Java Language TCP NIO Socket EchoServer&Client Sample Source

JAVA NIO Socket EchoServer

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;
import java.util.concurrent.Executors;
 
public class EchoServer implements Runnable {
 
    private InetSocketAddress listenAddress;
    
    public EchoServer(String address, int port) {
        listenAddress = new InetSocketAddress(address, port);
    }

    public void run() {
        try (Selector selector = Selector.open()) {
        try (ServerSocketChannel serverChannel = ServerSocketChannel.open()) {
            serverChannel.configureBlocking(false);
            serverChannel.socket().bind(listenAddress);
            serverChannel.register(selector, SelectionKey.OP_ACCEPT);
            while (selector.select() > 0) {
                Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
                while (keys.hasNext()) {
                    SelectionKey key = keys.next();
                    keys.remove();
                    if (!key.isValid()) {
                        continue;
                    }
                    if (key.isAcceptable()) {
                        this.accept(selector, key);
                    } else if (key.isReadable()) {
                        this.receive(selector, key);
                    } else if (key.isWritable()) {
                        this.send(selector, key);
                    }
                }
            }
        }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void accept(Selector selector, SelectionKey key) {
        try {
            ServerSocketChannel serverChannel = (ServerSocketChannel) key.channel();
            SocketChannel channel = serverChannel.accept();
            channel.configureBlocking(false);
            Socket socket = channel.socket();
            SocketAddress remoteAddr = socket.getRemoteSocketAddress();
            System.out.println("Connected to: " + remoteAddr);
            StringBuffer sb = new StringBuffer();
            channel.register(selector, SelectionKey.OP_WRITE, sb);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void receive(Selector selector, SelectionKey key) {
        try {
            SocketChannel channel = (SocketChannel) key.channel();
            channel.configureBlocking(false);
            Socket socket = channel.socket();
            ByteBuffer buffer = ByteBuffer.allocate(1024);
            int size = channel.read(buffer);
            if (size == -1) {
                SocketAddress remoteAddr = socket.getRemoteSocketAddress();
                System.out.println("Connection closed by client: " + remoteAddr);
                channel.close();
                socket.close();
                key.cancel();
                return;
            }
            byte[] data = new byte[size];
            System.arraycopy(buffer.array(), 0, data, 0, size);
            StringBuffer sb = (StringBuffer) key.attachment();
            sb.append(new String(data));
            if (sb.length() > 2 && sb.charAt(sb.length() - 2) == '@' && sb.charAt(sb.length() - 1) == '@') {
                String msg = sb.toString();
                sb.replace(159,160,"R");
                System.out.println(msg);
                if ("exit".equals(msg)) {
                    channel.close();
                    socket.close();
                    key.cancel();
                    return;
                }
                channel.register(selector, SelectionKey.OP_WRITE, sb);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    private void send(Selector selector, SelectionKey key) {
        try {
            SocketChannel channel = (SocketChannel) key.channel();
            channel.configureBlocking(false);
            StringBuffer sb = (StringBuffer) key.attachment();
            String data = sb.toString();
            sb.setLength(0);
            ByteBuffer buffer = ByteBuffer.wrap(data.getBytes());
            channel.write(buffer);
            channel.register(selector, SelectionKey.OP_READ, sb);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static void main(String[] args) {
        Executors.newSingleThreadExecutor().execute(new EchoServer("0.0.0.0", Integer.parseInt(args[0])));
    }
}

JAVA NIO Socket Client

import java.io.IOException;
import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SocketChannel;
import java.text.SimpleDateFormat;
import java.util.Calendar;
 
public class SocketClient extends Thread {
  
    private static String ipAddress = "";
    private static int port = 0;
    private static String filePath = "";
    private static int thcount = 0;
    private static int scount = 0;
    private static int totalcount= 1;

    public static void main(String[] args) throws IOException {
        ipAddress = args[0];
        port = Integer.parseInt(args[1]);
        filePath = args[2];
        thcount = Integer.parseInt(args[3]);
        scount = Integer.parseInt(args[4]);

        SocketClient c = new SocketClient();
    	for(int i=0; i<thcount; i++) {
        	new Thread(c).start();
	    }
    }

    public void run() {
        try { 
            InetSocketAddress hostAddress = new InetSocketAddress(ipAddress, port);
            SocketChannel client = SocketChannel.open(hostAddress);
            System.out.println("Client... connect to " + ipAddress + ":" + port);
            
            String threadName = Thread.currentThread().getName();
            long threadNumber = Thread.currentThread().getId();       	

            File f = new File(filePath);
            BufferedReader br = new BufferedReader(new FileReader(f));
            String message = br.readLine();
            br.close();
            byte[] bMsg = message.getBytes();

            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
            Calendar c1 = Calendar.getInstance();
            String strToday = sdf.format(c1.getTime());

