Merge pull request #407 from iluwatar/refactor-dao

Solves #404 Refactor dao

dao/etc/dao.ucls

@@ -1,45 +1,71 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <class-diagram version="1.1.8" icons="true" always-add-relationships="false" generalizations="true" realizations="true" 
   associations="true" dependencies="false" nesting-relationships="true">  
-  <class id="1" language="java" name="com.iluwatar.Customer" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/Customer.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="176" y="337"/>    
+  <class id="1" language="java" name="com.iluwatar.dao.App" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/App.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="910" y="191"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
-      <attributes public="true" package="true" protected="true" private="true" static="true"/>      
-      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="false" static="true"/>    
     </display>  
   </class>  
-  <class id="2" language="java" name="com.iluwatar.CustomerDaoImpl" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/CustomerDaoImpl.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="540" y="334"/>    
+  <interface id="2" language="java" name="com.iluwatar.dao.CustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/CustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="536" y="187"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
+  </interface>  
+  <class id="3" language="java" name="com.iluwatar.dao.InMemoryCustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/InMemoryCustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="289" y="455"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="true" static="true"/>    
+    </display>  
   </class>  
-  <interface id="3" language="java" name="com.iluwatar.CustomerDao" project="dao" 
-    file="/dao/src/main/java/com/iluwatar/CustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
-    <position height="-1" width="-1" x="536" y="131"/>    
+  <class id="4" language="java" name="com.iluwatar.dao.DBCustomerDao" project="dao" 
+    file="/dao/src/main/java/com/iluwatar/dao/DBCustomerDao.java" binary="false" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="751" y="456"/>    
+    <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
+      sort-features="false" accessors="true" visibility="true">      
+      <attributes public="true" package="true" protected="true" private="false" static="true"/>      
+      <operations public="true" package="true" protected="true" private="false" static="true"/>    
+    </display>  
+  </class>  
+  <interface id="5" language="java" name="javax.sql.DataSource" project="dao" 
+    file="/opt/Softwares/Eclipses/MARS/eclipse/jre/lib/rt.jar" binary="true" corner="BOTTOM_RIGHT">    
+    <position height="-1" width="-1" x="1083" y="459"/>    
     <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
       sort-features="false" accessors="true" visibility="true">      
       <attributes public="true" package="true" protected="true" private="true" static="true"/>      
       <operations public="true" package="true" protected="true" private="true" static="true"/>    
     </display>  
   </interface>  
-  <realization id="4">    
-    <end type="SOURCE" refId="2"/>    
-    <end type="TARGET" refId="3"/>  
-  </realization>  
-  <association id="5">    
-    <end type="SOURCE" refId="2" navigable="false">      
-      <attribute id="6" name="customers"/>      
-      <multiplicity id="7" minimum="0" maximum="2147483647"/>    
+  <association id="6">    
+    <end type="SOURCE" refId="4" navigable="false">      
+      <attribute id="7" name="dataSource"/>      
+      <multiplicity id="8" minimum="0" maximum="1"/>    
     </end>    
-    <end type="TARGET" refId="1" navigable="true"/>    
+    <end type="TARGET" refId="5" navigable="true"/>    
     <display labels="true" multiplicity="true"/>  
   </association>  
+  <realization id="9">    
+    <end type="SOURCE" refId="3"/>    
+    <end type="TARGET" refId="2"/>  
+  </realization>  
+  <dependency id="10">    
+    <end type="SOURCE" refId="1"/>    
+    <end type="TARGET" refId="2"/>  
+  </dependency>  
+  <realization id="11">    
+    <end type="SOURCE" refId="4"/>    
+    <end type="TARGET" refId="2"/>  
+  </realization>  
   <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" 
     sort-features="false" accessors="true" visibility="true">    
     <attributes public="true" package="true" protected="true" private="true" static="true"/>    

dao/pom.xml

@@ -44,6 +44,18 @@
       <groupId>log4j</groupId>
       <artifactId>log4j</artifactId>
     </dependency>
+    <dependency>
+        <groupId>com.h2database</groupId>
+        <artifactId>h2</artifactId>
+      </dependency>
+    <dependency>
+      <groupId>de.bechte.junit</groupId>
+      <artifactId>junit-hierarchicalcontextrunner</artifactId>
+    </dependency>
+    <dependency>
+        <groupId>org.mockito</groupId>
+        <artifactId>mockito-core</artifactId>
+    </dependency>
   </dependencies>
 
