trae1/ChallengeMiddlewarePipeline.java

import java.util.ArrayList;
import java.util.List;

// 请求处理接口
interface HttpRequestHandler {
    void handle(HttpRequest request);
}

// 基础处理器
class CoreHandler implements HttpRequestHandler {
    public void handle(HttpRequest request) {
        System.out.println("Core processing: " + request.getPath());
    }
}

// 装饰器抽象类
abstract class MiddlewareDecorator implements HttpRequestHandler {
    protected HttpRequestHandler nextHandler;

    public MiddlewareDecorator(HttpRequestHandler handler) {
        this.nextHandler = handler;
    }
}

// 具体装饰器实现
class AuthMiddleware extends MiddlewareDecorator {
    public AuthMiddleware(HttpRequestHandler handler) {
        super(handler);
    }

    public void handle(HttpRequest request) {
        if (!request.getHeaders().containsKey("Authorization")) {
            throw new SecurityException("Unauthorized");
        }
        nextHandler.handle(request);
    }
}

class LoggingMiddleware extends MiddlewareDecorator {
    public LoggingMiddleware(HttpRequestHandler handler) {
        super(handler);
    }

    public void handle(HttpRequest request) {
        System.out.println("Request logged: " + request.getMethod());
        nextHandler.handle(request);
    }
}

// 请求对象
class HttpRequest {
    private String method;
    private String path;
    private List<String> headers = new ArrayList<>();

    public HttpRequest(String method, String path) {
        this.method = method;
        this.path = path;
    }

    public void addHeader(String header) {
        headers.add(header);
    }

    // getters...
}

// 管道构建器
class MiddlewarePipeline {
    private HttpRequestHandler pipeline;

    public void addMiddleware(HttpRequestHandler middleware) {
        if (pipeline == null) {
            pipeline = middleware;
        } else {
            // 找到最后一个处理器并添加新装饰器
            HttpRequestHandler current = pipeline;
            while (current instanceof MiddlewareDecorator) {
                MiddlewareDecorator decorator = (MiddlewareDecorator) current;
                if (decorator.nextHandler == null) {
                    decorator.nextHandler = middleware;
                    break;
                }
                current = decorator.nextHandler;
            }
        }
    }

    public void execute(HttpRequest request) {
        if (pipeline != null) {
            pipeline.handle(request);
        }
    }
}

// 客户端使用
public class ChallengeMiddlewarePipeline {
    public static void main(String[] args) {
        MiddlewarePipeline pipeline = new MiddlewarePipeline();
        
        // 构建处理链（顺序重要）
        pipeline.addMiddleware(new LoggingMiddleware(null));
        pipeline.addMiddleware(new AuthMiddleware(new CoreHandler()));
        
        // 执行请求
        HttpRequest request = new HttpRequest("GET", "/api/data");
        request.addHeader("Authorization: Bearer token123");
        
        pipeline.execute(request);
    }
}