            ByteBuffer buffer = ByteBuffer.allocate(message.length());

            for(int i=0; i<scount; i++) {
                String time = String.valueOf(System.nanoTime());
                System.arraycopy(strToday.getBytes(), 0, bMsg, 9, 8);
                System.arraycopy(time.getBytes(), 0, bMsg, 17, time.length());
                buffer.put(bMsg);
                buffer.flip();
                client.write(buffer);
                System.out.println("["+totalcount+"]["+threadNumber+"]send :[" + new String(buffer.array()).substring(0,100) + "...]");
                buffer.clear();
                client.read(buffer);
                System.out.println("["+totalcount+"]["+threadNumber+"]recv :[" + new String(buffer.array()).substring(0,100) + "...]");
                buffer.clear();
                totalcount++;
            } 
            client.close();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }
}

HTTP Client

import java.io.*;
import java.net.*;
import java.util.*;
import java.text.SimpleDateFormat;

public class HTTPClient {
    public static void post(String address, String postData) throws Exception {   

        URL url = new URL(address);
        byte[] postDataBytes = postData.toString().getBytes("UTF-8");

	    long sTime = System.currentTimeMillis();
        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
	    long eTime = System.currentTimeMillis();
	    System.out.println("Connect time : " + (eTime - sTime));

        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "text/plain; charset=UTF-8");
        conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.getOutputStream().write(postDataBytes);
        
        System.out.println("send : [" + new String(postDataBytes).substring(0,100) + "...]");

      	String return_code_from_server = null;
      	Map hmap = conn.getHeaderFields();
      	Set hkeys = hmap.keySet();
      	Iterator it = hkeys.iterator();
      	while (it.hasNext())
      	{
        	String hkey = (String)it.next();
        	Object value = hmap.get(hkey);
		    //System.out.println(hkey + ": " + value.toString());
        	if ((hkey == null) || (hkey.equals("null"))) {
          		return_code_from_server = value.toString();
          		//return_code_from_server = "[	HTTP/1.1 200 ]";
        	}

        	if ((return_code_from_server != null) && (return_code_from_server.trim().length() > 0))
        	{
          		int index = return_code_from_server.indexOf(" ");
          		int end_index = return_code_from_server.indexOf(" ", index + 1);
          		String reply_code = return_code_from_server.substring(index + 1, end_index);
        	}
      	}

        int responseCode = conn.getResponseCode(); 
        StringBuffer responseData = new StringBuffer(); 
        
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
	        in.close();
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            }
	        in.close(); 
        }
	    long dTime = System.currentTimeMillis();
	    System.out.println("Send Receive time : " + (dTime - eTime));
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }

    public static void get(String address) throws Exception {   

        URL url = new URL(address);

        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        conn.setDoOutput(true);
        conn.setUseCaches(false);

        System.out.println("send : [" + address + "]");

        int responseCode = conn.getResponseCode();         
        StringBuffer responseData = new StringBuffer(); 
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        }
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }    

    public static void main(String argv[]) throws Exception {
	
        BufferedReader reader = new BufferedReader(new FileReader(argv[0]));
        String postData = reader.readLine();
        reader.close();

        int loopCount = Integer.parseInt(argv[1]);
        byte[] bData = postData.getBytes();
        String address = "http://192.168.253.130:17001/ONLSCOMWE001-initial/EAICall";  

        SimpleDateFormat dtf = new SimpleDateFormat("yyyyMMdd");
        Calendar calendar = Calendar.getInstance();

        Date dateObj = calendar.getTime();
        String formattedDate = dtf.format(dateObj);

        System.arraycopy( formattedDate.getBytes(), 0, bData, 9, 8);

        for(int i=0; i<loopCount; i++) {
            System.arraycopy( (String.valueOf(System.currentTimeMillis())).getBytes(), 0, bData, 17, 13);
                post(address, new String(bData));
        }
    }

    public static String stringToHex(String s) {
        String result = "";

        for (int i = 0; i < s.length(); i++) {
            result += String.format("%02X ", (int) s.charAt(i));
        }

        return result;
    }
}

HTTPS Client

import java.io.*;
import java.net.*;
import javax.net.ssl.*;
import java.security.cert.*;
import java.util.*;
import java.text.SimpleDateFormat;

public class HTTPSClient_auth {
    public static void post(String address, String postData) throws Exception {   

        URL url = new URL(address);
        byte[] postDataBytes = postData.toString().getBytes("UTF-8");

        HttpsURLConnection conn = null;
	    long sTime = System.currentTimeMillis();
        conn = (HttpsURLConnection)url.openConnection();
	    conn.setDefaultHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        });
	    long eTime = System.currentTimeMillis();
	    System.out.println("Connect time : " + (eTime - sTime));

        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "text/plain; charset=UTF-8");
        conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.getOutputStream().write(postDataBytes);
        
