feat: add 30-minute auto-cleanup for generated cache files

src/main/java/com/gmp/mock/service/FileCacheService.java

@@ -4,16 +4,26 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.UUID;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.stereotype.Service;
 
+import jakarta.annotation.PostConstruct;
+import jakarta.annotation.PreDestroy;
+
 /**
  * 文件缓存服务。
  * 生成的文件保存到本地磁盘，通过随机 key 索引，供下载接口使用。
+ * 文件生成 30 分钟后自动清理。
  */
 @Service
 public class FileCacheService {
@@ -21,22 +31,39 @@ public class FileCacheService {
     private static final Logger log = LoggerFactory.getLogger(FileCacheService.class);
 
     private final Path cacheDir;
+    private final Duration expiration;
 
-    public FileCacheService(@Value("${gmp.cache-dir:/tmp/gmp-cache}") String cacheDirPath) {
+    private final ScheduledExecutorService scheduler = Executors.newSingleThreadScheduledExecutor(
+            r -> new Thread(r, "file-cache-cleaner"));
+
+    public FileCacheService(@Value("${gmp.cache-dir:/tmp/gmp-cache}") String cacheDirPath,
+                            @Value("${gmp.cache-expiration:30m}") Duration expiration) {
         this.cacheDir = Path.of(cacheDirPath);
+        this.expiration = expiration;
         try {
             Files.createDirectories(this.cacheDir);
         } catch (IOException e) {
             throw new RuntimeException("无法创建缓存目录: " + cacheDirPath, e);
         }
-        log.info("File cache directory: {}", this.cacheDir.toAbsolutePath());
+        log.info("File cache directory: {}, expiration: {}", this.cacheDir.toAbsolutePath(), this.expiration);
+    }
+
+    @PostConstruct
+    public void startCleanup() {
+        // Initial cleanup on startup
+        cleanExpired();
+        // Schedule periodic cleanup every 5 minutes
+        scheduler.scheduleAtFixedRate(this::cleanExpired, 5, 5, TimeUnit.MINUTES);
+        log.info("Cache cleanup scheduled every 5 minutes");
+    }
+
+    @PreDestroy
+    public void stopCleanup() {
+        scheduler.shutdown();
     }
 
     /**
      * 生成一个随机 key，并将数据写入缓存文件。
-     *
-     * @param data     文件字节数据
-     * @return 随机 key
      */
     public String store(byte[] data) {
         String key = UUID.randomUUID().toString().replace("-", "");
@@ -52,9 +79,6 @@ public class FileCacheService {
 
     /**
      * 根据 key 读取缓存文件。
-     *
-     * @param key 随机 key
-     * @return 文件字节数据，或 null（key 不存在）
      */
     public byte[] retrieve(String key) {
         Path file = cacheDir.resolve(sanitize(key));
@@ -71,10 +95,6 @@ public class FileCacheService {
 
     /**
      * 把缓存文件内容写入输出流。
-     *
-     * @param key  随机 key
-     * @param out  输出流
-     * @return 是否写入成功
      */
     public boolean writeToStream(String key, OutputStream out) throws IOException {
         Path file = cacheDir.resolve(sanitize(key));
@@ -85,6 +105,30 @@ public class FileCacheService {
         return true;
     }
 
+    /**
+     * 清理过期的缓存文件（超过 expiration 时间的文件）。
+     */
+    private void cleanExpired() {
+        try {
+            Instant cutoff = Instant.now().minus(this.expiration);
+            Files.list(cacheDir).forEach(file -> {
+                try {
+                    if (Files.isRegularFile(file)) {
+                        BasicFileAttributes attrs = Files.readAttributes(file, BasicFileAttributes.class);
+                        if (attrs.creationTime().toInstant().isBefore(cutoff)) {
+                            Files.delete(file);
+                            log.debug("Deleted expired cache file: {}", file.getFileName());
+                        }
+                    }
+                } catch (IOException e) {
+                    log.warn("Failed to clean cache file: {}", file.getFileName(), e);
+                }
+            });
+        } catch (IOException e) {
+            log.warn("Cache cleanup failed", e);
+        }
+    }
+
     private String sanitize(String key) {
         return key.replaceAll("[^a-zA-Z0-9\\-_]", "");
     }