[BAEL-3601] - Fix code review comments.

2020-02-09 00:49:26 -05:00
parent e94f0ad2f1
commit 696e4943df
14 changed files with 156 additions and 520 deletions
@@ -8,5 +8,4 @@ This module contains articles about core Java non-blocking input and output (IO)
 - [Create a Symbolic Link with Java](https://www.baeldung.com/java-symlink)
 - [Introduction to the Java NIO Selector](https://www.baeldung.com/java-nio-selector)
 - [Using Java MappedByteBuffer](https://www.baeldung.com/java-mapped-byte-buffer)
- [How to Lock a File in Java](https://www.baeldung.com/how-to-lock-a-file-in-java)
+- [[<-- Prev]](/core-java-modules/core-java-nio)
 - [[<-- Prev]](/core-java-modules/core-java-nio)
@@ -1,87 +0,0 @@
 package com.baeldung.lock;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import java.io.IOException;
 import java.nio.channels.FileLock;
 import java.nio.channels.NonReadableChannelException;
 import java.nio.channels.NonWritableChannelException;
 import org.junit.jupiter.api.Test;
 class FileLocksTest {
 	// Exclusive locks
 	/**
 	 * Getting an exclusive (write) lock on the entire file.
 	 * Fails when getting the lock from a FileChannel obtained through a FileInputStream.
 	 */
 	@Test
 	void givenAnInputStream_whenGetWriteLock_throwNonWritableChannelException() {
 		assertThrows(NonWritableChannelException.class, 
 				() -> FileLocks.getExclusiveLockFromInputStream());
 	}
 	/**
 	 * Getting an exclusive lock from a RandomAccessFile
 	 * @throws IOException
 	 */
 	@Test
 	void givenARandomAccessFileWithReadWriteAccess_whenGetWriteLock_lock() throws IOException {
 		FileLock lock = FileLocks.getExclusiveLockFromRandomAccessFile(0, 10);
 		assertNotNull(lock);
 		assertFalse(lock.isShared());
 	}
 	/**
 	 * Getting an exclusive lock from FileChannel::open
 	 * @throws IOException
 	 */
 	@Test
 	void givenAPath_whenGetExclusiveLock_lock() throws IOException {
 		FileLock lock = FileLocks.getExclusiveLockFromFileChannelOpen(0, 10);
 		assertNotNull(lock);
 		assertFalse(lock.isShared());
 	}
 	// Shared locks
 	/**
 	 * Getting a shared (read) lock on the entire file.
 	 * Fails when getting the lock from a FileChannel obtained through a FileOutputStream.
 	 */
 	@Test
 	void givenAFileOutputStream_whenGetSharedLock_throwNonReadableChannelException() {
 		assertThrows(NonReadableChannelException.class, 
 				() -> FileLocks.getReadLockFromOutputStream(0, 10));
 	}
 	/**
 	 * Getting a shared (read) lock works fine when getting the lock from a FileChannel obtained through a FileInputStream.
