diff --git a/index.js b/index.js
index 38e8818..1a23c3d 100644
--- a/index.js
+++ b/index.js
@@ -56,6 +56,15 @@ export default class Response {
     this.#res.end(buf)
   }
 
+  /**
+   * 设置缓存时长, 单位秒
+   */
+  set expires(time = 3600) {
+    let t = new Date(Date.now() + time * 1000)
+    this.set('Expires', t.toGMTString())
+    this.set('Cache-Control', 'max-age=' + time)
+  }
+
   /**
    * [error http 错误显示]
    * @param  {Number} code [http错误码]
@@ -108,7 +117,7 @@ export default class Response {
     data += ''
     data = data || STATUS_TEXT[this.status]
     this.type = 'html'
-    this.set('Content-Length', Buffer.byteLength(data))
+    this.length = Buffer.byteLength(data)
 
     this.body = data
   }
@@ -142,6 +151,8 @@ export default class Response {
       }
     }
 
+    this.expires = 3600
+
     if (Buffer.isBuffer(target)) {
       data = target
     } else {
@@ -156,7 +167,7 @@ export default class Response {
               size = end - start
             }
           }
-          this.set('Content-Length', size)
+          this.length = size
           return fs.origin
             .createReadStream(target, { start, end })
             .pipe(this.#res)
@@ -169,10 +180,27 @@ export default class Response {
       data = data.slice(start, end)
     }
 
-    this.set('Content-Length', data.length)
+    this.length = data.length
     this.body = data
   }
 
+  load(file, type) {
+    let stat = fs.stat(file)
+    if (stat.isFile()) {
+      let size = stat.size
+
+      let _type = type || file.split('.').pop() || 'stream'
+
+      this.expires = 30 * 24 * 3600
+      this.type = _type
+      this.length = stat.size
+      return fs.origin.createReadStream(file).pipe(this.#res)
+    } else {
+      this.status = 404
+      this.body = null
+    }
+  }
+
   /**
    * [send json格式输出]
    * @param  {Num}        code     [返回码]
@@ -196,7 +224,7 @@ export default class Response {
     output = JSON.stringify({ code, msg, data })
 
     this.type = 'json'
-    this.set('Content-Length', Buffer.byteLength(output))
+    this.length = Buffer.byteLength(output)
 
     // 只设置200以上的值
     if (code && code >= 200 && code <= 599) {
diff --git a/package.json b/package.json
index 543484d..b5dbdc9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@gm5/response",
-  "version": "2.0.2",
+  "version": "2.1.0",
   "type": "module",
   "description": "对Http的response进一步封装, 提供常用的API",
   "main": "index.js",