From d86712952b3e00533350aba0e261b65d6d0fc4e2 Mon Sep 17 00:00:00 2001
From: 0qln <0qln@proton.me>
Date: Thu, 13 Nov 2025 09:39:31 +0100
Subject: [PATCH] praktikum-5/aufgabe-4

---
 .envrc                           |  1 +
 .gitignore                       |  1 +
 build.xml                        |  1 +
 praktikum-5/aufgabe4/Client.java | 53 ++++++++++++++++++++++++++++++++
 praktikum-5/aufgabe4/Server.java | 51 ++++++++++++++++++++++++++++++
 5 files changed, 107 insertions(+)
 create mode 100644 .envrc
 create mode 100644 praktikum-5/aufgabe4/Client.java
 create mode 100644 praktikum-5/aufgabe4/Server.java

diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..3550a30
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake
diff --git a/.gitignore b/.gitignore
index 8005ca5..b28e9a9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .jdtls
 build
 result
+.direnv
diff --git a/build.xml b/build.xml
index f9af5f3..35833de 100644
--- a/build.xml
+++ b/build.xml
@@ -15,6 +15,7 @@
         <javac srcdir="${src.dir}" destdir="${classes.dir}"
                includeantruntime="false" debug="true">
             <compilerarg value="-Xlint:unchecked"/>
+            <exclude name="**/.direnv/**"/>
         </javac>
     </target>
 
diff --git a/praktikum-5/aufgabe4/Client.java b/praktikum-5/aufgabe4/Client.java
new file mode 100644
index 0000000..495ba31
--- /dev/null
+++ b/praktikum-5/aufgabe4/Client.java
@@ -0,0 +1,53 @@
+package praktikum5.aufgabe4;
+
+import java.net.Socket;
+import java.net.UnknownHostException;
+import java.util.Scanner;
+import java.io.OutputStreamWriter;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+public class Client {
+    private int port;
+
+    public Client(int port) {
+        this.port = port;
+    }
+
+    public String send(String msg) throws IOException {
+        var socket = new Socket("localhost", port);
+        var out = socket.getOutputStream();
+        var in = socket.getInputStream();
+        var reader = new InputStreamReader(in);
+        var writer = new OutputStreamWriter(out);
+
+        writer.write(msg);
+        writer.flush();
+        socket.shutdownOutput();
+
+        var response = "";
+        var curr = reader.read();
+        while (curr != -1) {
+            response += (char)curr;
+            curr = reader.read();
+        }
+        reader.close();
+
+        return response;
+    }
+
+    public static void main(String[] args) {
+        try {
+            int port = 4711;
+            var client = new Client(port);
+            var reader = new Scanner(System.in);
+            while (true) {
+                var msg = reader.nextLine();
+                var response = client.send(msg);
+                System.out.println("Response: " + response);
+            }
+        } catch (Exception e) {
+            System.out.println(e);
+        }
+    }
+}
diff --git a/praktikum-5/aufgabe4/Server.java b/praktikum-5/aufgabe4/Server.java
new file mode 100644
index 0000000..9ffd485
--- /dev/null
+++ b/praktikum-5/aufgabe4/Server.java
@@ -0,0 +1,51 @@
+package praktikum5.aufgabe4;
+
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.net.ServerSocket;
+import java.net.Socket;
+
+public class Server {
+    private ServerSocket socket;
+
+    public Server(ServerSocket socket) {
+        this.socket = socket;
+    }
+
+    public String echo() throws IOException {
+        var clientSocket = socket.accept();
+        var in = clientSocket.getInputStream();
+        var out = clientSocket.getOutputStream();
+        var reader = new InputStreamReader(in);
+        var writer = new OutputStreamWriter(out);
+
+        var msg = "";
+        var curr = reader.read();
+        while (curr != -1) {
+            msg += (char)curr;
+            curr = reader.read();
+        }
+
+        writer.write(msg);
+        writer.flush();
+        writer.close();
+
+        return msg;
+    }
+
+    public static void main(String[] args) {
+        try {
+            int port = 4711;
+            var socket = new ServerSocket(port);
+            var server = new Server(socket);
+            System.out.println("Listening on port " + port);
+            while (true) {
+                var msg = server.echo();
+                System.out.println("Request: " + msg);
+            }
+        } catch (Exception e) {
+            System.out.println(e);
+        }
+    }
+}