Java-Buddy

Here are examples of Java SSL Server and Client.



JavaSSLServer.java

package javasslserver;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.net.ssl.SSLServerSocketFactory;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaSSLServer {
 
 static final int port = 8000;
 public static void main(String[] args) {
 
 
 SSLServerSocketFactory sslServerSocketFactory = 
 (SSLServerSocketFactory)SSLServerSocketFactory.getDefault();
 
 try {
 ServerSocket sslServerSocket = 
 sslServerSocketFactory.createServerSocket(port);
 System.out.println("SSL ServerSocket started");
 System.out.println(sslServerSocket.toString());
 
 Socket socket = sslServerSocket.accept();
 System.out.println("ServerSocket accepted");
 
 PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
 try (BufferedReader bufferedReader = 
 new BufferedReader(
 new InputStreamReader(socket.getInputStream()))) {
 String line;
 while((line = bufferedReader.readLine()) != null){
 System.out.println(line);
 out.println(line);
 }
 }
 System.out.println("Closed");
 
 } catch (IOException ex) {
 Logger.getLogger(JavaSSLServer.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 }
 
}

JavaSSLClient.java

package javasslclient;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.net.ssl.SSLSocketFactory;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaSSLClient {
 
 static final int port = 8000;
 public static void main(String[] args) {
 
 SSLSocketFactory sslSocketFactory = 
 (SSLSocketFactory)SSLSocketFactory.getDefault();
 try {
 Socket socket = sslSocketFactory.createSocket("localhost", port);
 PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
 try (BufferedReader bufferedReader = 
 new BufferedReader(
 new InputStreamReader(socket.getInputStream()))) {
 Scanner scanner = new Scanner(System.in);
 while(true){
 System.out.println("Enter something:");
 String inputLine = scanner.nextLine();
 if(inputLine.equals("q")){
 break;
 }
 
 out.println(inputLine);
 System.out.println(bufferedReader.readLine());
 }
 }
 
 } catch (IOException ex) {
 Logger.getLogger(JavaSSLClient.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 
 }
 
}

Without keystore, both the server and client will fail. This video show how to generate keystore using keytool program. Then run server and client with keystore and password.


Type the following command in your command window to create a keystore named examplestore and to generate keys:

$ keytool -genkey -alias signFiles -keystore examplestore

You will be prompted to enter passwords for the key and keystore. The password in this example is "password".

(reference: https://docs.oracle.com/javase/tutorial/security/toolsign/step3.html)

Run SSL server and client by entering the commands:
$ java -jar -Djavax.net.ssl.keyStore=keystore -Djavax.net.ssl.keyStorePassword=password "...JavaSSLServer.jar"
$ java -jar -Djavax.net.ssl.trustStore=keystore -Djavax.net.ssl.trustStorePassword=password "...JavaSSLClient.jar"

It's modified version of last example "Read csv file, display in JavaFX TableView", with the job run in background thread. I also add dummy delay to simulate long time operation in background thread.


JavaFXCSVTableView.java

package javafxcsvtableview;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaFXCSVTableView extends Application {
 public class Record {
 //Assume each record have 6 elements, all String
 private SimpleStringProperty f1, f2, f3, f4, f5, f6;
 public String getF1() {
 return f1.get();
 }
 public String getF2() {
 return f2.get();
 }
 public String getF3() {
 return f3.get();
 }
 public String getF4() {
 return f4.get();
 }
 public String getF5() {
 return f5.get();
 }
 public String getF6() {
 return f6.get();
 }
 Record(String f1, String f2, String f3, String f4,
 String f5, String f6) {
 this.f1 = new SimpleStringProperty(f1);
 this.f2 = new SimpleStringProperty(f2);
 this.f3 = new SimpleStringProperty(f3);
 this.f4 = new SimpleStringProperty(f4);
 this.f5 = new SimpleStringProperty(f5);
 this.f6 = new SimpleStringProperty(f6);
 }
 }
 private final TableView<Record> tableView = new TableView<>();
 private final ObservableList<Record> dataList
 = FXCollections.observableArrayList();
 @Override
 public void start(Stage primaryStage) {
 primaryStage.setTitle("java-buddy.blogspot.com");
 Group root = new Group();
 TableColumn columnF1 = new TableColumn("f1");
 columnF1.setCellValueFactory(
 new PropertyValueFactory<>("f1"));
 TableColumn columnF2 = new TableColumn("f2");
 columnF2.setCellValueFactory(
 new PropertyValueFactory<>("f2"));
 TableColumn columnF3 = new TableColumn("f3");
 columnF3.setCellValueFactory(
 new PropertyValueFactory<>("f3"));
 TableColumn columnF4 = new TableColumn("f4");
 columnF4.setCellValueFactory(
 new PropertyValueFactory<>("f4"));
 TableColumn columnF5 = new TableColumn("f5");
 columnF5.setCellValueFactory(
 new PropertyValueFactory<>("f5"));
 TableColumn columnF6 = new TableColumn("f6");
 columnF6.setCellValueFactory(
 new PropertyValueFactory<>("f6"));
 tableView.setItems(dataList);
 tableView.getColumns().addAll(
 columnF1, columnF2, columnF3, columnF4, columnF5, columnF6);
 VBox vBox = new VBox();
 vBox.setSpacing(10);
 vBox.getChildren().add(tableView);
 root.getChildren().add(vBox);
 primaryStage.setScene(new Scene(root, 700, 250));
 primaryStage.show();
 //readCSV();
 
