task-77: 统一 Coze、品牌检查和紫鸟 HTTP 客户端的连接复用策略

backend-java/src/main/java/com/nanri/aiimage/config/HttpClientPool.java

@@ -0,0 +1,45 @@
+package com.nanri.aiimage.config;
+
+import org.springframework.http.client.ClientHttpRequestFactory;
+import org.springframework.http.client.JdkClientHttpRequestFactory;
+
+import java.net.http.HttpClient;
+import java.time.Duration;
+
+/**
+ * Task 77：外部 HTTP 客户端统一连接复用池。
+ * Coze / 品牌检查 / 紫鸟三个外部客户端共用同一个 java.net.http.HttpClient
+ * （内置 keep-alive 连接池），避免各自新建短命客户端导致连接无法复用、
+ * 每次请求都重新建连。各客户端按自身超时创建独立的
+ * JdkClientHttpRequestFactory（共享底层连接池），RestClient 单例懒加载。
+ */
+public class HttpClientPool {
+
+    private static volatile HttpClient sharedHttpClient;
+
+    /** 共享连接池实例：单一 HttpClient 承载全部外部调用的连接复用。 */
+    public static HttpClient sharedHttpClient() {
+        HttpClient client = sharedHttpClient;
+        if (client != null) {
+            return client;
+        }
+        synchronized (HttpClientPool.class) {
+            if (sharedHttpClient == null) {
+                sharedHttpClient = HttpClient.newBuilder()
+                        .connectTimeout(Duration.ofSeconds(10))
+                        .version(HttpClient.Version.HTTP_1_1)
+                        .build();
+            }
+            return sharedHttpClient;
+        }
+    }
+
+    /** 按 readTimeout（毫秒）创建共享连接池工厂；非法值钳制到最小正数。 */
+    public static ClientHttpRequestFactory requestFactory(int readTimeoutMillis) {
+        int safeReadTimeout = Math.max(1, readTimeoutMillis);
+        JdkClientHttpRequestFactory factory =
+                new JdkClientHttpRequestFactory(sharedHttpClient());
+        factory.setReadTimeout(Duration.ofMillis(safeReadTimeout));
+        return factory;
+    }
+}