add factory pattern

Author: jarry

factory-pattern/README.md

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+# 简介
+简单工厂模式是一种创建型设计模式， 由工厂类提供统一的创建对象的方法，将对象实例化与使用分离开。
+
+# 实现步骤
+1. 建立一个产品接口类或抽象类。
+2. 新建多个具体产品类，均实现该产品接口类。
+3. 建立一个工厂类，提供按类型实例化具体产品类的方法，返回抽象接口类型。
+4. 想要获取具体产品对象时，调用工厂方法来实例化，并由调用方来确定对象的类型。
+
+# 作用
+- 对象创建和调用解耦，便于实例化时进行统一干预和修改。
+- 屏蔽复杂的对象创建逻辑，交由统一的工厂方法。
+- 采用统一的方式来实例化，还可以防止内存中实例对象不断增多。

factory-pattern/java/src/Bus.java

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+package src;
+public class Bus implements Vehicle {
+ 
+  @Override
+  public void run() {
+     System.out.println("Bus::run().");
+  }
+}

factory-pattern/java/src/Car.java

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+package src;
+public class Car implements Vehicle {
+ 
+  @Override
+  public void run() {
+     System.out.println("Car::run().");
+  }
+}

factory-pattern/java/src/Motorcycle.java

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+package src;
+public class Motorcycle implements Vehicle {
+ 
+  @Override
+  public void run() {
+     System.out.println("Motorcycle::run().");
+  }
+}

factory-pattern/java/src/Van.java

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+package src;
+public class Van implements Vehicle {
+ 
+  @Override
+  public void run() {
+     System.out.println("Van::run().");
+  }
+}

factory-pattern/java/src/Vehicle.java

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+package src;
+public interface Vehicle {
+  void run();
+  // void horn();
+}

factory-pattern/java/src/VehicleFactory.java

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+package src;
+
+/*
+  意图：定义基础接口，让其子类自己决定实例化哪一个工厂类，工厂模式使其创建过程延迟到子类进行。
+  主要作用：解决接口选择的问题。统一实例化，用接口来实例化类更加抽象。
+  何时使用：大量构造函数的地方，调用了大量的new来实例化类。
+  如何解决：让其子类实现工厂接口，返回的也是一个抽象的产品。
+ */
+public class VehicleFactory {
+  public Vehicle getVehicle(VehicleType type) {
+    switch (type) {
+      case BUS:
+        return new Bus();
+      case CAR:
+        return new Car();
+      case MOTORCYCLE:
+        return new Motorcycle();
+      case VAN:
+        return new Van();
+      default:
+        return null;
+    }
+
+  }
+}

factory-pattern/java/src/VehicleType.java

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+package src;
+
+public enum VehicleType {
+  BUS("bus", 1),
+  CAR("car", 2),
+  MOTORCYCLE("motorcycle", 3),
+  VAN("van", 4);
+
+  private String name;
+  private int index;
+
+  public static String getName(int index) {
+    VehicleType values[] = VehicleType.values();
+    for (int i = 0; i < values.length; i++) {
+      if (values[i].getIndex() == index) {
+        return values[i].getName();
+      }
+    }
+    return null;
+  }
+
+  private VehicleType(String name, int index) {
+    this.name = name;
+    this.index = index;
+  }
+
+  public String getName() {
+    return name;
+  }
+
+  public void setName(String name) {
+    this.name = name;
+  }
+
+  public int getIndex() {
+    return index;
+  }
+
+  public void setIndex(int index) {
+    this.index = index;
+  }
+}

factory-pattern/java/test/Test.java

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+package test;
+
+import src.*;
+
+public class Test {
+
+  public static void start() {
+    VehicleFactory vehicleFactory = new VehicleFactory();
+
+    // 获取Bus对象，并调用它的 run 方法
+    Vehicle bus = vehicleFactory.getVehicle(VehicleType.BUS);
+    bus.run();
+
+    // 获取Car对象，并调用它的 run 方法
+    Vehicle car = vehicleFactory.getVehicle(VehicleType.CAR);
+    // 类型转为Car
+    Car car1 = (Car)car;
+    car1.run();
+
+    // 获取Motorcycle对象，并调用它的 run 方法
+    // 类型直接转为Motorcycle
+    Motorcycle motorcycle = (Motorcycle)vehicleFactory.getVehicle(VehicleType.MOTORCYCLE);
+    motorcycle.run();
+
+    // 获取Motorcycle对象，并调用它的 run 方法
+    Vehicle van = vehicleFactory.getVehicle(VehicleType.VAN);
+    van.run();
+
+  }
+  public static void main(String[] args) {
+    System.out.println("test start:");
+    start();
+  }
+
+}
+
+/**
+ * 测试
+jarry@jarrys-MacBook-Pro java % java --version
+java 14.0.1 2020-04-14
+Java(TM) SE Runtime Environment (build 14.0.1+7)
+Java HotSpot(TM) 64-Bit Server VM (build 14.0.1+7, mixed mode, sharing)
+
+jarry@jarrys-MacBook-Pro java % javac test/Test.java 
+jarry@jarrys-MacBook-Pro java % java test/Test 
+test start:
+Bus::run().
+Car::run().
+Motorcycle::run().
+Van::run().
+ */

factory-pattern/js/package.json

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+{
+  "name": "esm-project",
+  "version": "1.0.0",
+  "main": "test/test.js",
+  "scripts": {
+    "test": "node test/test.js"
+  },
+  "type": "module"
+}