        System.out.println("send : [" + new String(postDataBytes).substring(0,100) + "...]");

      	String return_code_from_server = null;
      	Map hmap = conn.getHeaderFields();
      	Set hkeys = hmap.keySet();
      	Iterator it = hkeys.iterator();
      	while (it.hasNext())
      	{
        	String hkey = (String)it.next();
        	Object value = hmap.get(hkey);
        	if ((hkey == null) || (hkey.equals("null"))) {
          		return_code_from_server = value.toString();
          		//return_code_from_server = "[	HTTP/1.1 200 ]";
        	}

        	if ((return_code_from_server != null) && (return_code_from_server.trim().length() > 0))
        	{
          		int index = return_code_from_server.indexOf(" ");
          		int end_index = return_code_from_server.indexOf(" ", index + 1);
          		String reply_code = return_code_from_server.substring(index + 1, end_index);
        	}
      	}

        int responseCode = conn.getResponseCode(); 
        StringBuffer responseData = new StringBuffer(); 
        
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        }
	    long dTime = System.currentTimeMillis();
	    System.out.println("Send Receive time : " + (dTime - eTime));
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }

    public static void get(String address) throws Exception {   

        URL url = new URL(address);
        HttpsURLConnection conn = null;
	    long sTime = System.currentTimeMillis();
        conn = (HttpsURLConnection)url.openConnection();
	    conn.setDefaultHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        });
	    long eTime = System.currentTimeMillis();
	    System.out.println("Connect time : " + (eTime - sTime));

        conn.setRequestMethod("GET");
        conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        conn.setDoOutput(true);
        conn.setUseCaches(false);

        System.out.println("send : [" + address + "]");

        int responseCode = conn.getResponseCode();         
        StringBuffer responseData = new StringBuffer(); 
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        }
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }    

    public static void main(String argv[]) throws Exception {
	
        BufferedReader reader = new BufferedReader(new FileReader(argv[0]));
        String postData = reader.readLine();
        reader.close();

        int loopCount = Integer.parseInt(argv[1]);
        byte[] bData = postData.getBytes();
        String address = "https://ism25-ap1:17002/ONLSCOMWE001-initial/EAICall";  

        SimpleDateFormat dtf = new SimpleDateFormat("yyyyMMdd");
        Calendar calendar = Calendar.getInstance();

        Date dateObj = calendar.getTime();
        String formattedDate = dtf.format(dateObj);

    	System.arraycopy( formattedDate.getBytes(), 0, bData, 9, 8);

        for(int i=0; i<loopCount; i++) {
            System.arraycopy( (String.valueOf(System.currentTimeMillis())).getBytes(), 0, bData, 17, 13);
                post(address, new String(bData));
        }
    }

    public static String stringToHex(String s) {
        String result = "";
        for (int i = 0; i < s.length(); i++) {
            result += String.format("%02X ", (int) s.charAt(i));
        }
        return result;
    }
}

HTTPS Client(no auth)

import java.io.*;
import java.net.*;
import javax.net.ssl.*;
import java.security.cert.*;
import java.util.*;
import java.text.SimpleDateFormat;

public class HTTPSClient {
    public static void post(String address, String postData) throws Exception {   

        URL url = new URL(address);
        byte[] postDataBytes = postData.toString().getBytes("UTF-8");

        HttpsURLConnection conn = null;

        long sTime = System.currentTimeMillis();
        trustAllHttpsCertificates();
        conn.setDefaultHostnameVerifier(new HostnameVerifier() {
            @Override
            public boolean verify(String hostname, SSLSession session) {
                return true;
            }
        });
        conn = (HttpsURLConnection)url.openConnection();
    	long eTime = System.currentTimeMillis();
	    System.out.println("Connect time : " + (eTime - sTime));

        conn.setRequestMethod("POST");
        conn.setRequestProperty("Content-Type", "text/plain; charset=UTF-8");
        conn.setRequestProperty("Content-Length", String.valueOf(postDataBytes.length));
        conn.setDoOutput(true);
        conn.setUseCaches(false);
        conn.getOutputStream().write(postDataBytes);
        
        System.out.println("send : [" + new String(postDataBytes).substring(0,100) + "...]");

      	String return_code_from_server = null;
      	Map hmap = conn.getHeaderFields();
      	Set hkeys = hmap.keySet();
      	Iterator it = hkeys.iterator();
      	while (it.hasNext())
      	{
        	String hkey = (String)it.next();
        	Object value = hmap.get(hkey);
		    //System.out.println(hkey + ": " + value.toString());
        	if ((hkey == null) || (hkey.equals("null"))) {
          		return_code_from_server = value.toString();
          		//return_code_from_server = "[	HTTP/1.1 200 ]";
        	}

        	if ((return_code_from_server != null) && (return_code_from_server.trim().length() > 0))
        	{
          		int index = return_code_from_server.indexOf(" ");
          		int end_index = return_code_from_server.indexOf(" ", index + 1);
          		String reply_code = return_code_from_server.substring(index + 1, end_index);
        	}
      	}

        int responseCode = conn.getResponseCode(); 
        StringBuffer responseData = new StringBuffer(); 
        
