备忘录模式

src/main/java/top/fjy8018/designpattern/pattern/behavior/memento/Article.java

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+package top.fjy8018.designpattern.pattern.behavior.memento;
+
+import lombok.AllArgsConstructor;
+import lombok.Data;
+
+/**
+ * 文章，字段不宜过多，否则导致过大内存占用
+ *
+ * @author F嘉阳
+ * @date 2020/3/6 17:00
+ */
+@Data
+@AllArgsConstructor
+public class Article {
+
+    private String title;
+
+    private String content;
+
+    private String imgs;
+
+    /**
+     * 保存
+     *
+     * @return
+     */
+    public ArticleMemento saveToMemento() {
+        ArticleMemento articleMemento = new ArticleMemento(this.title, this.content, this.imgs);
+        return articleMemento;
+    }
+
+    /**
+     * 撤销
+     *
+     * @param articleMemento
+     */
+    public void undoFromMemento(ArticleMemento articleMemento) {
+        this.title = articleMemento.getTitle();
+        this.content = articleMemento.getContent();
+        this.imgs = articleMemento.getImgs();
+    }
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/memento/ArticleMemento.java

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+package top.fjy8018.designpattern.pattern.behavior.memento;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.ToString;
+import org.springframework.binding.message.StateManageableMessageContext;
+
+/**
+ * 文章备忘录（快照）
+ * 快照不需要set方法，只能通过构造器注入
+ * <p>
+ * Spring工作流中源码 {@link StateManageableMessageContext#createMessagesMemento()}
+ *
+ * @author F嘉阳
+ * @date 2020/3/6 17:03
+ */
+@Getter
+@ToString
+@AllArgsConstructor
+public class ArticleMemento {
+
+    private String title;
+
+    private String content;
+
+    private String imgs;
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/memento/ArticleMementoManager.java

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+package top.fjy8018.designpattern.pattern.behavior.memento;
+
+import java.util.Stack;
+
+/**
+ * 保存一个对象的某个状态，以便在适当的时候恢复对象
+ *
+ * @author F嘉阳
+ * @date 2020/3/6 17:04
+ */
+public class ArticleMementoManager {
+
+    /**
+     * 使用栈特性实现动作撤销
+     */
+    private final Stack<ArticleMemento> ARTICLE_MEMENTO_STACK = new Stack<ArticleMemento>();
+
+    public ArticleMemento getMemento() {
+        ArticleMemento articleMemento = ARTICLE_MEMENTO_STACK.pop();
+        return articleMemento;
+    }
+
+    public void addMemento(ArticleMemento articleMemento) {
+        ARTICLE_MEMENTO_STACK.push(articleMemento);
+    }
+
+}