+ + update(customer : Customer) : int
+ + delete(id : int) : int
+ }
+}
+App --> CustomerTableGateway
+CustomerTableGateway --> Customer
+@enduml
diff --git a/table-data-gateway/pom.xml b/table-data-gateway/pom.xml
new file mode 100644
index 000000000000..ddeadfe362d4
--- /dev/null
+++ b/table-data-gateway/pom.xml
@@ -0,0 +1,84 @@
+
+
+
+
+ java-design-patterns
+ com.iluwatar
+ 1.26.0-SNAPSHOT
+
+ 4.0.0
+ table-data-gateway
+
+
+ org.slf4j
+ slf4j-api
+
+
+ ch.qos.logback
+ logback-classic
+
+
+ com.h2database
+ h2
+
+
+ org.junit.jupiter
+ junit-jupiter-api
+ test
+
+
+ org.junit.jupiter
+ junit-jupiter-engine
+ test
+
+
+ org.mockito
+ mockito-core
+ test
+
+
+
+
+
+ org.apache.maven.plugins
+ maven-assembly-plugin
+
+
+
+
+
+ com.iluwatar.tabledatagateway.App
+
+
+
+
+
+
+
+
+
diff --git a/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/App.java b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/App.java
new file mode 100644
index 000000000000..b82774c0688d
--- /dev/null
+++ b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/App.java
@@ -0,0 +1,77 @@
+/*
+ * This project is licensed under the MIT license. Module table-data-gateway uses H2 database licensed under EPL (see epl-1.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.tabledatagateway;
+
+import java.sql.SQLException;
+import javax.sql.DataSource;
+import org.h2.jdbcx.JdbcDataSource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** Table Data Gateway pattern demonstration. */
+public class App {
+
+ private static final Logger LOGGER = LoggerFactory.getLogger(App.class);
+
+ private static final String DB_URL = "jdbc:h2:mem:tabledatagateway;DB_CLOSE_DELAY=-1";
+
+ /**
+ * Program entry point.
+ *
+ * @param args command line args
+ * @throws SQLException if a database operation fails
+ */
+ public static void main(final String[] args) throws SQLException {
+ var dataSource = createDataSource();
+ execute(dataSource, CustomerTableGateway.CREATE_SCHEMA_SQL);
+
+ var gateway = new CustomerTableGateway(dataSource);
+ gateway.insert(new Customer(1, "Alice", "Smith"));
+
+ var found = gateway.findById(1);
+ LOGGER.info("Found customer: {}", found.orElse(null));
+
+ gateway.update(new Customer(1, "Alice", "Jones"));
+ LOGGER.info("Customers: {}", gateway.findAll());
+
+ gateway.delete(1);
+ LOGGER.info("Customers after delete: {}", gateway.findAll());
+
+ execute(dataSource, CustomerTableGateway.DELETE_SCHEMA_SQL);
+ }
+
+ private static DataSource createDataSource() {
+ var dataSource = new JdbcDataSource();
+ dataSource.setURL(DB_URL);
+ return dataSource;
+ }
+
+ private static void execute(final DataSource dataSource, final String sql) throws SQLException {
+ try (var connection = dataSource.getConnection();
+ var statement = connection.createStatement()) {
+ statement.execute(sql);
+ }
+ }
+}
diff --git a/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/Customer.java b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/Customer.java
new file mode 100644
index 000000000000..3bdf40a2f783
--- /dev/null
+++ b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/Customer.java
@@ -0,0 +1,28 @@
+/*
+ * This project is licensed under the MIT license. Module table-data-gateway uses H2 database licensed under EPL (see epl-1.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.tabledatagateway;
+
+/** Immutable representation of a row in the CUSTOMERS table. */
+public record Customer(int id, String firstName, String lastName) {}
diff --git a/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/CustomerTableGateway.java b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/CustomerTableGateway.java
new file mode 100644
index 000000000000..42930a0efda9
--- /dev/null
+++ b/table-data-gateway/src/main/java/com/iluwatar/tabledatagateway/CustomerTableGateway.java
@@ -0,0 +1,171 @@
+/*
+ * This project is licensed under the MIT license. Module table-data-gateway uses H2 database licensed under EPL (see epl-1.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.tabledatagateway;
+
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.Optional;
+import javax.sql.DataSource;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Gateway that encapsulates all SQL operations for the CUSTOMERS table.
+ *
+ * Unlike a Row Data Gateway, one instance of this class can operate on any row in the table.
