添加 w11 URL格式异常与重试工具练习

w11/RetryUtils.java

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+public class RetryUtils {
+    private static final long BASE_WAIT_MS = 500;
+    private static final int MAX_RETRY = 5;
+
+    @FunctionalInterface
+    public interface RetryTask<T> {
+        T execute() throws Exception;
+    }
+
+    public static <T> T retry(RetryTask<T> task) throws Exception {
+        int attempt = 0;
+        while (attempt < MAX_RETRY) {
+            try {
+                return task.execute();
+            } catch (Exception e) {
+                attempt++;
+                if (attempt >= MAX_RETRY) {
+                    System.out.println("最终失败: " + e.getMessage());
+                    throw e;
+                }
+                long waitTime = BASE_WAIT_MS * (1L << attempt);
+                System.out.println("尝试执行 #" + attempt + "... 失败");
+                System.out.println("等待: " + waitTime + "ms");
+                try {
+                    Thread.sleep(waitTime);
+                } catch (InterruptedException ie) {
+                    Thread.currentThread().interrupt();
+                    throw new RuntimeException(ie);
+                }
+            }
+        }
+        throw new IllegalStateException("重试逻辑异常");
+    }
+
+    public static void main(String[] args) throws Exception {
+        RetryUtils.retry(() -> {
+            System.out.println("尝试执行");
+            throw new RuntimeException("模拟失败");
+        });
+    }
+}

w11/UrlFormatException.java

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+import java.util.regex.Pattern;
+
+public class UrlFormatException extends RuntimeException {
+    private final String invalidUrl;
+
+    public UrlFormatException(String message, String invalidUrl) {
+        super(message);
+        this.invalidUrl = invalidUrl;
+    }
+
+    public UrlFormatException(String message, String invalidUrl, Throwable cause) {
+        super(message, cause);
+        this.invalidUrl = invalidUrl;
+    }
+
+    public String getInvalidUrl() {
+        return invalidUrl;
+    }
+}
+
+class UrlValidator {
+    private static final Pattern URL_PATTERN = Pattern.compile("^(https?|http)://[\\w-]+(\\.[\\w-]+)+([\\w.,@?^=%&:/~+#-]*[\\w@?^=%&/~+#-])?$");
+
+    public static void validate(String url) {
+        if (url == null || url.isBlank()) {
+            throw new UrlFormatException("URL不能为空", url);
+        }
+        if (!URL_PATTERN.matcher(url).matches()) {
+            throw new UrlFormatException("URL格式不合法，仅支持http/https协议", url);
+        }
+    }
+
+    public static void main(String[] args) {
+        System.out.println("=== 测试 URL 校验 ===");
+
+        System.out.println("\n空URL校验：");
+        try {
+            UrlValidator.validate(null);
+        } catch (UrlFormatException e) {
+            System.out.println("  异常: " + e.getMessage());
+            System.out.println("  无效URL: " + e.getInvalidUrl());
+        }
+
+        System.out.println("\n非法URL校验：");
+        try {
+            UrlValidator.validate("ftp://example.com");
+        } catch (UrlFormatException e) {
+            System.out.println("  异常: " + e.getMessage());
+            System.out.println("  无效URL: " + e.getInvalidUrl());
+        }
+
+        System.out.println("\n正确URL校验：");
+        try {
+            UrlValidator.validate("https://www.example.com/page");
+            System.out.println("  通过");
+        } catch (UrlFormatException e) {
+            System.out.println("  异常: " + e.getMessage());
+        }
+    }
+}

w11/思考题.txt

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+URL返回404时是否继续重试？如何优化？
+ 
+结论：不应该继续重试。
+ 
+- 404（Not Found）表示资源永久不存在，重试不会改变结果，只会浪费系统资源。
+ 
+优化方案：
+ 
+1. 在重试逻辑中增加状态码判断：将404、401、403等永久失败状态码加入黑名单，遇到这些状态直接终止重试。
+​
+2. 扩展  RetryUtils ：支持可配置的重试条件，如只重试5xx错误、连接超时等临时错误。
+​
+3. 断路器联动：当某个URL连续返回404时，直接将其加入熔断名单，后续请求直接拦截，避免无效调用。
+​
+4. 缓存404结果：对返回404的URL进行本地缓存，一段时间内不再发起请求。