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        }
	    long dTime = System.currentTimeMillis();
	    System.out.println("Send Receive time : " + (dTime - eTime));
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }

    public static void get(String address) throws Exception {   

        URL url = new URL(address);

        HttpURLConnection conn = (HttpURLConnection)url.openConnection();
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Content-Type", "application/json; charset=UTF-8");
        conn.setDoOutput(true);
        conn.setUseCaches(false);

        System.out.println("send : [" + address + "]");

        int responseCode = conn.getResponseCode();         
        StringBuffer responseData = new StringBuffer(); 
        if (responseCode == HttpURLConnection.HTTP_OK || responseCode == HttpURLConnection.HTTP_CREATED) { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        } else { 
            BufferedReader in = new BufferedReader(new InputStreamReader(conn.getErrorStream())); 
            String inputLine; 
            while ((inputLine = in.readLine()) != null) { 
                responseData.append(inputLine); 
            } 
            in.close(); 
        }
        System.out.println("recv : [" + responseData.toString().substring(0,100) + "...]");
    }    

    public static void main(String argv[]) throws Exception {
	
        BufferedReader reader = new BufferedReader(new FileReader(argv[0]));
        String postData = reader.readLine();
        reader.close();

        int loopCount = Integer.parseInt(argv[1]);
        byte[] bData = postData.getBytes();
        String address = "https://192.168.253.130:17002/ONLSCOMWE001-initial/EAICall";  

        SimpleDateFormat dtf = new SimpleDateFormat("yyyyMMdd");
        Calendar calendar = Calendar.getInstance();

        Date dateObj = calendar.getTime();
        String formattedDate = dtf.format(dateObj);

	    System.arraycopy( formattedDate.getBytes(), 0, bData, 9, 8);

        for(int i=0; i<loopCount; i++) {
            System.arraycopy( (String.valueOf(System.currentTimeMillis())).getBytes(), 0, bData, 17, 13);
            post(address, new String(bData));
        }
    }

    public static String stringToHex(String s) {
        String result = "";
        for (int i = 0; i < s.length(); i++) {
            result += String.format("%02X ", (int) s.charAt(i));
        }
        return result;
    }

    private static void trustAllHttpsCertificates() throws Exception {
        TrustManager[] trustAllCerts = new TrustManager[1];
        TrustManager tm = new miTM();
        trustAllCerts[0] = tm;
        SSLContext sc = SSLContext.getInstance("SSL");
        sc.init(null, trustAllCerts, null);
        HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
    }

    static class miTM implements TrustManager,X509TrustManager {
        public X509Certificate[] getAcceptedIssuers() {
            return null;
        }
        public boolean isServerTrusted(X509Certificate[] certs) {
            return true;
        }
        public boolean isClientTrusted(X509Certificate[] certs) {
            return true;
        }
        public void checkServerTrusted(X509Certificate[] certs, String authType)
                throws CertificateException {
            return;
        }
        public void checkClientTrusted(X509Certificate[] certs, String authType)
                throws CertificateException {
            return;
        }
    }
}

HTTP Client (JDK11)

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.net.http.HttpClient.Version;
import java.net.http.HttpRequest.BodyPublisher;
import java.net.http.HttpRequest.BodyPublishers;

public class HTTPClientJDK11 {

    public static void get(String address, String[] headers) throws Exception {        
        HttpClient client = HttpClient.newBuilder().version(Version.HTTP_1_1).build();        
        String result = client.sendAsync(
        HttpRequest.newBuilder(new URI(address)).GET().headers(headers).build(), 
        HttpResponse.BodyHandlers.ofString()).thenApply(HttpResponse::body).get();
        System.out.println(result);
    }    
    
    public static void post(String address, String[] headers, BodyPublisher bp) throws Exception {        
        HttpClient client = HttpClient.newBuilder().version(Version.HTTP_1_1).build();        
        String result = client.sendAsync(
        HttpRequest.newBuilder(new URI(address)).POST(bp).headers(headers).build(), 
        HttpResponse.BodyHandlers.ofString()).thenApply(HttpResponse::body).get();
        System.out.println(result);
    }

    public static void main(String argv[]) throws Exception {
        String address = "http://localhost:29001";
        String headers[] = {    "Content-Type", "application/json;charset=UTF-8",
                                "Param1" , "data1",
                                "Param1", "data2"   };        
        BodyPublisher bp = BodyPublishers.ofString("{ data: \"Data\"}");
        post(address, headers, bp);
    }
}