BAEL-6254: Scoped values (#13756)

core-java-modules/core-java-20/README.md

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+## Relevant Articles
+- TBD

core-java-modules/core-java-20/pom.xml

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+<?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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <parent>
+        <groupId>com.baeldung.core-java-modules</groupId>
+        <artifactId>core-java-modules</artifactId>
+        <version>0.0.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>core-java-20</artifactId>
+
+    <properties>
+        <maven.compiler.source>20</maven.compiler.source>
+        <maven.compiler.target>20</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-compiler-plugin</artifactId>
+                <configuration>
+                    <source>20</source>
+                    <target>20</target>
+                    <compilerArgs>
+                        <arg>--enable-preview</arg>
+                        <arg>--add-modules=jdk.incubator.concurrent</arg>
+                    </compilerArgs>
+                </configuration>
+            </plugin>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <configuration>
+                    <argLine>--enable-preview --add-modules=jdk.incubator.concurrent</argLine>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>jakarta.servlet</groupId>
+            <artifactId>jakarta.servlet-api</artifactId>
+            <version>6.0.0</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.24.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-junit-jupiter</artifactId>
+            <version>5.2.0</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+</project>

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/classic/Controller.java

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+package com.baeldung.scopedvalues.classic;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Optional;
+
+public class Controller {
+
+    private final Service service = new Service();
+
+    public void processRequest(HttpServletRequest request, HttpServletResponse response, User loggedInUser) {
+        Optional<Data> data = service.getData(request, loggedInUser);
+        if (data.isPresent()) {
+            try {
+                PrintWriter out = response.getWriter();
+                response.setContentType("application/json");
+                out.print(data.get());
+                out.flush();
+                response.setStatus(200);
+            } catch (IOException e) {
+                response.setStatus(500);
+            }
+        } else {
+            response.setStatus(400);
+        }
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/classic/Repository.java

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+package com.baeldung.scopedvalues.classic;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+
+import java.util.Optional;
+
+public class Repository {
+
+    public Optional<Data> getData(String id, User user) {
+        return user.isAdmin()
+                ? Optional.of(new Data(id, "Title 1", "Description 1"))
+                : Optional.empty();
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/classic/Server.java

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+package com.baeldung.scopedvalues.classic;
+
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.*;
+
+public class Server {
+
+    private static final List<User> AUTHENTICATED_USERS = List.of(
+            new User("1", "admin", "123456", true),
+            new User("2", "user", "123456", false)
+    );
+    private final Controller controller = new Controller();
+    private final ExecutorService executor = Executors.newFixedThreadPool(5);
+
+    public void serve(HttpServletRequest request, HttpServletResponse response) throws InterruptedException, ExecutionException {
+        Optional<User> user = authenticateUser(request);
+        if (user.isPresent()) {
+            Future<?> future = executor.submit(() ->
+                    controller.processRequest(request, response, user.get()));
+            future.get();
+        } else {
+            response.setStatus(401);
+        }
+    }
+
+    private Optional<User> authenticateUser(HttpServletRequest request) {
+        return AUTHENTICATED_USERS.stream()
+                .filter(user -> checkUserPassword(user, request))
+                .findFirst();
+    }
+
+    private boolean checkUserPassword(User user, HttpServletRequest request) {
+        return user.name().equals(request.getParameter("user_name"))
+                && user.password().equals(request.getParameter("user_pw"));
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/classic/Service.java

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+package com.baeldung.scopedvalues.classic;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+
+import java.util.Optional;
+
+public class Service {
+
+    private final Repository repository = new Repository();
+
+    public Optional<Data> getData(HttpServletRequest request, User loggedInUser) {
+        String id = request.getParameter("data_id");
+        return repository.getData(id, loggedInUser);
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/data/Data.java

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+package com.baeldung.scopedvalues.data;
+
+public record Data(String id, String title, String description) {}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/data/User.java

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+package com.baeldung.scopedvalues.data;
+
+public record User(String id, String name, String password, boolean isAdmin) {}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/Controller.java

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+package com.baeldung.scopedvalues.scoped;
+
+import com.baeldung.scopedvalues.data.Data;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jdk.incubator.concurrent.ScopedValue;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Optional;
+
+public class Controller {
+
+    private final Service internalService = new Service();
+
+    public void processRequest(HttpServletRequest request, HttpServletResponse response) {
+        Optional<Data> data = internalService.getData(request);
+
+        ScopedValue.where(Server.LOGGED_IN_USER, null)
+                .run(internalService::extractData);
+
+        if (data.isPresent()) {
+            try {
+                PrintWriter out = response.getWriter();
+                response.setContentType("application/json");
+                out.print(data.get());
+                out.flush();
+                response.setStatus(200);
+            } catch (IOException e) {
+                response.setStatus(500);
+            }
+        } else {
+            response.setStatus(400);
+        }
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/Repository.java

