (username );
5 papers. Papers P = new papers ();
6 int paper_id = P. getpaperid (title, UID); // obtain the paper ID.
7 string SQL = "Update paper_table set attach =: AA, attachfilename =: BB where id = '" + paper_id + "'";
8 oraclecommand cmd = new oraclecommand (SQL, Conn );
9 conn. open ();
10 filestream FS = file. openread (filename );
11 byte [] B = new byte [fs. Length];
12 FS. Read (B, 0, B. Length );
13 FS. Close ();
14
15 cmd. Parameters. Add ("AA", system. Data. oracleclient. oracletype. bfile, B. Length). value = B;
16 cmd. Parameters. Add ("BB", system. Data. oracleclient. oracletype. varchar). value = FN;
17 cmd. executenonquery ();
18 conn. Close ();
19}
Download
First, convert the downloaded binary data to the format previously stored in the database. That is, the file extension must be saved when the file is saved.
The converted file is stored in a temporary folder, and then you can directly download response. Redirect.
1 // download the file-collected on the internet is just an annotation-the following is for the Oracle database, the same as for SQL Server
2 Public String download (string PID, string path)
3 {
4
5 filestream objfs;
6
7 binarywriter objbw;
8
9 int buffersize = 260000; // This is the buffer size. The value is too small. If the value is smaller than the downloaded file size, an error occurs.
10
11 byte [] outbyte = new byte [buffersize];
12
13 long retval;
14
15 long startindex = 0;
16
17 string filename = "";
18
19 string SQL = "select * From paper_table where id = '" + PID + "'"; // obtain from database
20 oraclecommand cmd = new oraclecommand (SQL, Conn );
21 conn. open ();
22 oracledatareader DR = cmd. executereader (commandbehavior. sequentialaccess );
23 dr. Read ();
24
25 filename = Dr ["attachfilename"]. tostring (); // file name
26 string tempfilename = filename;
27 filename = path + filename;
28 objfs = new filestream (filename, filemode. openorcreate, fileaccess. Write );
29
30 objbw = new binarywriter (objfs );
31
32 startindex = 0;
33
34 retval = dr. getbytes (8, startindex, outbyte, 0, buffersize );
35
36 while (retval = buffersize)
37 {
38 objbw. Write (outbyte );
39
40 objbw. Flush ();
41
42 startindex + = buffersize;
43
44 retval = dr. getbytes (8, startindex, outbyte, 0, buffersize );
45}
46
47 objbw. Write (outbyte, 0, (INT) retval-1 );
48
49 objbw. Flush ();
50
51 objbw. Close ();
52
53 objfs. Close ();
54
55 dr. Close ();
56
57 conn. Close ();
58 return tempfilename;
59
60
61
62
63
64
65
66}
67
