参数校验

src/test/java/com/greenorange/promotion/Client.java

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+package com.greenorange.promotion;
+
+import java.util.Stack;
+
+
+// Command 接口
+interface Command {
+    void execute();  // 执行命令
+    void undo();     // 撤销命令
+}
+
+// Receiver 类，厨师执行具体的菜品制作命令
+class Chef {
+    public void makeBurger() {
+        System.out.println("制作汉堡...");
+    }
+
+    public void makeFriedRice() {
+        System.out.println("制作炒饭...");
+    }
+
+    public void makeFriedChicken() {
+        System.out.println("制作炸鸡...");
+    }
+}
+
+
+// 具体命令类
+class MakeBurgerCommand implements Command {
+    private Chef chef;
+
+    public MakeBurgerCommand(Chef chef) {
+        this.chef = chef;
+    }
+
+    @Override
+    public void execute() {
+        chef.makeBurger();  // 执行命令，制作汉堡
+    }
+
+    @Override
+    public void undo() {
+        System.out.println("撤销汉堡制作命令...");
+    }
+}
+
+class MakeFriedRiceCommand implements Command {
+    private Chef chef;
+
+    public MakeFriedRiceCommand(Chef chef) {
+        this.chef = chef;
+    }
+
+    @Override
+    public void execute() {
+        chef.makeFriedRice();  // 执行命令，制作炒饭
+    }
+
+    @Override
+    public void undo() {
+        System.out.println("撤销炒饭制作命令...");
+    }
+}
+
+class MakeFriedChickenCommand implements Command {
+    private Chef chef;
+
+    public MakeFriedChickenCommand(Chef chef) {
+        this.chef = chef;
+    }
+
+    @Override
+    public void execute() {
+        chef.makeFriedChicken();  // 执行命令，制作炸鸡
+    }
+
+    @Override
+    public void undo() {
+        System.out.println("撤销炸鸡制作命令...");
+    }
+}
+
+
+// 服务员类，接收并执行命令
+class Waiter {
+    private Stack<Command> commandHistory = new Stack<>();  // 用栈来保存历史命令，方便撤销
+
+    public void takeOrder(Command command) {
+        command.execute();  // 执行命令
+        commandHistory.push(command);  // 将命令存入历史记录
+    }
+
+    public void undoLastOrder() {
+        if (!commandHistory.isEmpty()) {
+            Command lastCommand = commandHistory.pop();  // 获取并移除栈顶命令
+            lastCommand.undo();  // 执行撤销操作
+        } else {
+            System.out.println("没有可撤销的命令！");
+        }
+    }
+
+    // 宏命令：一次性下多个菜品
+    public void placeMultipleOrders(Command[] commands) {
+        for (Command command : commands) {
+            takeOrder(command);
+        }
+    }
+}
+
+
+
+// 客户端模拟点餐过程
+public class Client {
+    public static void main(String[] args) {
+        // 创建厨师
+        Chef chef = new Chef();
+
+        // 创建具体命令
+        Command makeBurger = new MakeBurgerCommand(chef);
+        Command makeFriedRice = new MakeFriedRiceCommand(chef);
+        Command makeFriedChicken = new MakeFriedChickenCommand(chef);
+
+        // 创建服务员
+        Waiter waiter = new Waiter();
+
+        // 用户下单
+        waiter.takeOrder(makeBurger);
+        waiter.takeOrder(makeFriedRice);
+
+        // 用户撤销上一条订单（炒饭）
+        waiter.undoLastOrder();
+
+        // 用户一次性下多个菜品（宏命令）
+        Command[] orders = {makeBurger, makeFriedChicken};
+        waiter.placeMultipleOrders(orders);
+    }
+}
+

src/test/java/com/greenorange/promotion/IpDemo.java

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+package com.greenorange.promotion;
+
+import com.alibaba.fastjson.JSONObject;
+import org.junit.jupiter.api.Test;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+
+public class IpDemo {
+
+    public static void main(String[] args) {
+        getIpLocation("123.167.57.119");
+    }
+    public static String getIpLocation(String ip) {
+        try {
+            // 发送请求到ip-api服务
+            String url = "http://ip-api.com/json/" + ip + "?lang=zh-CN"; // 获取中文结果
+            URL obj = new URL(url);
+            HttpURLConnection con = (HttpURLConnection) obj.openConnection();
+            con.setRequestMethod("GET");
+
+            BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
+            String inputLine;
+            StringBuffer response = new StringBuffer();
+
+            while ((inputLine = in.readLine()) != null) {
+                response.append(inputLine);
+            }
+            in.close();
+
+            // 解析JSON返回结果
+            JSONObject jsonResponse = JSONObject.parseObject(response.toString());
+            String country = jsonResponse.getString("country");    // 国家
+            String region = jsonResponse.getString("regionName");  // 省
+            String city = jsonResponse.getString("city");          // 城市
+            System.out.println(jsonResponse);
+            System.out.println(country + "-" + region + "省" + "-" + city);
+            return country + "-" + region + "省" + "-" + city;  // 返回位置
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+        return "未知";
+    }
+
+
+}