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Im getting an image from server as InputStream and then saving it to mySQL database. It works when I use `Thread.sleep(5000);`. But if I dont use it no picture is saved to the DB or only one picture and half of it or less. So I understand that the program needs time writing image to the database, but how much time? This is the question, I would like to know exactly when it finished writing image to the database and can start with the next image. Below is my code:
ResultSet rs = stmt.executeQuery(query);
while (rs.next()) {
int ID = rs.getInt(1);
String myName = rs.getString(2);
try {
String myCommand = "take picture and save /mydir/mydir2/mydir3" + myName + ".png";
telnet.sendCommand(myCommand); // Here taking a picture via telnet
// Thread.sleep(5000);// If I uncomment this line it works
String sqlCommand = "UPDATE my_table SET Picture = ? WHERE ID ='" + ID +"';";
PreparedStatement statement = conn.prepareStatement(sqlCommand);
String ftpUrl = "
ftp://"+server_IP+"/mydir/mydir2/mydir3"; + myName + ".png;type=i";
URL url = new URL(ftpUrl);
URLConnection connUrl = url.openConnection();
//Thread.sleep(5000); // If I uncomment this line, it works too.
InputStream inputStreamTelnet = connUrl.getInputStream();
statement.setBlob(1, inputStreamTelnet);
int row = statement.executeUpdate();
if (row > 0) {
System.out.println("A picture was inserted into DB.");
System.out.println("Value of row(s) : " + row);
}
} catch (Exception e) {
e.printStackTrace();
}
} // End of while
I would expect to put the waiting(sleep) after `InputStream inputStreamTelnet = connUrl.getInputStream();` but it doesnt work when I put the sleep after this line. It works only when the sleep is before. Could someone explain me why and I would like to avoid using `Thread.sleep(5000);` and instead would like to wait exact time or not wait at all which will make the program faster also there might be a case saving the picture can take more than 5 seconds or maybe saving the picture doesnt take time but opening the url connection. There are 2 sleep lines on the code when I uncomment one of them the program works(saves the images to mysql DB successfully). I also verified on the server that the images exist but in the end I dont see them in the mysql DB.
MySQL version: '5.5.37-0ubuntu0.12.04.1'
MySQL connector : mysql-connector-java-5.1.7-bin
Java version : 1.8 32bit