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+package com.baeldung.scopedvalues.scoped;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+
+import java.util.Optional;
+
+public class Repository {
+
+    public Optional<Data> getData(String id) {
+        User loggedInUser = Server.LOGGED_IN_USER.get();
+        return loggedInUser.isAdmin()
+                ? Optional.of(new Data(id, "Title 1", "Description 1"))
+                : Optional.empty();
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/Server.java

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+package com.baeldung.scopedvalues.scoped;
+
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jdk.incubator.concurrent.ScopedValue;
+
+import java.util.List;
+import java.util.Optional;
+
+public class Server {
+
+    private static final List<User> AUTHENTICATED_USERS = List.of(
+            new User("1", "admin", "123456", true),
+            new User("2", "user", "123456", false)
+    );
+    public final static ScopedValue<User> LOGGED_IN_USER = ScopedValue.newInstance();
+    private final Controller controller = new Controller();
+
+    public void serve(HttpServletRequest request, HttpServletResponse response) {
+        Optional<User> user = authenticateUser(request);
+        if (user.isPresent()) {
+            ScopedValue.where(LOGGED_IN_USER, user.get())
+                    .run(() -> controller.processRequest(request, response));
+        } else {
+            response.setStatus(401);
+        }
+    }
+
+    private Optional<User> authenticateUser(HttpServletRequest request) {
+        return AUTHENTICATED_USERS.stream()
+                .filter(user -> checkUserPassword(user, request))
+                .findFirst();
+    }
+
+    private boolean checkUserPassword(User user, HttpServletRequest request) {
+        return user.name().equals(request.getParameter("user_name"))
+                && user.password().equals(request.getParameter("user_pw"));
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/Service.java

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+package com.baeldung.scopedvalues.scoped;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+
+import java.util.Optional;
+
+public class Service {
+
+    private final Repository repository = new Repository();
+
+    public Optional<Data> getData(HttpServletRequest request) {
+        String id = request.getParameter("data_id");
+        return repository.getData(id);
+    }
+
+    public void extractData() {
+        User loggedInUser = Server.LOGGED_IN_USER.get();
+        assert loggedInUser == null;
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/inheriting/Controller.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+import com.baeldung.scopedvalues.data.Data;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jdk.incubator.concurrent.StructuredTaskScope;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.Optional;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+public class Controller {
+
+    private final InternalService internalService = new InternalService();
+    private final ExternalService externalService = new ExternalService();
+
+    public void processRequest(HttpServletRequest request, HttpServletResponse response) {
+        try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
+            Future<Optional<Data>> internalData = scope.fork(() -> internalService.getData(request));
+            Future<String> externalData = scope.fork(externalService::getData);
+            try {
+                scope.join();
+                scope.throwIfFailed();
+
+                Optional<Data> data = internalData.resultNow();
+                if (data.isPresent()) {
+                    PrintWriter out = response.getWriter();
+                    response.setContentType("application/json");
+                    out.println(data.get());
+                    out.print(externalData.resultNow());
+                    out.flush();
+                    response.setStatus(200);
+                } else {
+                    response.setStatus(400);
+                }
+            } catch (InterruptedException | ExecutionException | IOException e) {
+                response.setStatus(500);
+            }
+        }
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/inheriting/ExternalService.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+public class ExternalService {
+
+    public String getData() {
+        return "External data";
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/inheriting/InternalService.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+import com.baeldung.scopedvalues.data.Data;
+import jakarta.servlet.http.HttpServletRequest;
+
+import java.util.Optional;
+
+public class InternalService {
+
+    private final Repository repository = new Repository();
+
+    public Optional<Data> getData(HttpServletRequest request) {
+        String id = request.getParameter("data_id");
+        return repository.getData(id);
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/inheriting/Repository.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+import com.baeldung.scopedvalues.data.Data;
+import com.baeldung.scopedvalues.data.User;
+
+import java.util.Optional;
+
+public class Repository {
+
+    public Optional<Data> getData(String id) {
+        User loggedInUser = Server.LOGGED_IN_USER.get();
+        return loggedInUser.isAdmin()
+                ? Optional.of(new Data(id, "Title 1", "Description 1"))
+                : Optional.empty();
+    }
+
+}

