diff --git a/src/main.rs b/src/main.rs
index 1dc6417..375410c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,27 +13,31 @@ use crypto::{
 pub const OSS_VERB_GET: &str = "GET";
 
 // https://help.aliyun.com/document_detail/31952.html
-pub struct OSSClient {
-    pub endpoint: String,
-    pub access_key_id: String,
-    pub access_key_secret: String,
+pub struct OSSClient<'a> {
+    pub endpoint: &'a str,
+    pub access_key_id: &'a str,
+    pub access_key_secret: &'a str,
 }
 
-impl OSSClient {
-    pub fn new(endpoint: &str, access_key_id: &str, access_key_secret: &str) -> OSSClient {
+impl<'a> OSSClient<'a> {
+    pub fn new(endpoint: &'a str, access_key_id: &'a str, access_key_secret: &'a str) -> OSSClient<'a> {
         OSSClient {
-            endpoint: endpoint.to_string(),
-            access_key_id: access_key_id.to_string(),
-            access_key_secret: access_key_secret.to_string(),
+            endpoint: endpoint,
+            access_key_id: access_key_id,
+            access_key_secret: access_key_secret,
         }
     }
 
+    pub fn generate_signed_get_url(&self, bucket_name: &str, key: &str, expire_in_seconds: u64) -> String {
+        self.generate_signed_url(OSS_VERB_GET, bucket_name, key, expire_in_seconds, true)
+    }
+
     pub fn generate_signed_url(&self, verb: &str, bucket_name: &str, key: &str, expire_in_seconds: u64, is_https: bool) -> String {
         let mut signed_url = String::new();
         signed_url.push_str(if is_https { "https://" } else { "http://" });
         signed_url.push_str(bucket_name);
         signed_url.push_str(".");
-        signed_url.push_str(self.endpoint.as_str());
+        signed_url.push_str(self.endpoint);
         signed_url.push_str("/");
         signed_url.push_str(key);
     
@@ -43,7 +47,7 @@ impl OSSClient {
         signed_url.push_str("?Expires=");
         signed_url.push_str(expire_secs.to_string().as_str());
         signed_url.push_str("&OSSAccessKeyId=");
-        signed_url.push_str(&urlencoding::encode(self.access_key_id.as_str()));
+        signed_url.push_str(&urlencoding::encode(self.access_key_id));
         signed_url.push_str("&Signature=");
     
         let to_be_signed = get_to_be_signed(verb, expire_secs, bucket_name, key);