上传文件至 'project/command'

project/command/ExitCommand.java

@@ -0,0 +1,19 @@
+package com.crawler.command;
+
+public class ExitCommand extends BaseCommand {
+    @Override
+    public String getName() {
+        return "exit";
+    }
+
+    @Override
+    public String getDescription() {
+        return "退出程序";
+    }
+
+    @Override
+    public void execute() {
+        System.out.println("退出程序...");
+        System.exit(0);
+    }
+}

project/command/HelpCommand.java

@@ -0,0 +1,30 @@
+package com.crawler.command;
+
+import java.util.List;
+
+public class HelpCommand extends BaseCommand {
+    private List<Command> commands;
+
+    public HelpCommand(List<Command> commands) {
+        this.commands = commands;
+    }
+
+    @Override
+    public String getName() {
+        return "help";
+    }
+
+    @Override
+    public String getDescription() {
+        return "显示所有可用指令";
+    }
+
+    @Override
+    public void execute() {
+        System.out.println("可用指令:");
+        System.out.println("---------");
+        for (Command cmd : commands) {
+            System.out.printf("%-8s : %s%n", cmd.getName(), cmd.getDescription());
+        }
+    }
+}

project/command/ListCommand.java

@@ -0,0 +1,34 @@
+package com.crawler.command;
+
+import java.util.List;
+
+public class ListCommand extends BaseCommand {
+    @Override
+    public String getName() {
+        return "list";
+    }
+
+    @Override
+    public String getDescription() {
+        return "查看使用过的指令历史";
+    }
+
+    @Override
+    public void execute() {
+        List<String> historyList = history.getHistory();
+        
+        System.out.println("========================================");
+        System.out.println("指令历史记录:");
+        System.out.println("========================================");
+        
+        if (historyList.isEmpty()) {
+            System.out.println("暂无指令记录");
+        } else {
+            for (int i = 0; i < historyList.size(); i++) {
+                System.out.printf("[%d] %s%n", i + 1, historyList.get(i));
+            }
+        }
+        
+        System.out.println("========================================");
+    }
+}