core-java-modules/core-java-20/src/main/java/com/baeldung/scopedvalues/scoped/inheriting/Server.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+import com.baeldung.scopedvalues.data.User;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import jdk.incubator.concurrent.ScopedValue;
+
+import java.util.List;
+import java.util.Optional;
+
+public class Server {
+
+    private static final List<User> AUTHENTICATED_USERS = List.of(
+            new User("1", "admin", "123456", true),
+            new User("2", "user", "123456", false)
+    );
+    public final static ScopedValue<User> LOGGED_IN_USER = ScopedValue.newInstance();
+    private final Controller controller = new Controller();
+
+    public void serve(HttpServletRequest request, HttpServletResponse response) {
+        Optional<User> user = authenticateUser(request);
+        if (user.isPresent()) {
+            ScopedValue.where(LOGGED_IN_USER, user.get())
+                    .run(() -> controller.processRequest(request, response));
+        } else {
+            response.setStatus(401);
+        }
+    }
+
+    private Optional<User> authenticateUser(HttpServletRequest request) {
+        return AUTHENTICATED_USERS.stream()
+                .filter(user -> checkUserPassword(user, request))
+                .findFirst();
+    }
+
+    private boolean checkUserPassword(User user, HttpServletRequest request) {
+        return user.name().equals(request.getParameter("user_name"))
+                && user.password().equals(request.getParameter("user_pw"));
+    }
+
+}

core-java-modules/core-java-20/src/test/java/com/baeldung/scopedvalues/classic/ServerUnitTest.java

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+package com.baeldung.scopedvalues.classic;
+
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.util.concurrent.ExecutionException;
+
+import static org.mockito.Mockito.*;
+import static org.assertj.core.api.Assertions.*;
+@ExtendWith(MockitoExtension.class)
+public class ServerUnitTest {
+
+    @Mock
+    private HttpServletRequest request;
+
+    @Mock
+    private HttpServletResponse response;
+
+    private final StringWriter writer = new StringWriter();
+
+    private final Server server = new Server();
+
+    @Test
+    void givenMockedRequestWithAdminCredentials_whenServeMethodIsCalled_thenDataIsReturned() throws InterruptedException, IOException, ExecutionException {
+        when(request.getParameter("user_name")).thenReturn("admin");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+        when(request.getParameter("data_id")).thenReturn("1");
+        when(response.getWriter()).thenReturn(new PrintWriter(writer));
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("Data[id=1, title=Title 1, description=Description 1]");
+    }
+
+    @Test
+    void givenMockedRequestWithUserCredentials_whenServeMethodIsCalled_thenNoDataIsReturned() throws InterruptedException, ExecutionException {
+        when(request.getParameter("user_name")).thenReturn("user");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("");
+    }
+
+}

core-java-modules/core-java-20/src/test/java/com/baeldung/scopedvalues/scoped/ServerUnitTest.java

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+package com.baeldung.scopedvalues.scoped;
+
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+public class ServerUnitTest {
+
+    @Mock
+    private HttpServletRequest request;
+
+    @Mock
+    private HttpServletResponse response;
+
+    private final StringWriter writer = new StringWriter();
+
+    private final Server server = new Server();
+
+    @Test
+    void givenMockedRequestWithAdminCredentials_whenServeMethodIsCalled_thenDataIsReturned() throws IOException {
+        when(request.getParameter("user_name")).thenReturn("admin");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+        when(request.getParameter("data_id")).thenReturn("1");
+        when(response.getWriter()).thenReturn(new PrintWriter(writer));
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("Data[id=1, title=Title 1, description=Description 1]");
+    }
+
+    @Test
+    void givenMockedRequestWithUserCredentials_whenServeMethodIsCalled_thenNoDataIsReturned() throws IOException {
+        when(request.getParameter("user_name")).thenReturn("user");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("");
+    }
+
+}

core-java-modules/core-java-20/src/test/java/com/baeldung/scopedvalues/scoped/inheriting/ServerUnitTest.java

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+package com.baeldung.scopedvalues.scoped.inheriting;
+
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.io.StringWriter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+public class ServerUnitTest {
+
+    @Mock
+    private HttpServletRequest request;
+
+    @Mock
+    private HttpServletResponse response;
+
+    private final StringWriter writer = new StringWriter();
+
+    private final Server server = new Server();
+
+    @Test
+    void givenMockedRequestWithAdminCredentials_whenServeMethodIsCalled_thenDataIsReturned() throws IOException {
+        when(request.getParameter("user_name")).thenReturn("admin");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+        when(request.getParameter("data_id")).thenReturn("1");
+        when(response.getWriter()).thenReturn(new PrintWriter(writer));
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("Data[id=1, title=Title 1, description=Description 1]\nExternal data");
+    }
+
+    @Test
+    void givenMockedRequestWithUserCredentials_whenServeMethodIsCalled_thenNoDataIsReturned() throws IOException {
+        when(request.getParameter("user_name")).thenReturn("user");
+        when(request.getParameter("user_pw")).thenReturn("123456");
+
+        server.serve(request, response);
+
+        assertThat(writer.toString()).isEqualTo("");
+    }
+
+}