Convert Excel to Blob with java, save it, read it from DB and output it as a file!

When downloading a file with a web application ... The first thing that comes to mind is to set up a file server, but this method is also ... (I don't care about the size.)

** 1. Read the file **


//File reading
File uploadFile = new File("[directory]\\tmp.xlsx");
FileInputStream finstream = new FileInputStream(uploadFile);

Very simple.

** 2. Keep in DB **


//Connect to Oracle8i
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:TEST", "system", "password");
//Create statement
Statement stmt = conn.createStatement();
//SQL definition
PreparedStatement pstmt = conn.prepareStatement("INSERT INTO [Schema].test_table(file_id, deta) VALUES(0, ?)");
//Bind to statement
pstmt.setBinaryStream(1, finstream, (int) uploadFile.length());
int result = pstmt.executeUpdate();

Binary with setBinaryStream and set.

** 3. Extract binary data from DB **


//Binary data acquisition
ResultSet rset = stmt.executeQuery("select deta from [Schema].upload_file where file_id = '0'");
//Get Blob data and output to a file
Blob blob = null;
while ( {
	blob = rset.getBlob("deta");
byte[] buffer = blob.getBytes(1, (int) blob.length());

Store in byte array with getBytes

** 4. Spit to file **


//Specify output file
File file = new File("[directory]\\test001_output.xlsx");
DataOutputStream dos = new DataOutputStream(new FileOutputStream(file));
//write byte array

Simply generate and write a file.

** 5. Routine closing process **


//Close result set
//Close statement
//Close connection

//tmp file deletion

Various closes. And delete the uploaded temp file. A file is created in the specified directory.

** 6. Challenge: man_tone1: **

Last time I generated Excel using POI, I want to binaryize the file generation process and keep it in the DB with the same flow ... (I spit it out as a temp file once, read it again and make it binary)

I can't think of it for a moment, so let's try it next time!

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