//HTTP, SMTP, POP

// HTTP

import java.io.*;
import java.net.*;
public class HTTP
{
public static void main(String[] args)
{
try
{
OutputStream to_file = new FileOutputStream("f:\\temp.txt");
URL url = new
URL("http://www.wickedlysmart.com/HeadFirst/HeadFirstJava/HeadFirstJavaIndex.html");
String protocol = url.getProtocol();
String host = url.getHost();
int port = url.getPort();
if(port == -1) port = 80;
String filename =url.getFile();
System.out.println(filename);
Socket socket = new Socket(host, port);
InputStream from_server = socket.getInputStream();
PrintWriter to_server = new PrintWriter(socket.getOutputStream());
to_server.print("Get" + filename +"\n\n");
to_server.flush();
byte[] buffer = new byte[4096];
int byte_read;
while((byte_read = from_server.read(buffer)) != -1)
{
to_file.write(buffer,0,byte_read);
System.out.print((char)byte_read);
}
socket.close();
to_file.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}}

//SMTP
import java.io.*;
import java.net.Socket;
public class SMTPClient {
public static void main(String[] args) throws Exception {
String results = send("localhost", 25, "sender@somewhere.com", "localhost/localdomain", "Test Email",
"<b>You got mail!</b>");
System.out.println(results);
}
public static String send(String host,int port,String from,String to,String subject,
String message) throws Exception
{
StringBuffer buffer = new StringBuffer();
try {
Socket smtpSocket = new Socket(host, port);
DataOutputStream output = new
DataOutputStream(smtpSocket.getOutputStream());
BufferedReader input =new BufferedReader(new InputStreamReader(
new
DataInputStream(smtpSocket.getInputStream())));
try {
read(input, buffer);
send(output, "HELO localhost.localdomain\r\n", buffer);
read(input, buffer);
send(output, "MAIL FROM: " + from + "\r\n", buffer);
read(input, buffer);
send(output, "RCPT to: " + to + "\r\n", buffer);
read(input, buffer);
send(output, "DATA\r\n", buffer);
read(input, buffer);
send(output, "Subject: " + subject + "\r\n", buffer);
send(output, message, buffer);
send(output, "\r\n.\r\n", buffer);
read(input, buffer);
smtpSocket.close();
}
catch (IOException e) {
System.out.println("Cannot send email as an error occurred.");
}
}
catch (Exception e) {
System.out.println("Host unknown");
}
return buffer.toString();
}
private static void send(DataOutputStream output,String data,StringBuffer buffer)
throws IOException
{
output.writeBytes(data);
buffer.append(data);
}
private static void read(BufferedReader br, StringBuffer buffer) throws IOException
{
int c;
while ((c = br.read()) != -1)
{
buffer.append((char) c);
if (c == '\n')
{
break;
}
}
}
}

//POP
import java.io.*;
import java.net.*;
import java.util.*;
public class Pop3ClientDemo
{
protected int port = 110;
protected String hostname = "localhost";
protected String username = "";
protected String password = "";
protected Socket socket;
protected BufferedReader br;
protected PrintWriter pw;
// Constructs a new instance of the POP3 client
public Pop3ClientDemo() throws Exception
{
try
{
// Get user input
getInput();
// Get mail messages
displayEmails();
}
catch(Exception e)
{
System.err.println ("Error occured - details follow");
e.printStackTrace();
System.out.println(e.getMessage());
}
}
// Returns TRUE if POP response indicates success, FALSE if failure
protected boolean responseIsOk() throws Exception
{
String line = br.readLine();
System.out.println("< "+line);
return line.toUpperCase().startsWith("+OK");
}
// Reads a line from the POP server, and displays it to screen
protected String readLine(boolean debug) throws Exception
{
String line = br.readLine();
// Append a < character to indicate this is a server protocol response
if (debug)
System.out.println("< "+line);
else
System.out.println(line);
return line;
}
// Writes a line to the POP server, and displays it to the screen
protected void writeMsg(String msg) throws Exception
{
pw.println(msg);
pw.flush();
System.out.println("> "+msg);
}
// Close all writers, streams and sockets
protected void closeConnection() throws Exception
{
pw.flush();
pw.close();
br.close();
socket.close();
}
// Send the QUIT command, and close connection
protected void sendQuit() throws Exception
{
System.out.println("Sending QUIT");
writeMsg("QUIT");
readLine(true);
System.out.println("Closing Connection");
closeConnection();
}
// Display emails in a message
protected void displayEmails() throws Exception
{
BufferedReader userinput = new BufferedReader( new InputStreamReader
(System.in) );
System.out.println("Displaying mailbox with protocol commands and responses below");
System.out.println("--------------------------------------------------------------");
// Open a connection to POP3 server
System.out.println("Opening Socket");
socket = new Socket(this.hostname, this.port);
br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
pw = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()));
// If response from server is not okay
if(! responseIsOk())
{
socket.close();
throw new Exception("Invalid POP3 Server");
}
// Login by sending USER and PASS commands
System.out.println("Sending username");
writeMsg("USER "+this.username);
if(!responseIsOk())
{
sendQuit();
throw new Exception("Invalid username");
}
System.out.println("Sending password");
writeMsg("PASS "+this.password);
if(!responseIsOk())
{
sendQuit();
throw new Exception("Invalid password");
}
// Get mail count from server ....
System.out.println("Checking mail");
writeMsg("STAT");
// ... and parse for number of messages
String line = readLine(true);
StringTokenizer tokens = new StringTokenizer(line," ");
tokens.nextToken();
int messages = Integer.parseInt(tokens.nextToken());
int maxsize = Integer.parseInt(tokens.nextToken());
if (messages == 0)
{
System.out.println ("There are no messages.");
sendQuit();
return;
}
System.out.println ("There are " + messages + " messages.");
System.out.println("Press enter to continue.");
userinput.readLine();
for(int i = 1; i <= messages ; i++)
{
System.out.println("Retrieving message number "+i);
writeMsg("RETR "+i);
System.out.println("--------------------");
line = readLine(false);
while(line != null && !line.equals("."))
{
line = readLine(false);
}
System.out.println("--------------------");
System.out.println("Press enter to continue. To stop, type Q then enter");
String response = userinput.readLine();
if (response.toUpperCase().startsWith("Q"))
break;
}
sendQuit();
}
public static void main(String[] args) throws Exception
{
Pop3ClientDemo client = new Pop3ClientDemo();
}
// Read user input
protected void getInput() throws Exception
{
String data=null;
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.print("Please enter POP3 server hostname:");
data = br.readLine();
if(data == null || data.equals("")) hostname="localhost";
else
hostname=data;
System.out.print("Please enter mailbox username:");
data = br.readLine();
if(!(data == null || data.equals("")))
username=data;
System.out.print("Please enter mailbox password:");
data = br.readLine();
if(!(data == null || data.equals("")))
password=data;
}
}