asyncronous channel apis (#839)

* made changes to java reflection

* removed redundant method makeSound in Animal abstract class

* added project for play-framework article

* added project for regex

* changed regex project from own model to core-java

* added project for routing in play

* made changes to regex project

* refactored code for REST API with Play project

* refactored student store indexing to zero base

* added unit tests, removed bad names

* added NIO Selector project under core-java module

* requested changes made

* added project for nio2

* standardized exception based tests

* fixed exception based tests

* removed redundant files

* added network interface project

* used UUID other than timestamps

* fixed network interface tests

* removed filetest change

* made changes to NIO2 FileTest names

* added project for asyncronous channel apis

* added project for NIO2 advanced filesystems APIS

core-java/src/main/java/com/baeldung/java/nio2/visitor/FileSearchExample.java

@@ -0,0 +1,60 @@
+package com.baeldung.java.nio2.visitor;
+
+import static java.nio.file.FileVisitResult.CONTINUE;
+import static java.nio.file.FileVisitResult.TERMINATE;
+
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.BasicFileAttributes;
+
+public class FileSearchExample implements FileVisitor<Path> {
+    private static String FILE_NAME;
+    private static Path START_DIR;
+
+    public FileSearchExample(String fileName, Path startingDir) {
+        FILE_NAME = fileName;
+        START_DIR = startingDir;
+    }
+
+    @Override
+    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
+        String fileName = file.getFileName().toString();
+        if (FILE_NAME.equals(fileName)) {
+            System.out.println("File found: " + file.toString());
+            return TERMINATE;
+        }
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
+        System.out.println("Failed to access file: " + file.toString());
+        return CONTINUE;
+    }
+
+    @Override
+    public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
+        boolean finishedSearch = Files.isSameFile(dir, START_DIR);
+        if (finishedSearch) {
+            System.out.println("File:" + FILE_NAME + " not found");
+            return TERMINATE;
+        }
+        return CONTINUE;
+    }
+
+    public static void main(String[] args) throws IOException {
+        Path startingDir = Paths.get("C:/Users/new/Desktop");
+        FileSearchExample crawler = new FileSearchExample("hibernate.txt", startingDir);
+        Files.walkFileTree(startingDir, crawler);
+    }
+
+}

core-java/src/main/java/com/baeldung/java/nio2/visitor/FileVisitorImpl.java

@@ -0,0 +1,30 @@
+package com.baeldung.java.nio2.visitor;
+
+import java.io.IOException;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+
+public class FileVisitorImpl implements FileVisitor<Path> {
+
+    @Override
+    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) {
+        return null;
+    }
+
+    @Override
+    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
+        return null;
+    }
+
+    @Override
+    public FileVisitResult visitFileFailed(Path file, IOException exc) {       
+        return null;
+    }
+
+    @Override
+    public FileVisitResult postVisitDirectory(Path dir, IOException exc) {    
+        return null;
+    }
+}

core-java/src/main/java/com/baeldung/java/nio2/watcher/DirectoryWatcherExample.java

@@ -0,0 +1,25 @@
+package com.baeldung.java.nio2.watcher;
+
+import java.io.IOException;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardWatchEventKinds;
+import java.nio.file.WatchEvent;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchService;
+
+public class DirectoryWatcherExample {
+    public static void main(String[] args) throws IOException, InterruptedException {
+        WatchService watchService = FileSystems.getDefault().newWatchService();
+        Path path = Paths.get(System.getProperty("user.home"));
+        path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE, StandardWatchEventKinds.ENTRY_DELETE, StandardWatchEventKinds.ENTRY_MODIFY);
+        WatchKey key;
+        while ((key = watchService.take()) != null) {
+            for (WatchEvent<?> event : key.pollEvents()) {
+                System.out.println("Event kind:" + event.kind() + ". File affected: " + event.context() + ".");
+            }
+            key.reset();
+        }
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoClient.java