 //run in background thread
 new Thread() {
 
 @Override
 public void run() {
 readCSV();
 };
 
 }.start();
 
 }
 private void readCSV() {
 
 System.out.println("Platform.isFxApplicationThread(): "
 + Platform.isFxApplicationThread());
 String CsvFile = "/home/buddy/test/test.csv";
 String FieldDelimiter = ",";
 BufferedReader br;
 try {
 br = new BufferedReader(new FileReader(CsvFile));
 String line;
 while ((line = br.readLine()) != null) {
 String[] fields = line.split(FieldDelimiter, -1);
 Record record = new Record(fields[0], fields[1], fields[2],
 fields[3], fields[4], fields[5]);
 dataList.add(record);
 //Add delay to simulate long time operation
 try {
 Thread.sleep(2000);
 } catch (InterruptedException ex) {
 Logger.getLogger(JavaFXCSVTableView.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 }
 } catch (FileNotFoundException ex) {
 Logger.getLogger(JavaFXCSVTableView.class.getName())
 .log(Level.SEVERE, null, ex);
 } catch (IOException ex) {
 Logger.getLogger(JavaFXCSVTableView.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 }
 public static void main(String[] args) {
 launch(args);
 }
}

Java example read csv file and display the content in JavaFX TableView.

To know how to prepare the csv file, and simple read csv file, refer to last post.


JavaFXCSVTableView.java

package javafxcsvtableview;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaFXCSVTableView extends Application {
 public class Record {
 //Assume each record have 6 elements, all String
 private SimpleStringProperty f1, f2, f3, f4, f5, f6;
 public String getF1() {
 return f1.get();
 }
 public String getF2() {
 return f2.get();
 }
 public String getF3() {
 return f3.get();
 }
 public String getF4() {
 return f4.get();
 }
 public String getF5() {
 return f5.get();
 }
 public String getF6() {
 return f6.get();
 }
 Record(String f1, String f2, String f3, String f4,
 String f5, String f6) {
 this.f1 = new SimpleStringProperty(f1);
 this.f2 = new SimpleStringProperty(f2);
 this.f3 = new SimpleStringProperty(f3);
 this.f4 = new SimpleStringProperty(f4);
 this.f5 = new SimpleStringProperty(f5);
 this.f6 = new SimpleStringProperty(f6);
 }
 }
 private final TableView<Record> tableView = new TableView<>();
 private final ObservableList<Record> dataList
 = FXCollections.observableArrayList();
 @Override
 public void start(Stage primaryStage) {
 primaryStage.setTitle("java-buddy.blogspot.com");
 Group root = new Group();
 TableColumn columnF1 = new TableColumn("f1");
 columnF1.setCellValueFactory(
 new PropertyValueFactory<>("f1"));
 TableColumn columnF2 = new TableColumn("f2");
 columnF2.setCellValueFactory(
 new PropertyValueFactory<>("f2"));
 TableColumn columnF3 = new TableColumn("f3");
 columnF3.setCellValueFactory(
 new PropertyValueFactory<>("f3"));
 TableColumn columnF4 = new TableColumn("f4");
 columnF4.setCellValueFactory(
 new PropertyValueFactory<>("f4"));
 TableColumn columnF5 = new TableColumn("f5");
 columnF5.setCellValueFactory(
 new PropertyValueFactory<>("f5"));
 TableColumn columnF6 = new TableColumn("f6");
 columnF6.setCellValueFactory(
 new PropertyValueFactory<>("f6"));
 tableView.setItems(dataList);
 tableView.getColumns().addAll(
 columnF1, columnF2, columnF3, columnF4, columnF5, columnF6);
 VBox vBox = new VBox();
 vBox.setSpacing(10);
 vBox.getChildren().add(tableView);
 root.getChildren().add(vBox);
 primaryStage.setScene(new Scene(root, 700, 250));
 primaryStage.show();
 readCSV();
 }
 private void readCSV() {
 String CsvFile = "/home/buddy/test/test.csv";
 String FieldDelimiter = ",";
 BufferedReader br;
 try {
 br = new BufferedReader(new FileReader(CsvFile));
 String line;
 while ((line = br.readLine()) != null) {
 String[] fields = line.split(FieldDelimiter, -1);
 Record record = new Record(fields[0], fields[1], fields[2],
 fields[3], fields[4], fields[5]);
 dataList.add(record);
 }
 } catch (FileNotFoundException ex) {
 Logger.getLogger(JavaFXCSVTableView.class.getName())
 .log(Level.SEVERE, null, ex);
 } catch (IOException ex) {
 Logger.getLogger(JavaFXCSVTableView.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 }
 public static void main(String[] args) {
 launch(args);
 }
}

