spring增强访问者模式-改造前（early binding）

.idea/compiler.xml

@@ -2,6 +2,7 @@
 <project version="4">
   <component name="CompilerConfiguration">
     <annotationProcessing>
+      <profile default="true" name="Default" enabled="true" />
       <profile name="Maven default annotation processors profile" enabled="true">
         <sourceOutputDir name="target/generated-sources/annotations" />
         <sourceTestOutputDir name="target/generated-test-sources/test-annotations" />

src/main/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/DrawService.java

@@ -0,0 +1,33 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring;
+
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.Building;
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.Factory;
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.Node;
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.School;
+
+/**
+ * 新需求：需要加入绘制Node功能
+ * Node接口作为衔接组件的桥梁，应该尽可能保持稳定，不应频繁更改。
+ * 定义一个新的类DrawService，把所有的draw逻辑都写在这里面
+ *
+ * @author F嘉阳
+ * @date 2022/1/26 10:18
+ */
+public class DrawService {
+
+	public void draw(Building building) {
+		System.out.println("draw building");
+	}
+
+	public void draw(Factory factory) {
+		System.out.println("draw factory");
+	}
+
+	public void draw(School school) {
+		System.out.println("draw school");
+	}
+
+	public void draw(Node node) {
+		System.out.println("draw node");
+	}
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/bean/Building.java

@@ -0,0 +1,19 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean;
+
+/**
+ * TODO:
+ *
+ * @author F嘉阳
+ * @date 2022/1/26 10:18
+ */
+public class Building implements Node {
+	@Override
+	public String getName() {
+		return null;
+	}
+
+	@Override
+	public String getDescription() {
+		return null;
+	}
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/bean/Factory.java

@@ -0,0 +1,19 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean;
+
+/**
+ * TODO:
+ *
+ * @author F嘉阳
+ * @date 2022/1/26 10:18
+ */
+public class Factory implements Node {
+	@Override
+	public String getName() {
+		return null;
+	}
+
+	@Override
+	public String getDescription() {
+		return null;
+	}
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/bean/Node.java

@@ -0,0 +1,14 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean;
+
+/**
+ * 地图节点
+ *
+ * @author F嘉阳
+ * @date 2022/1/26 10:17
+ */
+public interface Node {
+
+	String getName();
+
+	String getDescription();
+}

src/main/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/bean/School.java

@@ -0,0 +1,19 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean;
+
+/**
+ * TODO:
+ *
+ * @author F嘉阳
+ * @date 2022/1/26 10:18
+ */
+public class School implements Node {
+	@Override
+	public String getName() {
+		return null;
+	}
+
+	@Override
+	public String getDescription() {
+		return null;
+	}
+}

src/test/java/top/fjy8018/designpattern/pattern/behavior/visitor/spring/DrawServiceTest.java

@@ -0,0 +1,32 @@
+package top.fjy8018.designpattern.pattern.behavior.visitor.spring;
+
+import lombok.extern.slf4j.Slf4j;
+import org.junit.jupiter.api.Test;
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.Factory;
+import top.fjy8018.designpattern.pattern.behavior.visitor.spring.bean.Node;
+
+/**
+ * DrawService中只有4个draw方法，参数类型分别是Factory, Building, School和Node，如果调用方传了一个City进来怎么办？
+ * 毕竟调用方可以自己实现一个City类传进来。这种情况下程序该调用什么方法呢？
+ * 我们没有draw(City)方法，为了防止这种情况发生，程序在编译阶段就直接选择使用DrawService::draw(Node)方法。
+ * 无论调用方传了什么实现进来，我们都统一使用DrawService::draw(Node)方法以确保程序安全运行。
+ * 在编译时（而不是运行时）决定调用哪个方法，这就叫做Static/Early Binding。
+ * 这也就解释了我们为什么输出了 draw node 。
+ */
+@Slf4j
+class DrawServiceTest {
+
+	/**
+	 * 输出：draw node
+	 */
+	@Test
+	public void draw() {
+		draw(new Factory());
+	}
+
+	private void draw(Node node) {
+		DrawService drawService = new DrawService();
+		drawService.draw(node);
+	}
+
+}