@@ -0,0 +1,82 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+public class AsyncEchoClient {
+    private AsynchronousSocketChannel client;
+    private Future<Void> future;
+    private static AsyncEchoClient instance;
+
+    private AsyncEchoClient() {
+        try {
+            client = AsynchronousSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            future = client.connect(hostAddress);
+            start();
+
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static AsyncEchoClient getInstance() {
+        if (instance == null)
+            instance = new AsyncEchoClient();
+        return instance;
+    }
+
+    private void start() {
+        try {
+            future.get();
+        } catch (InterruptedException | ExecutionException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public String sendMessage(String message) {
+        byte[] byteMsg = new String(message).getBytes();
+        ByteBuffer buffer = ByteBuffer.wrap(byteMsg);
+        Future<Integer> writeResult = client.write(buffer);
+
+        while (!writeResult.isDone()) {
+            // do nothing
+        }
+        buffer.flip();
+        Future<Integer> readResult = client.read(buffer);
+        while (!readResult.isDone()) {
+
+        }
+        String echo = new String(buffer.array()).trim();
+        buffer.clear();
+        return echo;
+    }
+
+    public void stop() {
+        try {
+            client.close();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        AsyncEchoClient client = AsyncEchoClient.getInstance();
+        client.start();
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        String line = null;
+        System.out.println("Message to server:");
+        while ((line = br.readLine()) != null) {
+            String response = client.sendMessage(line);
+            System.out.println("response from server: " + response);
+            System.out.println("Message to server:");
+        }
+    }
+
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoServer.java

@@ -0,0 +1,79 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+public class AsyncEchoServer {
+    private AsynchronousServerSocketChannel serverChannel;
+    private Future<AsynchronousSocketChannel> acceptResult;
+    private AsynchronousSocketChannel clientChannel;
+
+    public AsyncEchoServer() {
+        try {
+            serverChannel = AsynchronousServerSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            serverChannel.bind(hostAddress);
+            acceptResult = serverChannel.accept();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void runServer() {
+        try {
+            clientChannel = acceptResult.get();
+            if ((clientChannel != null) && (clientChannel.isOpen())) {
+                while (true) {
+
+                    ByteBuffer buffer = ByteBuffer.allocate(32);
+                    Future<Integer> readResult = clientChannel.read(buffer);
+
+                    while (!readResult.isDone()) {
+                        // do nothing
+                    }
+
+                    buffer.flip();
+                    String message = new String(buffer.array()).trim();
+                    if (message.equals("bye")) {
+                        break; // while loop
+                    }
+                    buffer = ByteBuffer.wrap(new String(message).getBytes());
+                    Future<Integer> writeResult = clientChannel.write(buffer);
+                    while (!writeResult.isDone()) {
+                        // do nothing
+                    }
+                    buffer.clear();
+
+                } // while()
+
+                clientChannel.close();
+                serverChannel.close();
+
+            }
+        } catch (InterruptedException | ExecutionException | IOException e) {
+            e.printStackTrace();
+        }
+
+    }
+
+    public static void main(String[] args) {
+        AsyncEchoServer server = new AsyncEchoServer();
+        server.runServer();
+    }
+    public static Process start() throws IOException, InterruptedException {
+        String javaHome = System.getProperty("java.home");
+        String javaBin = javaHome + File.separator + "bin" + File.separator + "java";
+        String classpath = System.getProperty("java.class.path");
+        String className = AsyncEchoServer.class.getCanonicalName();
+
+        ProcessBuilder builder = new ProcessBuilder(javaBin, "-cp", classpath, className);
+
+        return builder.start();
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoServer2.java