   <build>

dao/src/main/java/com/iluwatar/dao/App.java

@@ -20,49 +20,101 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Stream;
+
+import javax.sql.DataSource;
 
 import org.apache.log4j.Logger;
+import org.h2.jdbcx.JdbcDataSource;
 
 /**
- * 
  * Data Access Object (DAO) is an object that provides an abstract interface to some type of
  * database or other persistence mechanism. By mapping application calls to the persistence layer,
  * DAO provide some specific data operations without exposing details of the database. This
  * isolation supports the Single responsibility principle. It separates what data accesses the
  * application needs, in terms of domain-specific objects and data types (the public interface of
  * the DAO), from how these needs can be satisfied with a specific DBMS.
- * <p>
- * With the DAO pattern, we can use various method calls to retrieve/add/delete/update data without
- * directly interacting with the data. The below example demonstrates basic CRUD operations: select,
- * add, update, and delete.
+ *
+ * <p>With the DAO pattern, we can use various method calls to retrieve/add/delete/update data 
+ * without directly interacting with the data source. The below example demonstrates basic CRUD 
+ * operations: select, add, update, and delete.
+ * 
  * 
  */
 public class App {
-
+  private static final String DB_URL = "jdbc:h2:~/dao:customerdb";
   private static Logger log = Logger.getLogger(App.class);
-
+  
   /**
    * Program entry point.
    * 
    * @param args command line args.
+   * @throws Exception if any error occurs. 
    */
-  public static void main(final String[] args) {
-    final CustomerDao customerDao = new CustomerDaoImpl(generateSampleCustomers());
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
-    log.info("customerDao.getCusterById(2): " + customerDao.getCustomerById(2));
+  public static void main(final String[] args) throws Exception {
+    final CustomerDao inMemoryDao = new InMemoryCustomerDao();
+    performOperationsUsing(inMemoryDao);
+
+    final DataSource dataSource = createDataSource();
+    createSchema(dataSource);
+    final CustomerDao dbDao = new DbCustomerDao(dataSource);
+    performOperationsUsing(dbDao);
+    deleteSchema(dataSource);
+  }
+
+  private static void deleteSchema(DataSource dataSource) throws SQLException {
+    try (Connection connection = dataSource.getConnection();
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.DELETE_SCHEMA_SQL);
+    }
+  }
+
+  private static void createSchema(DataSource dataSource) throws SQLException {
+    try (Connection connection = dataSource.getConnection();
+        Statement statement = connection.createStatement()) {
+      statement.execute(CustomerSchemaSql.CREATE_SCHEMA_SQL);
+    }
+  }
+
+  private static DataSource createDataSource() {
+    JdbcDataSource dataSource = new JdbcDataSource();
+    dataSource.setURL(DB_URL);
+    return dataSource;
+  }
+
+  private static void performOperationsUsing(final CustomerDao customerDao) throws Exception {
+    addCustomers(customerDao);
+    log.info("customerDao.getAllCustomers(): ");
+    try (Stream<Customer> customerStream = customerDao.getAll()) {
+      customerStream.forEach((customer) -> log.info(customer));
+    }
+    log.info("customerDao.getCustomerById(2): " + customerDao.getById(2));
     final Customer customer = new Customer(4, "Dan", "Danson");
-    customerDao.addCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
+    customerDao.add(customer);
+    log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
     customer.setFirstName("Daniel");
     customer.setLastName("Danielson");
-    customerDao.updateCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
-    customerDao.deleteCustomer(customer);
-    log.info("customerDao.getAllCustomers(): " + customerDao.getAllCustomers());
+    customerDao.update(customer);
+    log.info("customerDao.getAllCustomers(): ");
+    try (Stream<Customer> customerStream = customerDao.getAll()) {
+      customerStream.forEach((cust) -> log.info(cust));
+    }
+    customerDao.delete(customer);
+    log.info("customerDao.getAllCustomers(): " + customerDao.getAll());
+  }
+
+  private static void addCustomers(CustomerDao customerDao) throws Exception {
+    for (Customer customer : generateSampleCustomers()) {
+      customerDao.add(customer);
+    }
   }
 
