feat: 4단계 - Simple Entity Object

src/main/java/jdbc/RowMapper.java

@@ -5,5 +5,6 @@
 
 @FunctionalInterface
 public interface RowMapper<T> {
-    T mapRow(final ResultSet resultSet) throws SQLException;
+    T mapRow(final ResultSet resultSet)
+        throws SQLException, InstantiationException, IllegalAccessException;
 }

src/main/java/persistence/Application.java

@@ -7,7 +7,7 @@
 import jdbc.RowMapper;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import persistence.sql.QueryTranslator;
+import persistence.sql.QueryBuilder;
 import persistence.sql.ddl.entity.Person;
 
 public class Application {
@@ -28,19 +28,19 @@ public static void main(String[] args) {
 
             final JdbcTemplate jdbcTemplate = new JdbcTemplate(server.getConnection());
 
-            QueryTranslator queryTranslator = new QueryTranslator();
+            QueryBuilder queryBuilder = new QueryBuilder();
 
-            jdbcTemplate.execute(queryTranslator.getCreateTableQuery(Person.class));
+            jdbcTemplate.execute(queryBuilder.getCreateTableQuery(Person.class));
 
-            executeInitializedQuery(jdbcTemplate, queryTranslator);
+            executeInitializedQuery(jdbcTemplate, queryBuilder);
 
-            querySelectAll(jdbcTemplate, queryTranslator);
+            querySelectAll(jdbcTemplate, queryBuilder);
 
-            querySelectById(jdbcTemplate, queryTranslator);
+            querySelectById(jdbcTemplate, queryBuilder);
 
-            jdbcTemplate.execute(queryTranslator.getDeleteByIdQuery(Person.class, 2L));
+            jdbcTemplate.execute(queryBuilder.getDeleteByIdQuery(Person.class, 2L));
 
-            querySelectAll(jdbcTemplate, queryTranslator);
+            querySelectAll(jdbcTemplate, queryBuilder);
 
             server.stop();
         } catch (Exception e) {
@@ -50,33 +50,33 @@ public static void main(String[] args) {
         }
     }
 
-    private static void querySelectById(JdbcTemplate jdbcTemplate, QueryTranslator queryTranslator) {
+    private static void querySelectById(JdbcTemplate jdbcTemplate, QueryBuilder queryBuilder) {
         Person person = jdbcTemplate.queryForObject(
-            queryTranslator.getSelectByIdQuery(Person.class, 2L),
+            queryBuilder.getSelectByIdQuery(Person.class, 2L),
             rowMapper
         );
 
         logger.info("Person: {}", person);
     }
 
-    private static void querySelectAll(JdbcTemplate jdbcTemplate, QueryTranslator queryTranslator) {
+    private static void querySelectAll(JdbcTemplate jdbcTemplate, QueryBuilder queryBuilder) {
         List<Person> persons = jdbcTemplate.query(
-            queryTranslator.getSelectAllQuery(Person.class),
+            queryBuilder.getSelectAllQuery(Person.class),
             rowMapper
         );
 
         persons.forEach(person -> logger.info("Person: {}", person));
     }
 
-    private static void executeInitializedQuery(JdbcTemplate jdbcTemplate, QueryTranslator queryTranslator) {
+    private static void executeInitializedQuery(JdbcTemplate jdbcTemplate, QueryBuilder queryBuilder) {
         List<Person> persons = List.of(
             new Person("John", 23, "john@gmail.com"),
             new Person("Smith", 33, "smith@gmail.com"),
             new Person("rolroralra", 37, "rolroralra@gmail.com")
         );
 
         persons.stream()
-            .map(queryTranslator::getInsertQuery)
+            .map(queryBuilder::getInsertQuery)
             .forEach(jdbcTemplate::execute);
     }
 

src/main/java/persistence/entity/EntityManager.java

@@ -0,0 +1,29 @@
+package persistence.entity;
+
+public interface EntityManager {
+    /**
+     * Finds an entity by its id
+     *
+     * @param entityClass the entity class
+     * @param id the id of the entity
+     * @return the entity
+     *
+     * @param <T> the entity type
+     */
+    <T> T find(Class<T> entityClass, Long id);
+
+    /**
+     * Persists the entity object
+     *
+     * @param entity entity object to persist
+     * @return the persisted entity object
+     */
+    Object persist(Object entity);
+
+    /**
+     * Removes the entity object
+     *
+     * @param entity entity object to remove
+     */
+    void remove(Object entity);
+}