@@ -0,0 +1,100 @@
+package com.baeldung.java.nio2.async;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousServerSocketChannel;
+import java.nio.channels.AsynchronousSocketChannel;
+import java.nio.channels.CompletionHandler;
+import java.util.HashMap;
+import java.util.Map;
+
+public class AsyncEchoServer2 {
+    private AsynchronousServerSocketChannel serverChannel;
+    private AsynchronousSocketChannel clientChannel;
+
+    public AsyncEchoServer2() {
+        try {
+            serverChannel = AsynchronousServerSocketChannel.open();
+            InetSocketAddress hostAddress = new InetSocketAddress("localhost", 4999);
+            serverChannel.bind(hostAddress);
+            while (true) {
+
+                serverChannel.accept(null, new CompletionHandler<AsynchronousSocketChannel, Object>() {
+
+                    @Override
+                    public void completed(AsynchronousSocketChannel result, Object attachment) {
+                        if (serverChannel.isOpen())
+                            serverChannel.accept(null, this);
+                        clientChannel = result;
+                        if ((clientChannel != null) && (clientChannel.isOpen())) {
+                            ReadWriteHandler handler = new ReadWriteHandler();
+                            ByteBuffer buffer = ByteBuffer.allocate(32);
+                            Map<String, Object> readInfo = new HashMap<>();
+                            readInfo.put("action", "read");
+                            readInfo.put("buffer", buffer);
+                            clientChannel.read(buffer, readInfo, handler);
+                        }
+                    }
+
+                    @Override
+                    public void failed(Throwable exc, Object attachment) {
+                        // process error
+                    }
+                });
+                try {
+                    System.in.read();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+    }
+
+    class ReadWriteHandler implements CompletionHandler<Integer, Map<String, Object>> {
+
+        @Override
+        public void completed(Integer result, Map<String, Object> attachment) {
+            Map<String, Object> actionInfo = attachment;
+            String action = (String) actionInfo.get("action");
+            if ("read".equals(action)) {
+                ByteBuffer buffer = (ByteBuffer) actionInfo.get("buffer");
+                buffer.flip();
+                actionInfo.put("action", "write");
+                clientChannel.write(buffer, actionInfo, this);
+                buffer.clear();
+            } else if ("write".equals(action)) {
+                ByteBuffer buffer = ByteBuffer.allocate(32);
+                actionInfo.put("action", "read");
+                actionInfo.put("buffer", buffer);
+                clientChannel.read(buffer, actionInfo, this);
+            }
+
+        }
+
+        @Override
+        public void failed(Throwable exc, Map<String, Object> attachment) {
+
+        }
+
+    }
+
+
+    public static void main(String[] args) {
+        new AsyncEchoServer2();
+    }
+
+    public static Process start() throws IOException, InterruptedException {
+        String javaHome = System.getProperty("java.home");
+        String javaBin = javaHome + File.separator + "bin" + File.separator + "java";
+        String classpath = System.getProperty("java.class.path");
+        String className = AsyncEchoServer2.class.getCanonicalName();
+
+        ProcessBuilder builder = new ProcessBuilder(javaBin, "-cp", classpath, className);
+
+        return builder.start();
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncEchoTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.java.nio2.async;
+
+import static org.junit.Assert.*;
+
+import java.io.IOException;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+public class AsyncEchoTest {
+
+    Process server;
+    AsyncEchoClient client;
+
+    @Before
+    public void setup() throws IOException, InterruptedException {
+        server = AsyncEchoServer2.start();
+        client = AsyncEchoClient.getInstance();
+    }
+
+    @Test
+    public void givenServerClient_whenServerEchosMessage_thenCorrect() {
+        String resp1 = client.sendMessage("hello");
+        String resp2 = client.sendMessage("world");
+        assertEquals("hello", resp1);
+        assertEquals("world", resp2);
+    }
+
+    @After
+    public void teardown() throws IOException {
+        server.destroy();
+        client.stop();
+    }
+
+}

