Download file from Mysql database

[Puk Akhimien]

Hi,

I have written the following code to download a file from a MySql database using a Servlet.The problem i have is that i havnt done it right. Can someone please point me in the right direction. Any help will be greatly appreciated. Thank you for your help.

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/
Servlet implementation class datadownload
/
public class datadownload extends HttpServlet {
private static final long serialVersionUID = 1L;

/
@see HttpServlet#HttpServlet()
/
public datadownload() {
super();
// TODO Auto-generated constructor stub
}

/
@see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub

}

/
@see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String connectionURL = "jdbc:mysql://localhost/filestore";
Connection con = null;
Statement stmt= null;
ResultSet res = null;
response.setContentType("application/octet-stream");

try{
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(connectionURL, "root", "");
stmt=con.createStatement();
res =stmt.executeQuery("select * from save_file where id='15'");
if (res .next()) {
Blob File=res .getBlob("file");
InputStream x=File.getBinaryStream();
int size=x.available();
ServletOutputStream Fileout = response.getOutputStream();
FileInputStream f = new FileInputStream("");
int nextByte = f.read();

while ( nextByte != -1 ) {
out.write(nextByte);
nextByte = f.read();
}
out.flush();
}
}




catch(Exception e){
System.out.println("Exception :"+e);
}
finally{
try{
stmt.close();
con.close();
}
catch(Exception e){
System.out.println(e);
}
}
}
} 

[Jeanne Boyarsky]

Puk Akhimien wrote:I have written the following code to download a file from a MySql database using a Servlet.The problem i have is that i havnt done it right.

What does "haven't done it right" mean? Please TellTheDetails. Did you get an error message?

[Puk Akhimien]

When I run it nothing happens. I am supposed to get a dialogue box that asks me if i want to download or open the file. This occurs when a user clicks on the download link.

[Bear Bibeault]

What have you done so far to debug this? is the servlet being invoked? is the response being sent?

[Puk Akhimien]

Well this is the code that i have so far im trying to combine the two so that when a user clicks a down load link they will get a dialogue box that asks if they want to open or save the file

[code = java ]

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.setContentType("text/html");
PrintWriter out = response.getWriter();

String connectionURL = "jdbc:mysql://localhost/filestore";
Connection con = null;
Statement stmt= null;
ResultSet res = null;
response.setContentType("application/octet-stream");

try{
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection(connectionURL, "root", "");
stmt=con.createStatement();
res =stmt.executeQuery("select * from save_file where id=1");
if (res.next()) {
Blob file=res.getBlob("file");
InputStream x=file.getBinaryStream();
int size=x.available();
byte b[]= new byte[size];
x.read(b);
}
}catch(Exception e){
System.out.println("Exception :"+e);
}
finally{
try{
stmt.close();
con.close();
}
catch(Exception e){
System.out.println(e);
}
}
}


private void downloadFile(String fileName, HttpServletRequest request, HttpServletResponse response) throws IOException {

// Set the content type to the byte-stream type (since we don't know it)
// see http://en.wikipedia.org/wiki/MIME_type for meaning of MIME type
response.setContentType("application/octet-stream");

// Set header: allows us to specify the download filename to the browser
// see http://en.wikipedia.org/wiki/List_of_HTTP_headers for header types
response.setHeader("Content-Disposition", "attachment; filename=" + new File(fileName).getName());

ServletOutputStream out = response.getOutputStream();

// Now copy requested file to the response output stream
// prefix filename with location of our files
FileInputStream f = new FileInputStream(fileName);

int nextByte = f.read();
// note: there is a faster way to do this using alternative read() methods

while ( nextByte != -1 ) {
out.write(nextByte);
nextByte = f.read();
}
out.flush();

}
}

[/code]

[Bear Bibeault]

Please UseCodeTags and please make sure that your code is properly indented. Otherwise, few people will take the time to look at it.

[Bear Bibeault]

Ans you still haven't answered my questions.