 	 * @throws IOException
 	 */
 	@Test
 	void givenAnInputStream_whenGetSharedLock_lock() throws IOException {
 		FileLock lock = FileLocks.getReadLockFromInputStream(0, 10);
 		assertNotNull(lock);
 		assertTrue(lock.isShared());
 	}
 	/**
 	 * Getting a shared lock from a RandomAccessFile
 	 * @throws IOException
 	 */
 	@Test
 	void givenARandomAccessFile_whenGetSharedLock_lock() throws IOException {
 		FileLock lock = FileLocks.getReadLockFromRandomAccessFile(0,  10);
 		assertNotNull(lock);
 		assertTrue(lock.isShared());
 	}
 }
@@ -0,0 +1,48 @@
 package com.baeldung.lock;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import java.io.IOException;
 import java.nio.channels.FileLock;
 import java.nio.channels.NonReadableChannelException;
 import java.nio.channels.NonWritableChannelException;
 import org.junit.jupiter.api.Test;
 class FileLocksUnitTest {
    @Test void givenAnInputStream_whenGetWriteLock_throwNonWritableChannelException() {
        assertThrows(NonWritableChannelException.class, () -> FileLocks.getExclusiveLockFromInputStream());
    }
    @Test void givenARandomAccessFileWithReadWriteAccess_whenGetWriteLock_lock() throws IOException {
        FileLock lock = FileLocks.getExclusiveLockFromRandomAccessFile(0, 10);
        assertNotNull(lock);
        assertFalse(lock.isShared());
    }
    @Test void givenAPath_whenGetExclusiveLock_lock() throws IOException {
        FileLock lock = FileLocks.getExclusiveLockFromFileChannelOpen(0, 10);
        assertNotNull(lock);
        assertFalse(lock.isShared());
    }
    @Test void givenAFileOutputStream_whenGetSharedLock_throwNonReadableChannelException() {
        assertThrows(NonReadableChannelException.class, FileLocks::getReadLockFromOutputStream);
    }
    @Test void givenAnInputStream_whenGetSharedLock_lock() throws IOException {
        FileLock lock = FileLocks.getReadLockFromInputStream(0, 10);
        assertNotNull(lock);
        assertTrue(lock.isShared());
    }
    @Test void givenARandomAccessFile_whenGetSharedLock_lock() throws IOException {
        FileLock lock = FileLocks.getReadLockFromRandomAccessFile(0, 10);
        assertNotNull(lock);
        assertTrue(lock.isShared());
    }
 }
@@ -1,4 +1,3 @@
 ### Relevant Articles:
 - [Service Locator Pattern](https://www.baeldung.com/java-service-locator-pattern)
 - [The DAO Pattern in Java](https://www.baeldung.com/java-dao-pattern)
 - [A Practical Example of Hexagonal Architecture in Java](https://www.baeldung.com/java-hexagonal-pattern)
@@ -1,45 +0,0 @@
 package com.baeldung.hexagonal;
 import com.baeldung.hexagonal.adapters.DisplayInConsoleAdapter;
 import com.baeldung.hexagonal.adapters.InMemoryMessageStore;
 import com.baeldung.hexagonal.application.ChatManager;
 import com.baeldung.hexagonal.domain.ChatUser;
 import com.baeldung.hexagonal.domain.IDisplayMessages;
 import java.util.ArrayDeque;
 import java.util.Scanner;
 public class ChatApplication {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        System.out.print("Enter username of user 1: ");
        ChatUser user1 = new ChatUser(console.nextLine());
        System.out.printf("Enter username of user 2: ");
        ChatUser user2 = new ChatUser(console.nextLine());
        System.out.println("Chat will end when any user uses the word bye in a message.");
        InMemoryMessageStore messageStore = new InMemoryMessageStore(new ArrayDeque<>(10));
        IDisplayMessages messageDisplayer = new DisplayInConsoleAdapter(messageStore);
        ChatManager chatManager = new ChatManager(messageStore, messageDisplayer);
        while (true) {
            System.out.printf("From %s to %s : ", user1, user2);
            String message = console.nextLine();
            if (message.toLowerCase().contains("bye")) {
                chatManager.sendMessage(user1, user2, message);
                System.out.println("Chat recap:");
                messageDisplayer.displayMessages();
                System.exit(0);
            }
            chatManager.sendMessage(user1, user2, message);
            ChatUser temp = user1;
            user1 = user2;
            user2 = temp;
        }
    }
 }
@@ -1,36 +0,0 @@
 package com.baeldung.hexagonal.adapters;
 import com.baeldung.hexagonal.domain.ChatMessage;
 import com.baeldung.hexagonal.domain.IDisplayMessages;
 import com.baeldung.hexagonal.domain.IStoreMessages;
 /**
 * A Utility adapter to display the chat messages in the console
 */
 public class DisplayInConsoleAdapter implements IDisplayMessages {
    IStoreMessages messageStore;
    public DisplayInConsoleAdapter(IStoreMessages messageStore) {
        this.messageStore = messageStore;
    }
    public static void clearScreen() {
        System.out.print("\033[H\033[2J");
        System.out.flush();
    }
    @Override
    public void displayMessages() {
        clearScreen();
        for (ChatMessage message: messageStore.getMessages(10)) {
            System.out.printf(
                "%tF %tT [%s to %s]: %s %n",
                message.getTimeSent(),
                message.getTimeSent(),
                message.getFrom(),
                message.getTo(),
                message.getContents());
        }
    }
 }
@@ -1,37 +0,0 @@
 package com.baeldung.hexagonal.adapters;
 import com.baeldung.hexagonal.domain.ChatMessage;
 import com.baeldung.hexagonal.domain.IStoreMessages;
 import java.util.Collection;
 import java.util.Comparator;
 import java.util.Queue;
 import java.util.stream.Collectors;
 /**
 * We're storing the messages in memory. We could later opt to switch to an implementation that stores messages in a
 * database.
