docs: Chinese translations updates (#1706)

* add state and callback pattern * add command and template-method pattern * add iterator pattern * add bridege and DI pattern * fix issue #1600 * add converter,proxy,visitor pattern * add caching,composite,delegation,dirty-flag,interpreter patterns * add dao and producer-consumer * add dto and provate class data pattern * fix #1646 png path problems * fix #1646 composite png path case problem * add abstract document pattern and version-number pattern * add ambassador pattern * add acyclic-visitor and api-gateway pattern * add abstract-factory pattern * add active-object pattern * add aggregator-microservices and arrange-act-assert pattern Co-authored-by: Mike <admin@xiaod.info> Co-authored-by: Subhrodip Mohanta <hello@subho.xyz> Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>
2021-04-26 15:58:01 +08:00
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+---
+layout: pattern
+title: Version Number
+folder: versionnumber
+permalink: /patterns/versionnumber/
+description: Entity versioning with version number
+
+categories:
+ - Concurrency
+
+tags:
+ - Data access
+ - Microservices
+---
+
+## 名字 / 分类
+
+版本号
+
+## 或称
+
+实体版本控制，乐观锁。
+
+## 目的
+
+解决多个客户端尝试同时更新同一实体时的并发冲突。
+
+## 解释
+
+现实世界的例子
+
+> 爱丽丝（Alice）和鲍勃（Bob）正在管理书，该书存储在数据库中。 我们的英雄们正在同时进行更改，我们需要某种机制来防止他们相互覆盖。
+
+通俗地说
+
+> 版本号模式可防止对同一实体进行并发更新。
+
+维基百科说
+
+> 乐观并发控制假设多个事务可以频繁完成而不会互相干扰。 在运行时，事务使用数据资源而不获取这些资源的锁。 在提交之前，每个事务都将验证没有其他事务修改了已读取的数据。如果检查发现有冲突的修改，则提交的事务将回滚并可以重新启动。
+
+**程序示例**
+
+我们有`Book` 已版本化的实体，它有一个复制构造函数。
+
+```java
+public class Book {
+  private long id;
+  private String title = "";
+  private String author = "";
+
+  private long version = 0; // version number
+
+  public Book(Book book) {
+    this.id = book.id;
+    this.title = book.title;
+    this.author = book.author;
+    this.version = book.version;
+  }
+
+  // getters and setters are omitted here
+}
+```
+
+我们还有一个 `BookRepository`, 它实现了并发控制。
+
+```java
+public class BookRepository {
+  private final Map<Long, Book> collection = new HashMap<>();
+
+  public void update(Book book) throws BookNotFoundException, VersionMismatchException {
+    if (!collection.containsKey(book.getId())) {
+      throw new BookNotFoundException("Not found book with id: " + book.getId());
+    }
+
+    var latestBook = collection.get(book.getId());
+    if (book.getVersion() != latestBook.getVersion()) {
+      throw new VersionMismatchException(
+        "Tried to update stale version " + book.getVersion()
+          + " while actual version is " + latestBook.getVersion()
+      );
+    }
+
+    // update version, including client representation - modify by reference here
+    book.setVersion(book.getVersion() + 1);
+
+    // save book copy to repository
+    collection.put(book.getId(), new Book(book));
+  }
+
+  public Book get(long bookId) throws BookNotFoundException {
+    if (!collection.containsKey(bookId)) {
+      throw new BookNotFoundException("Not found book with id: " + bookId);
+    }
+
+    // return copy of the book
+    return new Book(collection.get(bookId));
+  }
+}
+```
+
+这是实践中的并发控制：
+
+```java
+var bookId = 1;
+// Alice and Bob took the book concurrently
+final var aliceBook = bookRepository.get(bookId);
+final var bobBook = bookRepository.get(bookId);
+
+aliceBook.setTitle("Kama Sutra"); // Alice has updated book title
+bookRepository.update(aliceBook); // and successfully saved book in database
+LOGGER.info("Alice updates the book with new version {}", aliceBook.getVersion());
+
+// now Bob has the stale version of the book with empty title and version = 0
+// while actual book in database has filled title and version = 1
+bobBook.setAuthor("Vatsyayana Mallanaga"); // Bob updates the author
+try {
+  LOGGER.info("Bob tries to update the book with his version {}", bobBook.getVersion());
+  bookRepository.update(bobBook); // Bob tries to save his book to database
+} catch (VersionMismatchException e) {
+  // Bob update fails, and book in repository remained untouchable
+  LOGGER.info("Exception: {}", e.getMessage());
+  // Now Bob should reread actual book from repository, do his changes again and save again
+}
+```
+
+程序输出：
+
+```java
+Alice updates the book with new version 1
+Bob tries to update the book with his version 0
+Exception: Tried to update stale version 0 while actual version is 1
+```
+
+## 类图
+
+![alt text](../../version-number/etc/version-number.urm.png "Version Number pattern class diagram")
+
+## 适用性
+
+将版本号用于：
+
+* 解决对数据的并发写访问
+* 强的数据一致性
+
+## 教程
+* [Version Number Pattern Tutorial](http://www.java2s.com/Tutorial/Java/0355__JPA/VersioningEntity.htm)
+
+## 已知用途
+ * [Hibernate](https://vladmihalcea.com/jpa-entity-version-property-hibernate/)
+ * [Elasticsearch](https://www.elastic.co/guide/en/elasticsearch/reference/current/docs-index_.html#index-versioning)
+ * [Apache Solr](https://lucene.apache.org/solr/guide/6_6/updating-parts-of-documents.html)
+
+## 意义
+版本号模式允许实现并发控制，通常通过乐观离线锁模式来完成。
+
+## 相关模式
+* [Optimistic Offline Lock](https://martinfowler.com/eaaCatalog/optimisticOfflineLock.html)
+
+## 鸣谢
+* [Optimistic Locking in JPA](https://www.baeldung.com/jpa-optimistic-locking)
+* [JPA entity versioning](https://www.byteslounge.com/tutorials/jpa-entity-versioning-version-and-optimistic-locking)
+* [J2EE Design Patterns](http://ommolketab.ir/aaf-lib/axkwht7wxrhvgs2aqkxse8hihyu9zv.pdf)