core-java/src/test/java/com/baeldung/java/nio2/async/AsyncFileTest.java

@@ -0,0 +1,130 @@
+package com.baeldung.java.nio2.async;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.net.URI;
+import java.nio.ByteBuffer;
+import java.nio.channels.AsynchronousFileChannel;
+import java.nio.channels.CompletionHandler;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
+import java.util.UUID;
+import java.util.concurrent.Future;
+
+import org.junit.Test;
+
+public class AsyncFileTest {
+    @Test
+    public void givenPath_whenReadsContentWithFuture_thenCorrect() throws IOException {
+        Path path = Paths.get(URI.create(new AsyncFileTest().getClass().getResource("/file.txt").toString()));
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        Future<Integer> operation = fileChannel.read(buffer, 0);
+
+        while (!operation.isDone())
+            ;
+
+        String fileContent = new String(buffer.array()).trim();
+        buffer.clear();
+
+        assertEquals(fileContent, "baeldung.com");
+    }
+
+    @Test
+    public void givenPath_whenReadsContentWithCompletionHandler_thenCorrect() throws IOException {
+        Path path = Paths.get(URI.create(new AsyncFileTest().getClass().getResource("/file.txt").toString()));
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        fileChannel.read(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {
+
+            @Override
+            public void completed(Integer result, ByteBuffer attachment) {
+                // result is number of bytes read
+                // attachment is the buffer
+
+            }
+
+            @Override
+            public void failed(Throwable exc, ByteBuffer attachment) {
+
+            }
+        });
+    }
+
+    @Test
+    public void givenPathAndContent_whenWritesToFileWithFuture_thenCorrect() throws IOException {
+        String fileName = UUID.randomUUID().toString();
+        Path path = Paths.get(fileName);
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE,StandardOpenOption.DELETE_ON_CLOSE);
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+        long position = 0;
+
+        buffer.put("hello world".getBytes());
+        buffer.flip();
+
+        Future<Integer> operation = fileChannel.write(buffer, position);
+        buffer.clear();
+
+        while (!operation.isDone()) {
+
+        }
+
+        String content = readContent(path);
+        assertEquals("hello world", content);
+    }
+
+    @Test
+    public void givenPathAndContent_whenWritesToFileWithHandler_thenCorrect() throws IOException {
+        String fileName = UUID.randomUUID().toString();
+        Path path = Paths.get(fileName);
+        AsynchronousFileChannel fileChannel = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE, StandardOpenOption.CREATE,StandardOpenOption.DELETE_ON_CLOSE);
+
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+        buffer.put("hello world".getBytes());
+        buffer.flip();
+
+        fileChannel.write(buffer, 0, buffer, new CompletionHandler<Integer, ByteBuffer>() {
+
+            @Override
+            public void completed(Integer result, ByteBuffer attachment) {
+                // result is number of bytes written
+                // attachment is the buffer
+
+            }
+
+            @Override
+            public void failed(Throwable exc, ByteBuffer attachment) {
+
+            }
+        });
+    }
+
+    public static String readContent(Path file) {
+        AsynchronousFileChannel fileChannel = null;
+        try {
+            fileChannel = AsynchronousFileChannel.open(file, StandardOpenOption.READ);
+        } catch (IOException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+        }
+
+        ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+        Future<Integer> operation = fileChannel.read(buffer, 0);
+
+        while (!operation.isDone())
+            ;
+
+        String fileContent = new String(buffer.array()).trim();
+        buffer.clear();
+        return fileContent;
+    }
+}

core-java/src/test/java/com/baeldung/java/nio2/attributes/BasicAttribsTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.java.nio2.attributes;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.BasicFileAttributeView;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.nio.file.attribute.FileTime;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class BasicAttribsTest {
+    private static final String HOME = System.getProperty("user.home");
+    BasicFileAttributes basicAttribs;
+
+    @Before
+    public void setup() throws IOException {
+        Path home = Paths.get(HOME);
+        BasicFileAttributeView basicView = Files.getFileAttributeView(home, BasicFileAttributeView.class);
+        basicAttribs = basicView.readAttributes();
+    }
+
+    @Test
+    public void givenFileTimes_whenComparesThem_ThenCorrect() {
+        FileTime created = basicAttribs.creationTime();
+        FileTime modified = basicAttribs.lastModifiedTime();
+        FileTime accessed = basicAttribs.lastAccessTime();
+
+        assertTrue(0 > created.compareTo(accessed));
+        assertTrue(0 < modified.compareTo(created));
+        assertTrue(0 == created.compareTo(created));
+    }
+
+    @Test
+    public void givenPath_whenGetsFileSize_thenCorrect() {
+        long size = basicAttribs.size();
+        assertTrue(size > 0);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfDirectory_thenCorrect() {
+        boolean isDir = basicAttribs.isDirectory();
+        assertTrue(isDir);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfFile_thenCorrect() {
+        boolean isFile = basicAttribs.isRegularFile();
+        assertFalse(isFile);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfSymLink_thenCorrect() {
+        boolean isSymLink = basicAttribs.isSymbolicLink();
+        assertFalse(isSymLink);
+    }
+
+    @Test
+    public void givenPath_whenChecksIfOther_thenCorrect() {
+        boolean isOther = basicAttribs.isOther();
+        assertFalse(isOther);
+    }
+}