 */
 public class InMemoryMessageStore implements IStoreMessages {
    private Queue<ChatMessage> messages;
    public InMemoryMessageStore(Queue<ChatMessage> messages) {
        this.messages = messages;
    }
    @Override
    public void storeMessage(ChatMessage message) {
        this.messages.add(message);
    }
    @Override
    public Collection<ChatMessage> getMessages(long maxNbMessages) {// @formatter:off
        return messages.stream()
            .sorted((m1, m2) -> m2.getTimeSent().compareTo(m1.getTimeSent()))
            .limit(maxNbMessages)
            .sorted(Comparator.comparing(ChatMessage::getTimeSent))
            .collect(Collectors.toList());
        // @formatter:on
    }
 }
@@ -1,27 +0,0 @@
 package com.baeldung.hexagonal.application;
 import com.baeldung.hexagonal.domain.*;
 import java.time.LocalDateTime;
 public class ChatManager implements ISendMessage {
    // The domain doesn't need to know where messages will be stored
    private IStoreMessages messageStore;
    // The domain doesn't need to know how messages will be displayed
    private IDisplayMessages messageDisplayer;
    public ChatManager(IStoreMessages messageStore, IDisplayMessages displayMessages) {
        this.messageStore = messageStore;
        this.messageDisplayer = displayMessages;
    }
    @Override
    public void sendMessage(ChatUser from, ChatUser to, String message) {
        ChatMessage chatMessage = new ChatMessage(LocalDateTime.now(), from, to, message);
        this.messageStore.storeMessage(chatMessage);
        this.messageDisplayer.displayMessages();
    }
 }
@@ -1,34 +0,0 @@
 package com.baeldung.hexagonal.domain;
 import java.time.LocalDateTime;
 public class ChatMessage {
    private LocalDateTime timeSent;
    private ChatUser from;
    private ChatUser to;
    private String contents;
    public LocalDateTime getTimeSent() {
        return timeSent;
    }
    public ChatUser getFrom() {
        return from;
    }
    public ChatUser getTo() {
        return to;
    }
    public String getContents() {
        return contents;
    }
    public ChatMessage(LocalDateTime timeSent, ChatUser from, ChatUser to, String contents) {
        this.timeSent = timeSent;
        this.from = from;
        this.to = to;
        this.contents = contents;
    }
 }
@@ -1,14 +0,0 @@
 package com.baeldung.hexagonal.domain;
 public class ChatUser {
    private String name;
    public ChatUser(String name) {
        this.name = name;
    }
    @Override
    public String toString() {
        return name;
    }
 }
@@ -1,8 +0,0 @@
 package com.baeldung.hexagonal.domain;
 /**
 * An external system displays the messages sent by users.
 */
 public interface IDisplayMessages {
    void displayMessages();
 }
@@ -1,8 +0,0 @@
 package com.baeldung.hexagonal.domain;
 /**
 * A user sends a message (application's use case)
 */
 public interface ISendMessage {
    void sendMessage(ChatUser from, ChatUser to, String message);
 }
@@ -1,14 +0,0 @@
 package com.baeldung.hexagonal.domain;
 import java.util.Collection;
 /**
 * An external system (infrastructure) stores a message
 */
 public interface IStoreMessages {
    void storeMessage(ChatMessage message);
    Collection<ChatMessage> getMessages(long maxNbMessages);
 }