BAEL-3091: The Prototype Pattern in Java (changed code based on valid comments from a reader)

undertow/README.md

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+## Undertow
+
+This module contains articles about JBoss Undertow
+
+### Relevant Articles:
+- [Introduction to JBoss Undertow](https://www.baeldung.com/jboss-undertow)

undertow/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.undertow</groupId>
+    <artifactId>undertow</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>undertow</name>
+    <packaging>jar</packaging>
+    <url>http://maven.apache.org</url>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.undertow</groupId>
+            <artifactId>undertow-servlet</artifactId>
+            <version>${undertow-servlet.version}</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>${project.artifactId}</finalName>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-shade-plugin</artifactId>
+                <version>${maven-shade-plugin.version}</version>
+                <executions>
+                    <execution>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>shade</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>${maven-jar-plugin.version}</version>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <mainClass>com.baeldung.undertow.SimpleServer</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <properties>
+        <undertow-servlet.version>1.4.18.Final</undertow-servlet.version>
+        <maven-shade-plugin.version>2.4.3</maven-shade-plugin.version>
+        <maven-jar-plugin.version>3.0.2</maven-jar-plugin.version>
+    </properties>
+
+</project>

undertow/src/main/java/com/baeldung/undertow/SimpleServer.java

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+package com.baeldung.undertow;
+
+import io.undertow.Undertow;
+import io.undertow.util.Headers;
+
+public class SimpleServer {
+
+    public static void main(String[] args) {
+        Undertow server = Undertow.builder().addHttpListener(8080, "localhost").setHandler(exchange -> {
+            exchange.getResponseHeaders().put(Headers.CONTENT_TYPE, "text/plain");
+            exchange.getResponseSender().send("Hello Baeldung");
+        }).build();
+        server.start();
+    }
+
+}

undertow/src/main/java/com/baeldung/undertow/ftp/FileServer.java

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+package com.baeldung.undertow.ftp;
+
+import io.undertow.Undertow;
+import io.undertow.server.handlers.resource.PathResourceManager;
+
+import java.nio.file.Paths;
+
+import static io.undertow.Handlers.resource;
+
+public class FileServer {
+
+    public static void main(String[] args) {
+        Undertow server = Undertow.builder().addHttpListener(8080, "localhost")
+          .setHandler(resource(new PathResourceManager(Paths.get(System.getProperty("user.home")), 100))
+            .setDirectoryListingEnabled(true))
+          .build();
+        server.start();
+    }
+
+}

undertow/src/main/java/com/baeldung/undertow/secure/CustomIdentityManager.java

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+package com.baeldung.undertow.secure;
+
+import java.security.Principal;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+
+import io.undertow.security.idm.Account;
+import io.undertow.security.idm.Credential;
+import io.undertow.security.idm.IdentityManager;
+import io.undertow.security.idm.PasswordCredential;
+
+public class CustomIdentityManager implements IdentityManager {
+
+    private final Map<String, char[]> users;
+
+    CustomIdentityManager(final Map<String, char[]> users) {
+        this.users = users;
+    }
+
+    @Override
+    public Account verify(Account account) {
+        return account;
+    }
+
+    @Override
+    public Account verify(Credential credential) {
+        return null;
+    }
+
+    @Override
+    public Account verify(String id, Credential credential) {
+        Account account = getAccount(id);
+        if (account != null && verifyCredential(account, credential)) {
+            return account;
+        }
+        return null;
+    }
+
+    private boolean verifyCredential(Account account, Credential credential) {
+        if (credential instanceof PasswordCredential) {
+            char[] password = ((PasswordCredential) credential).getPassword();
+            char[] expectedPassword = users.get(account.getPrincipal().getName());
+
+            return Arrays.equals(password, expectedPassword);
+        }
+        return false;
+    }
+
+    private Account getAccount(final String id) {
+        if (users.containsKey(id)) {
+            return new Account() {
+
+                private static final long serialVersionUID = 1L;
+
+                private final Principal principal = () -> id;
+
+                @Override
+                public Principal getPrincipal() {
+                    return principal;
+                }
+
+                @Override
+                public Set<String> getRoles() {
+                    return Collections.emptySet();
+                }
+            };
+        }
+        return null;
+    }
+
+}