   /**

dao/src/main/java/com/iluwatar/dao/Customer.java

@@ -20,11 +20,11 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
 /**
- * 
- * Customer
+ * A customer POJO that represents the data that will be read from the data source.
  *
  */
 public class Customer {
@@ -34,7 +34,7 @@ public class Customer {
   private String lastName;
 
   /**
-   * Constructor
+   * Creates an instance of customer.
    */
   public Customer(final int id, final String firstName, final String lastName) {
     this.id = id;
@@ -73,12 +73,12 @@ public String toString() {
   }
 
   @Override
-  public boolean equals(final Object o) {
+  public boolean equals(final Object that) {
     boolean isEqual = false;
-    if (this == o) {
+    if (this == that) {
       isEqual = true;
-    } else if (o != null && getClass() == o.getClass()) {
-      final Customer customer = (Customer) o;
+    } else if (that != null && getClass() == that.getClass()) {
+      final Customer customer = (Customer) that;
       if (getId() == customer.getId()) {
         isEqual = true;
       }

dao/src/main/java/com/iluwatar/dao/CustomerDao.java

@@ -20,24 +20,62 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+
 package com.iluwatar.dao;
 
-import java.util.List;
+import java.util.Optional;
+import java.util.stream.Stream;
 
 /**
+ * In an application the Data Access Object (DAO) is a part of Data access layer. It is an object
+ * that provides an interface to some type of persistence mechanism. By mapping application calls
+ * to the persistence layer, DAO provides some specific data operations without exposing details 
+ * of the database. This isolation supports the Single responsibility principle. It separates what
+ * data accesses the application needs, in terms of domain-specific objects and data types 
+ * (the public interface of the DAO), from how these needs can be satisfied with a specific DBMS,
+ * database schema, etc.
  * 
- * CustomerDao
- *
+ * <p>Any change in the way data is stored and retrieved will not change the client code as the 
+ * client will be using interface and need not worry about exact source.
+ * 
+ * @see InMemoryCustomerDao
+ * @see DbCustomerDao
  */
 public interface CustomerDao {
 
-  List<Customer> getAllCustomers();
-
-  Customer getCustomerById(int id);
+  /**
+   * @return all the customers as a stream. The stream may be lazily or eagerly evaluated based 
+   *     on the implementation. The stream must be closed after use.
+   * @throws Exception if any error occurs.
+   */
+  Stream<Customer> getAll() throws Exception;
+
+  /**
+   * @param id unique identifier of the customer.
+   * @return an optional with customer if a customer with unique identifier <code>id</code>
+   *     exists, empty optional otherwise.
+   * @throws Exception if any error occurs.
+   */
+  Optional<Customer> getById(int id) throws Exception;
 
-  void addCustomer(Customer customer);
+  /**
+   * @param customer the customer to be added.
+   * @return true if customer is successfully added, false if customer already exists.
+   * @throws Exception if any error occurs.
+   */
+  boolean add(Customer customer) throws Exception;
 
-  void updateCustomer(Customer customer);
+  /**
+   * @param customer the customer to be updated.
+   * @return true if customer exists and is successfully updated, false otherwise.
+   * @throws Exception if any error occurs.
+   */
+  boolean update(Customer customer) throws Exception;
 
-  void deleteCustomer(Customer customer);
+  /**
+   * @param customer the customer to be deleted.
+   * @return true if customer exists and is successfully deleted, false otherwise.
+   * @throws Exception if any error occurs.
+   */
+  boolean delete(Customer customer) throws Exception;
 }