Next post show how to do the job in background.

This example show how to read csv file using Java.


Prepare:
- Create a spreadsheet:


- Export as csv file:


- The exported csv file in text format:


Using java to read the csv file and print the content:

package javareadcsv;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaReadCSV {
 
 static String CsvFile = "/home/buddy/test/test.csv";
 static String FieldDelimiter = ",";
 public static void main(String[] args) throws IOException {
 BufferedReader br;
 
 try {
 br = new BufferedReader(new FileReader(CsvFile));
 
 String line;
 while ((line = br.readLine()) != null) {
 String[] fields = line.split(FieldDelimiter, -1);
 System.out.print(fields.length + "-");
 for(String s : fields){
 System.out.print(s);
 System.out.print(":");
 }
 System.out.println();
 }
 
 } catch (FileNotFoundException ex) {
 Logger.getLogger(JavaReadCSV.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 
 }
 
}

To display the content with JavaFX TableView, read next post.

Java example using java.util.function.Supplier to get input from java.util.Scanner.


JavaSupplier.java

package javasupplier;
import java.util.Scanner;
import java.util.function.Supplier;
import java.util.stream.Stream;
public class JavaSupplier {
 public static void main(String[] args) {
 Supplier<String> msg = ()-> "http://java-buddy.blogspot.com/";
 System.out.println(msg.get());
 System.out.println();
 
 Scanner scanner = new Scanner(System.in);
 Supplier<String> scannerNext = () -> scanner.next();
 System.out.println("Enter something, 'q' to quit");
 
 Stream.generate(scannerNext)
 .map(s -> {
 System.out.println(s);
 return s;
 })
 .allMatch(s -> !"q".equals(s));
 }
 
}

Java example to get MAC address using NetworkInterface:

package javamyip;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaMyIP {
 public static void main(String[] args) {
 displayMyIP();
 }
 
 static void displayMyIP(){
 Enumeration<NetworkInterface> nets;
 try {
 nets = NetworkInterface.getNetworkInterfaces();
 for (NetworkInterface netint : Collections.list(nets)){
 System.out.printf(netint.getDisplayName() +"\n");
 Enumeration<InetAddress> inetAddresses = netint.getInetAddresses();
 for (InetAddress inetAddress : Collections.list(inetAddresses)) {
 System.out.printf("InetAddress: %s\n", inetAddress);
 }
 
 byte[] mac = netint.getHardwareAddress();
 if(mac != null){
 StringBuilder macAddr = new StringBuilder();
 for (int i = 0; i < mac.length; i++) {
 macAddr.append(String.format("%02X%s", mac[i], (i < mac.length - 1) ? ":" : "")); 
 }
 System.out.printf("Hardware address (MAC): [%s]\n", macAddr.toString());
 }
 
 System.out.printf("\n");
 }
 } catch (SocketException ex) {
 Logger.getLogger(JavaMyIP.class.getName()).log(Level.SEVERE, null, ex);
 }
 }
}

Java example to list Network Interface Addresses and IP:

package javamyip;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaMyIP {
 public static void main(String[] args) {
 displayMyIP();
 }
 
 static void displayMyIP(){
 Enumeration<NetworkInterface> nets;
 try {
 nets = NetworkInterface.getNetworkInterfaces();
 for (NetworkInterface netint : Collections.list(nets)){
 System.out.printf(netint.getDisplayName() +"\n");
 Enumeration<InetAddress> inetAddresses = netint.getInetAddresses();
 for (InetAddress inetAddress : Collections.list(inetAddresses)) {
 System.out.printf("InetAddress: %s\n", inetAddress);
 }
 System.out.printf("\n");
 }
 } catch (SocketException ex) {
 Logger.getLogger(JavaMyIP.class.getName()).log(Level.SEVERE, null, ex);
 }
 }
}