undertow/src/main/java/com/baeldung/undertow/secure/SecureServer.java

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+package com.baeldung.undertow.secure;
+
+import io.undertow.Undertow;
+import io.undertow.io.IoCallback;
+import io.undertow.security.api.AuthenticationMechanism;
+import io.undertow.security.api.AuthenticationMode;
+import io.undertow.security.api.SecurityContext;
+import io.undertow.security.handlers.AuthenticationCallHandler;
+import io.undertow.security.handlers.AuthenticationConstraintHandler;
+import io.undertow.security.handlers.AuthenticationMechanismsHandler;
+import io.undertow.security.handlers.SecurityInitialHandler;
+import io.undertow.security.idm.IdentityManager;
+import io.undertow.security.impl.BasicAuthenticationMechanism;
+import io.undertow.server.HttpHandler;
+import io.undertow.server.HttpServerExchange;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class SecureServer {
+
+    public static void main(String[] args) {
+        final Map<String, char[]> users = new HashMap<>(2);
+        users.put("root", "password".toCharArray());
+        users.put("admin", "password".toCharArray());
+
+        final IdentityManager idm = new CustomIdentityManager(users);
+
+        Undertow server = Undertow.builder()
+          .addHttpListener(8080, "localhost")
+          .setHandler(addSecurity(SecureServer::setExchange, idm)).build();
+
+        server.start();
+    }
+
+    private static void setExchange(HttpServerExchange exchange) {
+        final SecurityContext context = exchange.getSecurityContext();
+        exchange.getResponseSender().send("Hello " + context.getAuthenticatedAccount().getPrincipal().getName(), IoCallback.END_EXCHANGE);
+    }
+
+    private static HttpHandler addSecurity(final HttpHandler toWrap, final IdentityManager identityManager) {
+        HttpHandler handler = toWrap;
+        handler = new AuthenticationCallHandler(handler);
+        handler = new AuthenticationConstraintHandler(handler);
+        final List<AuthenticationMechanism> mechanisms = Collections
+          .singletonList(new BasicAuthenticationMechanism("Baeldung_Realm"));
+        handler = new AuthenticationMechanismsHandler(handler, mechanisms);
+        handler = new SecurityInitialHandler(AuthenticationMode.PRO_ACTIVE, identityManager, handler);
+        return handler;
+    }
+
+}

undertow/src/main/java/com/baeldung/undertow/socket/SocketServer.java

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+package com.baeldung.undertow.socket;
+
+import io.undertow.Undertow;
+import io.undertow.server.handlers.resource.ClassPathResourceManager;
+import io.undertow.websockets.core.AbstractReceiveListener;
+import io.undertow.websockets.core.BufferedTextMessage;
+import io.undertow.websockets.core.WebSocketChannel;
+import io.undertow.websockets.core.WebSockets;
+
+import static io.undertow.Handlers.path;
+import static io.undertow.Handlers.resource;
+import static io.undertow.Handlers.websocket;
+
+public class SocketServer {
+
+    public static void main(String[] args) {
+        Undertow server = Undertow.builder().addHttpListener(8080, "localhost")
+                .setHandler(path().addPrefixPath("/baeldungApp", websocket((exchange, channel) -> {
+                    channel.getReceiveSetter().set(getListener());
+                    channel.resumeReceives();
+                })).addPrefixPath("/", resource(new ClassPathResourceManager(SocketServer.class.getClassLoader(),
+                        SocketServer.class.getPackage())).addWelcomeFiles("index.html")))
+                .build();
+
+        server.start();
+    }
+
+    private static AbstractReceiveListener getListener() {
+        return new AbstractReceiveListener() {
+            @Override
+            protected void onFullTextMessage(WebSocketChannel channel, BufferedTextMessage message) {
+                final String messageData = message.getData();
+                for (WebSocketChannel session : channel.getPeerConnections()) {
+                    WebSockets.sendText(messageData, session, null);
+                }
+            }
+        };
+    }
+    
+}

undertow/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>