JNDI und Service-Auflösung

<?xml version="1.0" encoding="UTF-8"?>
        <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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
            <modelVersion>4.0.0</modelVersion>
            <parent>
                <groupId>at.aydin.academy</groupId>
                <artifactId>25jndiserviceresolution-pair</artifactId>
                <version>1.0.0</version>
                <relativePath>../pom.xml</relativePath>
            </parent>
            <artifactId>jndi-legacy</artifactId>
            <packaging>jar</packaging>
            <name>JNDI Legacy</name>

            <dependencies>

<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter</artifactId>
    <scope>test</scope>
</dependency>

            </dependencies>
            <build>
                <plugins>
                    <plugin>
                        <groupId>org.apache.maven.plugins</groupId>
                        <artifactId>maven-compiler-plugin</artifactId>
                    </plugin>

                </plugins>
            </build>
        </project>

package at.aydin.lab.jndi.legacy;

public interface GreetingPort {
    String greet(String name);
}

package at.aydin.lab.jndi.legacy;

public final class GreetingService implements GreetingPort {
    @Override
    public String greet(String name) {
        return "Hallo " + name;
    }
}

package at.aydin.lab.jndi.legacy;

// Design Pattern: Service Locator
// Zweck: Zeigt die versteckte Laufzeitabhängigkeit auf JNDI-Name und Naming-Infrastruktur.
public final class LegacyGreetingUseCase {
    private final JndiServiceLocator locator;
    public LegacyGreetingUseCase(JndiServiceLocator locator) {
        this.locator = locator;
    }

    public String execute(String name) {
        GreetingPort port = locator.resolve("service/greeting", GreetingPort.class);
        return port.greet(name);
    }
}

package at.aydin.lab.jndi.legacy;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

class LegacyGreetingUseCaseTest {
    @Test
    void resolvesTheDependencyByJndiName() throws Exception {
        MemoryContext context = new MemoryContext();
        context.rebind("service/greeting", new GreetingService());
        LegacyGreetingUseCase useCase = new LegacyGreetingUseCase(new JndiServiceLocator(context));
        assertEquals("Hallo Test", useCase.execute("Test"));
    }
}

package at.aydin.lab.jndi.legacy;

import javax.naming.*;

// Design Pattern: Service Locator
// Zweck: Versteckt JNDI-Lookups, behält aber die Laufzeitabhängigkeit von String-Namen.
public final class JndiServiceLocator {
    private final Context context;
    public JndiServiceLocator(Context context) {
        this.context = context;
    }

    public <T> T resolve(String name, Class<T> type) {
        try {
            return type.cast(context.lookup(name));
        } catch (NamingException ex) {
            throw new IllegalStateException(ex);
        }
    }
}

package at.aydin.lab.jndi.legacy;

import javax.naming.*;
import java.util.*;

public final class MemoryContext extends InitialContext {
    private static final Map<String, Object> VALUES = new HashMap<>();
    public MemoryContext() throws NamingException {
        super(true);
    }

    @Override
    public Object lookup(String name) throws NamingException {
        Object value = VALUES.get(name);
        if (value == null) throw new NameNotFoundException(name);
        return value;
    }

    @Override
    public void bind(String name, Object obj) throws NamingException {
        if (VALUES.putIfAbsent(name, obj) != null) throw new NameAlreadyBoundException(name);
    }

    @Override
    public void rebind(String name, Object obj) {
        VALUES.put(name, obj);
    }

    @Override
    public void close() {
    }
}

package at.aydin.lab.jndi.legacy;

import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

class JndiServiceLocatorTest {
    @Test
    void resolvesStringName() throws Exception {
        var c = new MemoryContext();
        c.rebind("service/greeting", "Hallo");
        assertEquals("Hallo", new JndiServiceLocator(c).resolve("service/greeting", String.class));
    }
}