factory-pattern/js/src/Bus.js

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+import { Vehicle } from './Vehicle.js'
+export class Bus extends Vehicle {
+  constructor(options) {
+    super(options)
+  }
+  run() {
+    console.log('Bus::run().')
+  }
+}

factory-pattern/js/src/Car.js

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+import { Vehicle } from './Vehicle.js'
+export class Car extends Vehicle {
+	constructor(options) {
+		super(options)
+	}
+	run() {
+		console.log('Car::run().')
+	}
+}

factory-pattern/js/src/Motorcycle.js

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+import { Vehicle } from './Vehicle.js'
+export class Motorcycle extends Vehicle {
+  constructor(options) {
+    super(options)
+  }
+  run() {
+    console.log('Motorcycle::run().')
+  }
+}

factory-pattern/js/src/Van.js

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+import { Vehicle } from './Vehicle.js'
+export class Van extends Vehicle {
+  constructor(options) {
+    super(options)
+  }
+  run() {
+    console.log('Van::run().')
+  }
+}

factory-pattern/js/src/Vehicle.js

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+export class Vehicle {
+	constructor(options) {
+		// console.log('Vehicle::init()')
+	}
+	run() {
+		console.log('Vehicle::run()')
+	}
+}

factory-pattern/js/src/VehicleFactory.js

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+import { Bus } from './Bus.js'
+import { Car } from './Car.js'
+import { Motorcycle } from './Motorcycle.js'
+import { Van } from './Van.js'
+export const VehicleType = {
+  BUS: 'bus',
+  CAR: 'car',
+  MOTORCYCLE: 'motorcycle',
+  VAN: 'van',
+}
+export class VehicleFactory {
+  getVehicle(type, options) {
+    switch (type) {
+      case 'bus':
+        return new Bus(options)
+      case 'car':
+        return new Car(options)
+      case 'motorcycle':
+        return new Motorcycle(options)
+      case 'van':
+        return new Van(options)
+      default:
+        return undefined
+    }
+  }
+}

factory-pattern/js/test/test.html

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+<script type="module">
+// module need run in http server
+import { test } from './test.js'
+alert('pls look console info.' + '\n\r' + test)
+</script>

factory-pattern/js/test/test.js

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+import { VehicleFactory, VehicleType } from '../src/VehicleFactory.js'
+
+export function test() {
+  const vehicleFactory = new VehicleFactory()
+
+  // 获取Bus对象，并调用它的 run 方法
+  const bus = vehicleFactory.getVehicle(VehicleType.BUS)
+  bus.run()
+
+  // 获取Car对象，并调用它的 run 方法
+  const car = vehicleFactory.getVehicle(VehicleType.CAR)
+  car.run()
+
+  // 获取Motorcycle对象，并调用它的 run 方法
+  const motorcycle = vehicleFactory.getVehicle(VehicleType.MOTORCYCLE)
+  motorcycle.run()
+
+  // 获取Motorcycle对象，并调用它的 run 方法
+  const van = vehicleFactory.getVehicle(VehicleType.VAN)
+  van.run()
+}
+
+// 执行测试
+;(function () {
+  console.log('test start:')
+  test()
+})()
+/**
+jarry@jarrys-MacBook-Pro js % node --version
+v16.15.1
+ */
+/*
+// node run
+jarry@jarrys-MacBook-Pro js % node -v
+v16.15.1
+jarry@jarrys-MacBook-Pro js % node test/test.js
+test start:
+Bus::run().
+Car::run().
+Motorcycle::run().
+Van::run().
+*/
+
+/*
+// npm run
+jarry@jarrys-MacBook-Pro js % npm run test
+
+> [email protected] test
+> node test/test.js
+
+test start:
+Bus::run().
+Car::run().
+Motorcycle::run().
+Van::run().
+*/
+
+/**
+// n run
+jarry@jarrys-MacBook-Pro js % n run 14.17.0 test/test.js
+test start:
+Bus::run().
+Car::run().
+Motorcycle::run().
+Van::run().
+*/
+
+/*
+// node 10.24.1 isn't support es module
+// Node 13.2.0 can support ES Modules
+jarry@jarrys-MacBook-Pro js % n run 10.24.1 test/test.js
+/Users/jarry/github/design-pattern/factory-pattern/js/test/test.js:1
+import { VehicleFactory, VehicleType } from '../src/VehicleFactroy.js'
+       ^
+
+SyntaxError: Unexpected token {
+    at Module._compile (internal/modules/cjs/loader.js:723:23)
+    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
+    at Module.load (internal/modules/cjs/loader.js:653:32)
+    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
+    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
+    at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
+    at startup (internal/bootstrap/node.js:283:19)
+    at bootstrapNodeJSCore (internal/bootstrap/node.js:623:3)
+jarry@jarrys-MacBook-Pro js %
+*/

factory-pattern/python/src/Bus.py

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+from Vehicle import Vehicle
+class Bus(Vehicle):
+  def run(self):
+    print("Bus::run()")
+

factory-pattern/python/src/Car.py

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+from Vehicle import Vehicle
+class Car(Vehicle):
+  def run(self):
+    print("Car::run()")

factory-pattern/python/src/Motorcycle.py

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+from Vehicle import Vehicle
+class Motorcycle(Vehicle):
+  def run(self):
+    print("Motorcycle::run()")

factory-pattern/python/src/Van.py

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+from Vehicle import Vehicle
+class Van(Vehicle):
+  def run(self):
+    print("Van::run()")