Can use functional operations in Java 8 (auto suggested by Netbeans):

package javamyip;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Collections;
import java.util.Enumeration;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 * @web http://java-buddy.blogspot.com/
 */
public class JavaMyIP {
 public static void main(String[] args) {
 displayMyIP();
 }
 
 static void displayMyIP(){
 Enumeration<NetworkInterface> nets;
 try {
 nets = NetworkInterface.getNetworkInterfaces();
 Collections.list(nets).stream().map((netint) -> {
 System.out.printf(netint.getDisplayName() +"\n");
 return netint;
 }).map((netint) -> netint.getInetAddresses()).map((inetAddresses) -> {
 Collections.list(inetAddresses).stream().forEach((inetAddress) -> {
 System.out.printf("InetAddress: %s\n", inetAddress);
 });
 return inetAddresses;
 }).forEach((_item) -> {
 System.out.printf("\n");
 });
 } catch (SocketException ex) {
 Logger.getLogger(JavaMyIP.class.getName()).log(Level.SEVERE, null, ex);
 }
 }
}

Create ServerSocket by calling constructor ServerSocket(int port) with port = 0, the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling getLocalPort.

Example:

package javaechoserver;
import java.io.IOException;
import java.net.ServerSocket;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
 *
 * @web http://java-buddy.blogspot.com/
 */
public class JavaEchoServer {
 public static void main(String[] args) {
 ServerSocket serverSocket = null;
 try {
 //Get a available port by passing 0 
 serverSocket = new ServerSocket(0);
 int port = serverSocket.getLocalPort();
 System.out.println("Port : " + port);
 
 } catch (IOException ex) {
 Logger.getLogger(JavaEchoServer.class.getName())
 .log(Level.SEVERE, null, ex);
 } finally {
 if (serverSocket != null){
 try {
 serverSocket.close();
 } catch (IOException ex) {
 Logger.getLogger(JavaEchoServer.class.getName())
 .log(Level.SEVERE, null, ex);
 }
 }
 }
 }
 
}

Master the principles and techniques of multithreaded programming with the Java 8 Concurrency API

Mastering Concurrency Programming with Java 8

About This Book

• Implement concurrent applications using the Java 8 Concurrency API and its new components
• Improve the performance of your applications or process more data at the same time, taking advantage of all of your resources.
• Construct real-world examples related to machine learning, data mining, image processing, and client/server environments

Who This Book Is For
If you are a competent Java developer with a good understanding of concurrency but have no knowledge of how to effectively implement concurrent programs or use streams to make processes more efficient, then this book is for you.

What You Will Learn

• Design concurrent applications by converting a sequential algorithm into a concurrent one
• Discover how to avoid all the possible problems you can get in concurrent algorithms
• Use the Executor framework to manage concurrent tasks without creating threads
• Extend and modify Executors to adapt their behavior to your needs
• Solve problems using the divide and conquer technique and the Fork/Join framework
• Process massive data sets with parallel streams and Map/Reduce implementation
• Control data-race conditions using concurrent data structures and synchronization mechanisms
• Test and monitor concurrent applications

In Detail
Concurrency programming allows several large tasks to be divided into smaller sub-tasks, which are further processed as individual tasks that run in parallel. All the sub-tasks are combined together once the required results are achieved; they are then merged to get the final output. The whole process is very complex. This process goes from the design of concurrent algorithms to the testing phase where concurrent applications need extra attention. Java includes a comprehensive API with a lot of ready-to-use components to implement powerful concurrency applications in an easy way, but with a high flexibility to adapt these components to your needs.

The book starts with a full description of design principles of concurrent applications and how to parallelize a sequential algorithm. We'll show you how to use all the components of the Java Concurrency API from basics to the most advanced techniques to implement them in powerful concurrency applications in Java.

You will be using real-world examples of complex algorithms related to machine learning, data mining, natural language processing, image processing in client / server environments. Next, you will learn how to use the most important components of the Java 8 Concurrency API: the Executor framework to execute multiple tasks in your applications, the phaser class to implement concurrent tasks divided into phases, and the Fork/Join framework to implement concurrent tasks that can be split into smaller problems (using the divide and conquer technique). Toward the end, we will cover the new inclusions in Java 8 API, the Map and Reduce model, and the Map and Collect model. The book will also teach you about the data structures and synchronization utilities to avoid data-race conditions and other critical problems. Finally, the book ends with a detailed description of the tools and techniques that you can use to test a Java concurrent application.

Style and approach
A complete guide implementing real-world examples with algorithms related to machine learning, data mining, and natural language processing in client/server environments. All the examples are explained in a step-by-step approach.