這是 Cd Chen 在 2012/09 於 KSDG 的技術分享之投影片。

1. 實作資料存取
的抽象化
Cd Chen
http://www.niceStudio.com.tw/

2. 陳永昇 (Cd Chen)
經歷：
• 乃師實業技術總監
• 恆逸資訊講師
• 聯成電腦講師
• 碩誠資訊研發部經理
專長：
• Unix / Linux 系統管理與開發
• Java / Python / Perl / Objective-C /
C / C++ / PHP / Ruby
• Security / Agile / OOAD

3. • 全部都是 Java
• 完全不遵守 JSR
• 包含可能影響身
心健康的內容

4. 世間永遠不會改變的是...
不斷改變的
需求

5. 給我寫⼀一隻
“指令模式”
統計訂單金額的程式

6. public static void main(String[] args){
System.out.println(“開始統計”);
List<Order> orders = // ...;
double sum = 0.0;
for (Order order : orders) {
sum += order.getPrice();
}
System.out.println(
“總金額是: ” + sum
);
}

7. 給我寫⼀一隻
“指令模式”
“視窗介面”
統計訂單金額的程式

8. http://i.mtime.com/3176183/blog/5709802/

9. 內聚 & 耦合

10. Controller
View Model

11. Presentation
Business Logic
Data Access

12. 單⼀一責任原則

13. ConsoleUI
Presentation
OrderService
Business Logic
OrderRepository
Data Access

14. 給我寫⼀一隻
“指令模式”
“網頁介面”
統計訂單金額的程式

15. ConsoleUI
HtmlUI
Presentation
OrderService
Business Logic
OrderRepository
Data Access

16. 針對介面
而非實作

17. <<use>>
Main
Presentation
UserInterface
+showHint()
+showPrice(price: double)
<<class>>
ConsoleUserInterface
+showHint()
+showPrice(price: double)

18. public interface UserInterface {
void showHint();
void showPrice(double price);
}
public class ConsoleUI
ConsoleUI implements UserInterface {
public void showHint() {
Presentation System.out.println(" ");
}
public void showPrice(double price) {
Service System.out.println(" " + price);
}
Business Logic }
public static void main(String[] args) {
Repository UserInterface ui = ConsoleUI();
ui.showHint();
Data Access List<Order> orders = //
double price = 0.0;
...
for (Order order : orders)
price += order.getPrice();
ui.showPrice(price);
}

19. Data Access Layer??

20. 關聯式資料庫 NoSQL 其他
•Native Driver •MongoDB •File
•JDBC •CouchDB •Web Service
•Hibernate •Redis •...
•JPA •HBase
•... •...

21. 資料儲存在
“檔案資料庫”
“關聯式資料庫”
“NoSQL 資料庫”
...

22. <<use>>
Main
Data Access
OrderRepository
+findAll(): List<Order>
<<class>>
OrderRepositoryJpaImpl
+findAll(): List<Order>

23. public interface OrderRepository {
List<Order> findAll();
}
public class OrderRepositoryJpaImpl
implements OrderRepository {
ConsoleUI
public List<Order> findAll() {
Presentation // JPA …
}
}
Service
public static void main(String[] args) {
Business Logic UserInterface ui = ConsoleUI();
ui.showHint();
OrderRepository repo =
Repository new OrderRepositoryJpaImpl();
List<Order> orders = repo.findAll();
Data Access double price = 0.0;
for (Order order : orders)
price += order.getPrice();
ui.showPrice(price);
}

25. Spring Data

26. Spring Data
降低 DAL 耦合
•減少 DAL 開發
•簡化 DAL 實作
•支援 QueryDSL

28. IoC & AOP

29. // OrderRepository
public interface OrderRepository {
List<Order> findAll();
}
注入實作細節，
// Main Class 定義於外部的設定中，降
@Autowired
OrderRepository repo;
低元件間的耦合，進而提
高維護的彈性
@Autowired
UserInterface ui;
public static void main(String[] args) {
ui.showHint();
List<Order> orders = repo.findAll();
double price = 0.0;
for (Order order : orders)
price += order.getPrice();
ui.showPrice(price);
}

30. Base Commons
關聯式資料庫 JDBC / JPA
Big Data Apache Hadoop
Data-Grid GemFire
HTTP REST
Document MongoDB
Graph Neo4j
Column Stores HBase
Key-Value Redis

31. Repository
+save(entity: T): T
+findOne(id: ID): T
+findAll(): Iterator<T>
+count(): Long
+delete(entity: T)
CrudRepository
+exists(id: ID): boolean
...
+findAll(sort: Sort): Iterator<T>
+findAll(pageable: Pageable): Page<T>
PagingAndSortingRepository

32. Example:
Spring Data JPA

33. 減少 DAL 的開發

34. public class OrderRepositoryJpaImpl
implements OrderRepository {
List<Order> findAll() {
EntityManager em =
Query q = em.createQuery(“SELECT o FROM Order o”);
List<Order> results = new ArrayList<Order>();
for(Order order : q.getResultList()) {
results.add(order);
}
return results;
}
} No Spring-Data
public interface OrderJpaRepository
extends JpaRepository<Order, Long>, OrderRepository {
}
Yes, Spring-Data!!

35. 簡化 DAL 的實作

36. Method Name
Keywords

37. Keyword
findByFFFKKK
欄位名稱

38. public interface OrderJpaRepository
extends JpaRepository<Order, Long>, OrderRepository {
List<Order> findByDate(Date date);
List<Order> findByCustomer(Customer customer);
List<Order> findByCustomerAndDate(Customer c, Date d);
List<Order> findByCustomer_NameLike(String name);
List<Order> findByDateBefore(Date theDate);
List<Order> findByPriceLessThan(double price);
// ...
}
Method Name Keywords

39. Logic Keyword
AFTER After / IsAfter
BEFORE Before / IsBefore
CONTAINING Containing / IsContaining / Contains
BETWEEN Between / IsBetween
ENDING WITH EndingWith / IsEndingWith / EndsWith
EXISTS Exists
FALSE False / IsFalse
GREATER THAN GreaterThan / IsGreaterThan
GREATER THAN
GreaterThanEqual / IsGreaterThanEqual
EQUALS
IN In / IsIn
IS Is / Equals
IS NOT NULL NotNull / IsNotNull

40. Logic Keyword
IS NULL Null / IsNull
LESS THAN LessThan / IsLessThan
LESS THAN EQUALS LessThanEqual / IsLessThanEqual
LIKE Like / IsLike
NEAR Near / IsNear
NOT Not / IsNot
NOT LIKE NotLike / IsNotLike
REGEX Regex / MatchesRegex / Maches
STARTING WITH StartingWith / IsStartingWith / StartsWith
TRUE True / IsTrue
WITHIN Within / IsWithin

41. @Query Annotation

42. // Order
@Entity
@NamedQuery(
name=”Order.findByProfitThan100”,
query=”select o from Order o where price - cost > 100”)
class Order {
// ...
}
// OrderJpaRepository
public interface OrderJpaRepository
extends JpaRepository<Order, Long>, OrderRepository {
List<Order> findByProfitThan100();
@Query(“select o from Order o where price - cost > 0”)
List<Order> findByPositiveProfit();
@Query(“select o from Order o where price > ?1”)
List<Order> findByPriceGreaterThanArg(double price);
// ....
}
@Query Annotation

43. Thank you.
http://slidesha.re/Oa2LYT