Intercepting Socket.getInputStream using AspectJ LTW

aop.xml

<!-- aop.xml with the options for launching LTW -->
<aspectj>
  <aspects>
      <aspect name="SocketOut"/>
  </aspects>
  <weaver options="-showWeaveInfo -Xset:weaveJavaPackages=true">
      <include within="java.net.Socket"/>
  </weaver>
</aspectj>

Client.java

// Client: reads a string from stdin and sends it to the Server. Waits for the same message from the server.

import java.io.*;
import java.net.*;

public class Client
{
  public static void main(String[] args) throws IOException
  {
    Socket socket = new Socket("127.0.0.1", 1234);
    BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

    BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
    String fromClient, fromServer;

    do
    {
      System.out.print("? ");
      fromClient = stdIn.readLine();
      out.println(fromClient);

      fromServer = in.readLine();
      System.out.println("Server: " + fromServer);
    } while (!fromServer.equals("quit"));

    in.close();
    out.close();
    socket.close();
  }
}

sample_output.out

**Client:**

WE'VE FOUND java.net.Socket.getInputStream!!!
>> 	Client.java:11
? hello
Server: hello
? bye
Server: bye


**Server:**

WE'VE FOUND java.net.Socket.getInputStream!!!
>> 	Server.java:20
Echoing #0 : hello
Echoing #1 : bye

Server.java

// Server: receives a string from the client, stores it in a local Redis server and echos it back to the client

import redis.clients.jedis.Jedis;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server
{
  public static void main(String[] args) throws IOException
  {
    // connect to redis
    Jedis jedis = new Jedis("localhost");
    // connect to streams
    ServerSocket serverSocket = new ServerSocket(1234);
    Socket socket = serverSocket.accept();
    BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);

    // send/rcv messages
    String fromClient;
    int keyCounter = 0;
    do
    {
      fromClient = in.readLine();
      String key = String.valueOf(keyCounter++);
      // set and get client message from Redis
      jedis.set(key, fromClient);
      System.out.println("Echoing #" + key + " : " + jedis.get(key));
      out.println(fromClient);
    }
    while (!fromClient.equals("quit"));

    // close all connections
    in.close();
    out.close();
    socket.close();
    serverSocket.close();
  }
}

SocketOut.aj

// Aspect: intercept all call join points where Socket.getInputStream is called and prints the source location
// It's called in both Server.java and Client.java, but it's also called upon Redis.set (Server.java:31). 
// Only the join points at the Server.java and Client.java are woven.

public aspect SocketOut
{
  after(): !within(SocketOut) && call(* java.net.Socket.getInputStream(..))
  {
    System.out.println("WE'VE FOUND java.net.Socket.getInputStream!!!");
    System.out.println(">> \t" + thisJoinPoint.getSourceLocation());
  }
}