+ */
+public final class CustomerTableGateway {
+
+ /** SQL statement for creating the schema used by this example. */
+ public static final String CREATE_SCHEMA_SQL =
+ "CREATE TABLE IF NOT EXISTS CUSTOMERS (ID INT PRIMARY KEY, FIRST_NAME VARCHAR(30) "
+ + "NOT NULL, LAST_NAME VARCHAR(30) NOT NULL)";
+
+ /** SQL statement for deleting the schema used by this example. */
+ public static final String DELETE_SCHEMA_SQL = "DROP TABLE IF EXISTS CUSTOMERS";
+
+ private static final Logger LOGGER = LoggerFactory.getLogger(CustomerTableGateway.class);
+
+ private final DataSource dataSource;
+
+ /**
+ * Creates a gateway for the CUSTOMERS table.
+ *
+ * @param dataSource data source used by all gateway operations
+ */
+ public CustomerTableGateway(final DataSource dataSource) {
+ this.dataSource = Objects.requireNonNull(dataSource);
+ }
+
+ /**
+ * Inserts a customer row.
+ *
+ * @param customer customer data to insert
+ * @return number of rows inserted
+ * @throws SQLException if the database operation fails
+ */
+ public int insert(final Customer customer) throws SQLException {
+ Objects.requireNonNull(customer);
+ var sql = "INSERT INTO CUSTOMERS (ID, FIRST_NAME, LAST_NAME) VALUES (?,?,?)";
+ try (var connection = dataSource.getConnection();
+ var preparedStatement = connection.prepareStatement(sql)) {
+ preparedStatement.setInt(1, customer.id());
+ preparedStatement.setString(2, customer.firstName());
+ preparedStatement.setString(3, customer.lastName());
+ var inserted = preparedStatement.executeUpdate();
+ LOGGER.info("Inserted customer with id {}", customer.id());
+ return inserted;
+ }
+ }
+
+ /**
+ * Finds a customer by id.
+ *
+ * @param id customer identifier
+ * @return the customer if a matching row exists, otherwise an empty optional
+ * @throws SQLException if the database operation fails
+ */
+ public Optional findById(final int id) throws SQLException {
+ var sql = "SELECT ID, FIRST_NAME, LAST_NAME FROM CUSTOMERS WHERE ID=?";
+ try (var connection = dataSource.getConnection();
+ var preparedStatement = connection.prepareStatement(sql)) {
+ preparedStatement.setInt(1, id);
+ try (ResultSet resultSet = preparedStatement.executeQuery()) {
+ if (resultSet.next()) {
+ return Optional.of(mapCustomer(resultSet));
+ }
+ return Optional.empty();
+ }
+ }
+ }
+
+ /**
+ * Returns all customer rows ordered by id.
+ *
+ * @return all customers in the table
+ * @throws SQLException if the database operation fails
+ */
+ public List findAll() throws SQLException {
+ var customers = new ArrayList();
+ var sql = "SELECT ID, FIRST_NAME, LAST_NAME FROM CUSTOMERS ORDER BY ID";
+ try (var connection = dataSource.getConnection();
+ var statement = connection.createStatement();
+ var resultSet = statement.executeQuery(sql)) {
+ while (resultSet.next()) {
+ customers.add(mapCustomer(resultSet));
+ }
+ }
+ return customers;
+ }
+
+ /**
+ * Updates a customer row.
+ *
+ * @param customer customer data with updated values
+ * @return number of rows updated, or zero if the row does not exist
+ * @throws SQLException if the database operation fails
+ */
+ public int update(final Customer customer) throws SQLException {
+ Objects.requireNonNull(customer);
+ var sql = "UPDATE CUSTOMERS SET FIRST_NAME=?, LAST_NAME=? WHERE ID=?";
+ try (var connection = dataSource.getConnection();
+ var preparedStatement = connection.prepareStatement(sql)) {
+ preparedStatement.setString(1, customer.firstName());
+ preparedStatement.setString(2, customer.lastName());
+ preparedStatement.setInt(3, customer.id());
+ var updated = preparedStatement.executeUpdate();
+ LOGGER.info("Updated customer with id {}, affected rows: {}", customer.id(), updated);
+ return updated;
+ }
+ }
+
+ /**
+ * Deletes a customer row.
