package org.codelibs.fess.crawler.client.http;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.codelibs.fess.crawler.client.CrawlerClient;
import org.codelibs.fess.crawler.client.FaultTolerantClient;

/**
 * SwitchableHttpClient is a switchable HTTP client that can use either Apache HttpComponents 4.x or 5.x.
 * The client implementation is selected based on the system property {@code fess.crawler.http.client}.
 *

**Resource Management**: `AutoCloseable` throughout, `DeferredFileOutputStream` for large responses, connection pooling, background temp file deletion via `FileUtil.deleteInBackground()`

**Fault Tolerance**: `FaultTolerantClient` wrapper (retry, circuit breaker), `SwitchableHttpClient` for HTTP client fallback

---

## Key Components

### Core Classes