Download any file from Database

package com.edu.main;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;


public class DownloadFileFromDB {

public static void main(String[] args) {

final String host = "jdbc:oracle:thin:@<host>:1521:<service_name>";
final String user = "username";
final String pass = "*******";
String SQL = "SELECT <COLUMN> FROM <TABLE> WHERE <COLUMN>=?";

Connection conn = null;
PreparedStatement smt = null;
InputStream input = null;
FileOutputStream output = null;
ResultSet rs = null;

try {

Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection(host, user, pass);
System.out.println("DB Connection successful..");

smt = conn.prepareStatement(SQL);
smt.setString(1, "<VALUE_TO_BE_REPLACED_WITH_?>");
rs = smt.executeQuery();

output = new FileOutputStream(new File("C:\\Users\\bismaya\\Desktop\\<FILENAME>.<EXT>"));

while (rs.next()) {
input = rs.getBinaryStream("<COLUMN_OF_FILE_IN_DB>");
int r = 0;
while ((data = input.read()) != -1) {
output.write(data);
}
}
System.out.println("Success...");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
System.err.println("DB Connection failed!");
e.printStackTrace();
} catch (FileNotFoundException e) {
System.err.println("File not found in provided location!");
e.printStackTrace();
} catch (IOException e) {
System.err.println("Error while writing to file!");
e.printStackTrace();
} finally {
if (rs != null) {
try {
input.close();
output.flush();
output.close();
smt.close();
conn.close();
} catch (SQLException e) {
System.err.println("Error while closing the connecton!");
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

}

Apache httpd load balancer setup

Install httpd as service by following  http://httpd.apache.org/docs/2.4/install.html 

sudo yum install httpd
sudo systemctl enable httpd
sudo systemctl start httpd

1) Edit /etc/httpd/conf/httpd.conf and change the Listen port to configure the Load balancer port. By default port will be 80.

2) Add a file lb.conf under /etc/httpd/conf.d to configure members to be redirected. httpd service will load all *.conf files present under /etc/httpd/conf.d folder.

3) lb.conf content example as below.

ProxyRequests off
<Proxy balancer://Testbalancer>
BalancerMember <URL1>
BalancerMember <URL2>
BalancerMember <URL3>
ProxySet lbmethod=byrequests Or ProxySet lbmethod=bybusyness Or lbmethod=bytraffic
</Proxy>
<Location /balancer-manager>
SetHandler balancer-manager
</Location>
ProxyPass /balancer-manager !
ProxyPass / balancer://Testbalancer/ connectiontimeout=30 timeout=60


This will redirect all request http://<host>/ to either <URL1> or <URL2> or <URL3>

4) You can configure ProxyPass to redirect in case some specific string comes after the URL.

    ProxyPass "/test" balancer://Testbalancer/ connectiontimeout=30 timeout=60

    ProxyPassMatch "^/(.*\.gif)$" "http://backend.example.com/$1"

This will cause a local request for http://example.com/foo/bar.gif to be internally converted into a proxy request to http://backend.example.com/foo/bar.gif.

    ProxyPassMatch "^/(.*\.gif)$" "http://backend.example.com:8000/$1"


Start/Stop/Restart  service by : service httpd start/stop/restart