+ *
+ * @param id customer identifier
+ * @return number of rows deleted, or zero if the row does not exist
+ * @throws SQLException if the database operation fails
+ */
+ public int delete(final int id) throws SQLException {
+ var sql = "DELETE FROM CUSTOMERS WHERE ID=?";
+ try (var connection = dataSource.getConnection();
+ var preparedStatement = connection.prepareStatement(sql)) {
+ preparedStatement.setInt(1, id);
+ var deleted = preparedStatement.executeUpdate();
+ LOGGER.info("Deleted customer with id {}, affected rows: {}", id, deleted);
+ return deleted;
+ }
+ }
+
+ private static Customer mapCustomer(final ResultSet resultSet) throws SQLException {
+ return new Customer(
+ resultSet.getInt("ID"),
+ resultSet.getString("FIRST_NAME"),
+ resultSet.getString("LAST_NAME"));
+ }
+}
diff --git a/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/AppTest.java b/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/AppTest.java
new file mode 100644
index 000000000000..617fe456c98b
--- /dev/null
+++ b/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/AppTest.java
@@ -0,0 +1,42 @@
+/*
+ * This project is licensed under the MIT license. Module table-data-gateway uses H2 database licensed under EPL (see epl-1.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.tabledatagateway;
+
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
+
+import org.junit.jupiter.api.Test;
+
+class AppTest {
+
+ @Test
+ void applicationShouldBeConstructible() {
+ assertDoesNotThrow(App::new);
+ }
+
+ @Test
+ void mainShouldRunSuccessfully() {
+ assertDoesNotThrow(() -> App.main(new String[0]));
+ }
+}
diff --git a/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/CustomerTableGatewayTest.java b/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/CustomerTableGatewayTest.java
new file mode 100644
index 000000000000..ee7d8f0c3251
--- /dev/null
+++ b/table-data-gateway/src/test/java/com/iluwatar/tabledatagateway/CustomerTableGatewayTest.java
@@ -0,0 +1,117 @@
+/*
+ * This project is licensed under the MIT license. Module table-data-gateway uses H2 database licensed under EPL (see epl-1.0.txt).
+ *
+ * The MIT License
+ * Copyright © 2014-2022 Ilkka Seppälä
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package com.iluwatar.tabledatagateway;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.sql.DriverManager;
+import java.sql.SQLException;
+import java.util.List;
+import javax.sql.DataSource;
+import org.h2.jdbcx.JdbcDataSource;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class CustomerTableGatewayTest {
+
+ private static final String DB_URL = "jdbc:h2:mem:tabledatagatewaytest;DB_CLOSE_DELAY=-1";
+
+ private DataSource dataSource;
+ private CustomerTableGateway gateway;
+
+ @BeforeEach
+ void setUp() throws SQLException {
+ dataSource = createDataSource();
+ execute(CustomerTableGateway.DELETE_SCHEMA_SQL);
+ execute(CustomerTableGateway.CREATE_SCHEMA_SQL);
+ gateway = new CustomerTableGateway(dataSource);
+ }
+
+ @AfterEach
+ void tearDown() throws SQLException {
+ execute(CustomerTableGateway.DELETE_SCHEMA_SQL);
+ }
+
+ private static DataSource createDataSource() {
+ var source = new JdbcDataSource();
+ source.setURL(DB_URL);
+ return source;
+ }
+
+ private static void execute(final String sql) throws SQLException {
+ try (var connection = DriverManager.getConnection(DB_URL);
+ var statement = connection.createStatement()) {
+ statement.execute(sql);
+ }
+ }
+
+ @Test
+ void insertAndFindByIdShouldReturnPersistedRow() throws SQLException {
+ var customer = new Customer(1, "Alice", "Smith");
+
+ assertEquals(1, gateway.insert(customer));
+ assertEquals(customer, gateway.findById(1).orElseThrow());
+ }
+
+ @Test
+ void findByIdShouldReturnEmptyWhenRowDoesNotExist() throws SQLException {
+ assertTrue(gateway.findById(99).isEmpty());
+ }
+
+ @Test
+ void findAllShouldReturnRowsInIdOrder() throws SQLException {
+ gateway.insert(new Customer(2, "Bob", "Jones"));
+ gateway.insert(new Customer(1, "Alice", "Smith"));
+
+ assertEquals(
+ List.of(new Customer(1, "Alice", "Smith"), new Customer(2, "Bob", "Jones")),
+ gateway.findAll());
+ }
+
+ @Test
+ void findAllShouldReturnEmptyWhenTableHasNoRows() throws SQLException {
+ assertTrue(gateway.findAll().isEmpty());
+ }
+
+ @Test
+ void updateShouldPersistNewValuesAndReportMissingRows() throws SQLException {
+ gateway.insert(new Customer(1, "Alice", "Smith"));
+
+ assertEquals(1, gateway.update(new Customer(1, "Alice", "Jones")));
+ assertEquals("Jones", gateway.findById(1).orElseThrow().lastName());
+ assertEquals(0, gateway.update(new Customer(99, "No", "Row")));
+ }
+
+ @Test
+ void deleteShouldRemoveRowAndReportMissingRows() throws SQLException {
+ gateway.insert(new Customer(1, "Alice", "Smith"));
+
+ assertEquals(1, gateway.delete(1));
+ assertEquals(0, gateway.delete(1));
+ assertTrue(gateway.findById(1).isEmpty());
+ }
+}