src/main/java/persistence/entity/EntityRowMapperFactory.java

@@ -0,0 +1,54 @@
+package persistence.entity;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.util.List;
+import java.util.stream.Collectors;
+import jdbc.RowMapper;
+import persistence.exception.ReflectionRuntimeException;
+import persistence.sql.ddl.ColumnQueryBuilder;
+
+public class EntityRowMapperFactory {
+
+    private EntityRowMapperFactory() {
+        // Do nothing
+    }
+
+    public static class CacheEntityRowMapperFactory {
+        private CacheEntityRowMapperFactory() {
+            // Do nothing
+        }
+
+        private static final EntityRowMapperFactory INSTANCE = new EntityRowMapperFactory();
+    }
+
+    public static EntityRowMapperFactory getInstance() {
+        return CacheEntityRowMapperFactory.INSTANCE;
+    }
+
+    public <T> RowMapper<T> getRowMapper(Class<T> entityClass) {
+        return resultSet -> {
+            try {
+                ColumnQueryBuilder columnQueryBuilder = new ColumnQueryBuilder();
+                Constructor<T> declaredConstructor = entityClass.getDeclaredConstructor();
+                declaredConstructor.setAccessible(true);
+                T entity = entityClass.getDeclaredConstructor().newInstance();
+
+                List<Field> columnFieldList = columnQueryBuilder.getColumnFieldStream(entityClass)
+                    .collect(Collectors.toList());
+
+                for (Field field : columnFieldList) {
+                    field.setAccessible(true);
+                    String columnName = columnQueryBuilder.getColumnNameFrom(field);
+                    field.set(entity, resultSet.getObject(columnName));
+                }
+
+                return entity;
+            } catch (InstantiationException | IllegalAccessException | NoSuchMethodException |
+                     InvocationTargetException e) {
+                throw new ReflectionRuntimeException(entityClass, e);
+            }
+        };
+    }
+}

src/main/java/persistence/entity/impl/EntityManagerImpl.java

@@ -0,0 +1,48 @@
+package persistence.entity.impl;
+
+import jdbc.JdbcTemplate;
+import persistence.entity.EntityManager;
+import persistence.entity.EntityRowMapperFactory;
+import persistence.sql.QueryBuilder;
+
+public class EntityManagerImpl implements EntityManager {
+    private final JdbcTemplate jdbcTemplate;
+
+    private final QueryBuilder queryBuilder;
+
+    public EntityManagerImpl(JdbcTemplate jdbcTemplate) {
+        this(jdbcTemplate, new QueryBuilder());
+    }
+
+    public EntityManagerImpl(JdbcTemplate jdbcTemplate, QueryBuilder queryBuilder) {
+        this.jdbcTemplate = jdbcTemplate;
+        this.queryBuilder = queryBuilder;
+    }
+
+
+    @Override
+    public <T> T find(Class<T> entityClass, Long id) {
+        String selectByIdQuery = queryBuilder.getSelectByIdQuery(entityClass, id);
+
+        return jdbcTemplate.queryForObject(
+            selectByIdQuery,
+            EntityRowMapperFactory.getInstance().getRowMapper(entityClass)
+        );
+    }
+
+    @Override
+    public Object persist(Object entity) {
+        String insertQuery = queryBuilder.getInsertQuery(entity);
+
+        jdbcTemplate.execute(insertQuery);
+
+        return entity;
+    }
+
+    @Override
+    public void remove(Object entity) {
+        String deleteQueryFromEntity = queryBuilder.getDeleteQueryFromEntity(entity);
+
+        jdbcTemplate.execute(deleteQueryFromEntity);
+    }
+}

src/main/java/persistence/exception/ReflectionRuntimeException.java

@@ -0,0 +1,7 @@
+package persistence.exception;
+
+public class ReflectionRuntimeException extends RuntimeException {
+    public ReflectionRuntimeException(Class<?> clazz, Exception e) {
+        super("Reflection error on class: " + clazz.getName(), e);
+    }
+}

src/main/java/persistence/sql/exception/UnsupportedClassException.java → src/main/java/persistence/exception/UnsupportedClassException.java

@@ -1,4 +1,4 @@
-package persistence.sql.exception;
+package persistence.exception;
 
 public class UnsupportedClassException extends RuntimeException {
 

src/main/java/persistence/sql/exception/constraints/UnsupportedFieldException.java → src/main/java/persistence/exception/UnsupportedFieldException.java

@@ -1,4 +1,4 @@
-package persistence.sql.exception.constraints;
+package persistence.exception;
 
 import java.lang.reflect.Field;
 

