设计模式-访问者模式

Author: dolyw

DesignPattern/src/main/java/com/design/visitor/BoardComputerNodeImpl.java

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+package com.design.visitor;
+
+/**
+ * 计算机主板具体节点
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class BoardComputerNodeImpl extends ComputerNode {
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+
+    @Override
+    public double getPrice() {
+        return 1000;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/ComputerNode.java

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+package com.design.visitor;
+
+/**
+ * 计算机抽象节点
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public abstract class ComputerNode {
+
+    public abstract void accept(Visitor visitor);
+
+    /**
+     * 原始价格
+     * @return
+     */
+    public double getPrice() {
+        return 0;
+    }
+
+}

DesignPattern/src/main/java/com/design/visitor/ComputerStructure.java

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+package com.design.visitor;
+
+/**
+ * 计算机结构对象，也可以同时充当具体节点的作用
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class ComputerStructure extends ComputerNode {
+
+    /*ComputerNode computerNode = new CpuComputerNodeImpl();
+    ComputerNode memoryComputerNode = new MemoryComputerNodeImpl();
+    ComputerNode boardComputerNode = new BoardComputerNodeImpl();*/
+
+    protected ComputerNode[] computerNodeArray;
+
+    public ComputerStructure() {
+        computerNodeArray = new ComputerNode[] {new CpuComputerNodeImpl(),
+                new MemoryComputerNodeImpl(), new BoardComputerNodeImpl()};
+    }
+
+    @Override
+    public void accept(Visitor visitor) {
+        /*this.computerNode.accept(visitor);
+        this.memoryComputerNode.accept(visitor);
+        this.boardComputerNode.accept(visitor);*/
+        for (ComputerNode computerNode : computerNodeArray) {
+            computerNode.accept(visitor);
+        }
+        // 整个结构对象，也同时充当节点的作用就需要调用
+        visitor.visit(this);
+    }
+
+    @Override
+    public double getPrice() {
+        // 计算机除去CPU内存主板后其他东西的总和
+        return 1000;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/CorpVisitorImpl.java

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+package com.design.visitor;
+
+/**
+ * 公司访问者，CPU 85折，内存7折，主板8折，其他6折
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class CorpVisitorImpl implements Visitor {
+
+    private double totalPrice = 0.0;
+
+    @Override
+    public void visit(CpuComputerNodeImpl cpuComputerNode) {
+        totalPrice = totalPrice + cpuComputerNode.getPrice() * 0.85;
+    }
+
+    @Override
+    public void visit(MemoryComputerNodeImpl memoryComputerNode) {
+        totalPrice = totalPrice + memoryComputerNode.getPrice() * 0.7;
+    }
+
+    @Override
+    public void visit(BoardComputerNodeImpl boardComputerNode) {
+        totalPrice = totalPrice + boardComputerNode.getPrice() * 0.8;
+    }
+
+    /**
+     * 总结点本身触发
+     *
+     * @param computerStructure
+     */
+    public void visit(ComputerStructure computerStructure) {
+        totalPrice = totalPrice * 0.6;
+    }
+
+    public double getTotalPrice() {
+        return totalPrice;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/CpuComputerNodeImpl.java

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+package com.design.visitor;
+
+/**
+ * 计算机CPU具体节点
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class CpuComputerNodeImpl extends ComputerNode {
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+
+    @Override
+    public double getPrice() {
+        return 1500;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/Main.java

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+package com.design.visitor;
+
+/**
+ * 访问者模式，一个购买组装电脑各种零件，对个人及公司访问者不同优惠的例子
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        // 整个结构对象，也同时充当节点的作用
+        ComputerStructure computerStructure = new ComputerStructure();
+        // 个人购买
+        PersonelVisitorImpl personelVisitor = new PersonelVisitorImpl();
+        computerStructure.accept(personelVisitor);
+        System.out.println(personelVisitor.getTotalPrice());
+        // 公司购买
+        CorpVisitorImpl corpVisitor = new CorpVisitorImpl();
+        computerStructure.accept(corpVisitor);
+        System.out.println(corpVisitor.getTotalPrice());
+    }
+
+}

DesignPattern/src/main/java/com/design/visitor/MemoryComputerNodeImpl.java

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+package com.design.visitor;
+
+/**
+ * 计算机内存条具体节点
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class MemoryComputerNodeImpl extends ComputerNode {
+    @Override
+    public void accept(Visitor visitor) {
+        visitor.visit(this);
+    }
+
+    @Override
+    public double getPrice() {
+        return 500;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/PersonelVisitorImpl.java

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+package com.design.visitor;
+
+/**
+ * 个人访问者，CPU 95折，内存8折，主板9折，其他8折
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public class PersonelVisitorImpl implements Visitor {
+
+    private double totalPrice = 0.0;
+
+    @Override
+    public void visit(CpuComputerNodeImpl cpuComputerNode) {
+        totalPrice = totalPrice + cpuComputerNode.getPrice() * 0.95;
+    }
+
+    @Override
+    public void visit(MemoryComputerNodeImpl memoryComputerNode) {
+        totalPrice = totalPrice + memoryComputerNode.getPrice() * 0.8;
+    }
+
+    @Override
+    public void visit(BoardComputerNodeImpl boardComputerNode) {
+        totalPrice = totalPrice + boardComputerNode.getPrice()* 0.9;
+    }
+
+    /**
+     * 计算机除去CPU内存主板后其他东西的总和
+     *
+     * @param computerStructure
+     */
+    public void visit(ComputerStructure computerStructure) {
+        totalPrice = totalPrice * 0.8;
+    }
+
+    public double getTotalPrice() {
+        return totalPrice;
+    }
+}

DesignPattern/src/main/java/com/design/visitor/Visitor.java

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+package com.design.visitor;
+
+/**
+ * 访问者接口
+ *
+ * @author wliduo[i@dolyw.com]
+ * @date 2023/2/3 17:33
+ */
+public interface Visitor {
+
+    void visit(CpuComputerNodeImpl cpuComputerNode);
+
+    void visit(MemoryComputerNodeImpl memoryComputerNode);
+
+    void visit(BoardComputerNodeImpl boardComputerNode);
+
+    void visit(ComputerStructure computerStructure);
+}