src/main/java/persistence/sql/AbstractQueryBuilder.java

@@ -0,0 +1,70 @@
+package persistence.sql;
+
+import jakarta.persistence.Column;
+import jakarta.persistence.Id;
+import jakarta.persistence.Transient;
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.stream.Stream;
+import persistence.exception.UnsupportedClassException;
+
+public abstract class AbstractQueryBuilder {
+
+    protected AbstractQueryBuilder() {
+
+    }
+
+    /**
+     * Get the stream of fields that are not annotated with <code>@Transient</code> from the entity class
+     * @param entityClass Entity class
+     * @return Stream of fields that are annotated with <code>@Column</code> or <code>@Id</code>
+     * @see Column
+     * @see Id
+     * @see Transient
+     */
+    protected Stream<Field> getColumnFieldStream(Class<?> entityClass) {
+        return Arrays.stream(entityClass.getDeclaredFields())
+            .filter(field -> !field.isAnnotationPresent(Transient.class))
+            .sorted(Comparator.comparing(field -> field.isAnnotationPresent(Id.class) ? 0 : 1));
+    }
+
+    /**
+     * Get the column name from the field
+     * @param field Field
+     * @return Column name from the field
+     */
+    protected String getColumnNameFrom(Field field) {
+        if (!field.isAnnotationPresent(Column.class)) {
+            return field.getName();
+        }
+
+        Column column = field.getAnnotation(Column.class);
+
+        if (column.name().isEmpty()) {
+            return field.getName();
+        }
+
+        return column.name();
+    }
+
+    /**
+     * Get the column value from the object
+     * @param columnValue Column value object
+     * @return Column value from the object
+     */
+    protected String getColumnValueFromObject(Object columnValue) {
+        // TODO: remove this else-if statement
+        if (columnValue.getClass().equals(Boolean.class)) {
+            return columnValue == Boolean.TRUE ? "1" : "0";
+        } else if (columnValue.getClass().equals(String.class)) {
+            return String.format("'%s'", columnValue);
+        } else if (columnValue.getClass().equals(Integer.class)) {
+            return columnValue.toString();
+        } else if (columnValue.getClass().equals(Long.class)) {
+            return columnValue.toString();
+        }
+
+        throw new UnsupportedClassException(columnValue.getClass());
+    }
+}

src/main/java/persistence/sql/QueryBuilder.java

@@ -0,0 +1,86 @@
+package persistence.sql;
+
+
+import java.lang.reflect.Field;
+import persistence.sql.ddl.CreateQueryBuilder;
+import persistence.sql.ddl.DropQueryBuilder;
+import persistence.sql.ddl.TableQueryBuilder;
+import persistence.sql.dml.DeleteQueryBuilder;
+import persistence.sql.dml.InsertQueryBuilder;
+import persistence.sql.dml.SelectQueryBuilder;
+
+public class QueryBuilder extends AbstractQueryBuilder {
+
+    private final TableQueryBuilder tableQueryBuilder;
+
+    private final SelectQueryBuilder selectQueryBuilder;
+
+    private final DeleteQueryBuilder deleteQueryBuilder;
+
+    private final InsertQueryBuilder insertQueryTranslator;
+
+    private final DropQueryBuilder dropQueryBuilder;
+
+    private final CreateQueryBuilder createQueryBuilder;
+
+    public QueryBuilder() {
+        this(new TableQueryBuilder());
+    }
+
+    public QueryBuilder(TableQueryBuilder tableQueryBuilder) {
+        this.tableQueryBuilder = tableQueryBuilder;
+        this.selectQueryBuilder = new SelectQueryBuilder(tableQueryBuilder);
+        this.deleteQueryBuilder = new DeleteQueryBuilder(tableQueryBuilder);
+        this.insertQueryTranslator = new InsertQueryBuilder(tableQueryBuilder);
+        this.dropQueryBuilder = new DropQueryBuilder(tableQueryBuilder);
+        this.createQueryBuilder = new CreateQueryBuilder(tableQueryBuilder);
+    }
+
+    public String getCreateTableQuery(final Class<?> entityClass) {
+        return createQueryBuilder.getCreateTableQuery(entityClass);
+    }
+
+    public String getDropTableQuery(Class<?> entityClass) {
+        return dropQueryBuilder.getDropTableQuery(entityClass);
+    }
+
+    public String getInsertQuery(Object entity) {
+        return insertQueryTranslator.getInsertQuery(entity);
+    }
+
+    public String getSelectAllQuery(Class<?> entityClass) {
+        return selectQueryBuilder.getSelectAllQuery(entityClass);
+    }
+
+    public String getSelectByIdQuery(Class<?> entityClass, Object id) {
+        return selectQueryBuilder.getSelectByIdQuery(entityClass, id);
+    }
+
+    public String getSelectCountQuery(Class<?> entityClass) {
+        return selectQueryBuilder.getSelectCountQuery(entityClass);
+    }
+
+    public String getDeleteAllQuery(Class<?> entityClass) {
+        return deleteQueryBuilder.getDeleteAllQuery(entityClass);
+    }
+
+    public String getDeleteByIdQuery(Class<?> entityClass, Object id) {
+        return deleteQueryBuilder.getDeleteByIdQuery(entityClass, id);
+    }
+
+    public String getDeleteQueryFromEntity(Object entity) {
+        return deleteQueryBuilder.getDeleteQueryFromEntity(entity);
+    }
+
+    public String getTableNameFrom(Class<?> entityClass) {
+        return tableQueryBuilder.getTableNameFrom(entityClass);
+    }
+
+    public String getColumnDefinitionFrom(Field field) {
+        return createQueryBuilder.getColumnDefinitionFrom(field);
+    }
+
+    public String getColumnDefinitionsFrom(Class<?> entityClass) {
+        return createQueryBuilder.getColumnDefinitionsFrom(entityClass);
+    }
+}