diff --git a/src/main/java/me/zhyd/oauth/request/AuthAmazonRequest.java b/src/main/java/me/zhyd/oauth/request/AuthAmazonRequest.java
index 30c8c3d..bd91e0b 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthAmazonRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthAmazonRequest.java
@@ -78,7 +78,7 @@ public class AuthAmazonRequest extends AuthDefaultRequest {
      */
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> form = new HashMap<>(8);
+        Map<String, String> form = new HashMap<>(9);
         form.put("grant_type", "authorization_code");
         form.put("code", authCallback.getCode());
         form.put("redirect_uri", config.getRedirectUri());
@@ -95,7 +95,7 @@ public class AuthAmazonRequest extends AuthDefaultRequest {
 
     @Override
     public AuthResponse refresh(AuthToken authToken) {
-        Map<String, String> form = new HashMap<>(6);
+        Map<String, String> form = new HashMap<>(7);
         form.put("grant_type", "refresh_token");
         form.put("refresh_token", authToken.getRefreshToken());
         form.put("client_id", config.getClientId());
diff --git a/src/main/java/me/zhyd/oauth/request/AuthElemeRequest.java b/src/main/java/me/zhyd/oauth/request/AuthElemeRequest.java
index bb2d02e..6471591 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthElemeRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthElemeRequest.java
@@ -45,7 +45,7 @@ public class AuthElemeRequest extends AuthDefaultRequest {
 
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("client_id", config.getClientId());
         form.put("redirect_uri", config.getRedirectUri());
         form.put("code", authCallback.getCode());
@@ -67,13 +67,13 @@ public class AuthElemeRequest extends AuthDefaultRequest {
 
     @Override
     protected AuthUser getUserInfo(AuthToken authToken) {
-        Map<String, Object> parameters = new HashMap<>();
+        Map<String, Object> parameters = new HashMap<>(4);
         // 获取商户账号信息的API接口名称
         String action = "eleme.user.getUser";
         // 时间戳，单位秒。API服务端允许客户端请求最大时间误差为正负5分钟。
         final long timestamp = System.currentTimeMillis();
         // 公共参数
-        Map<String, Object> metasHashMap = new HashMap<>();
+        Map<String, Object> metasHashMap = new HashMap<>(4);
         metasHashMap.put("app_key", config.getClientId());
         metasHashMap.put("timestamp", timestamp);
         String signature = GlobalAuthUtils.generateElemeSignature(config.getClientId(), config.getClientSecret(), timestamp, action, authToken
@@ -118,7 +118,7 @@ public class AuthElemeRequest extends AuthDefaultRequest {
 
     @Override
     public AuthResponse refresh(AuthToken oldToken) {
-        Map<String, String> form = new HashMap<>(2);
+        Map<String, String> form = new HashMap<>(4);
         form.put("refresh_token", oldToken.getRefreshToken());
         form.put("grant_type", "refresh_token");
 
diff --git a/src/main/java/me/zhyd/oauth/request/AuthHuaweiRequest.java b/src/main/java/me/zhyd/oauth/request/AuthHuaweiRequest.java
index 61ead0b..4a9c31b 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthHuaweiRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthHuaweiRequest.java
@@ -47,7 +47,7 @@ public class AuthHuaweiRequest extends AuthDefaultRequest {
      */
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> form = new HashMap<>(5);
+        Map<String, String> form = new HashMap<>(8);
         form.put("grant_type", "authorization_code");
         form.put("code", authCallback.getAuthorization_code());
         form.put("client_id", config.getClientId());
@@ -67,7 +67,7 @@ public class AuthHuaweiRequest extends AuthDefaultRequest {
      */
     @Override
     protected AuthUser getUserInfo(AuthToken authToken) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("nsp_ts", System.currentTimeMillis() + "");
         form.put("access_token", authToken.getAccessToken());
         form.put("nsp_fmt", "JS");
@@ -100,7 +100,7 @@ public class AuthHuaweiRequest extends AuthDefaultRequest {
      */
     @Override
     public AuthResponse refresh(AuthToken authToken) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("client_id", config.getClientId());
         form.put("client_secret", config.getClientSecret());
         form.put("refresh_token", authToken.getRefreshToken());
diff --git a/src/main/java/me/zhyd/oauth/request/AuthJdRequest.java b/src/main/java/me/zhyd/oauth/request/AuthJdRequest.java
index 7b38c71..265d23c 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthJdRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthJdRequest.java
@@ -41,7 +41,7 @@ public class AuthJdRequest extends AuthDefaultRequest {
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
 
-        Map<String, String> params = new HashMap<>(5);
+        Map<String, String> params = new HashMap<>(7);
         params.put("app_key", config.getClientId());
         params.put("app_secret", config.getClientSecret());
         params.put("grant_type", "authorization_code");
@@ -104,7 +104,7 @@ public class AuthJdRequest extends AuthDefaultRequest {
 
     @Override
     public AuthResponse refresh(AuthToken oldToken) {
-        Map<String, String> params = new HashMap<>(5);
+        Map<String, String> params = new HashMap<>(7);
         params.put("app_key", config.getClientId());
         params.put("app_secret", config.getClientSecret());
         params.put("grant_type", "refresh_token");
diff --git a/src/main/java/me/zhyd/oauth/request/AuthMeituanRequest.java b/src/main/java/me/zhyd/oauth/request/AuthMeituanRequest.java
index a171840..4f58a8d 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthMeituanRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthMeituanRequest.java
@@ -35,7 +35,7 @@ public class AuthMeituanRequest extends AuthDefaultRequest {
 
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("app_id", config.getClientId());
         form.put("secret", config.getClientSecret());
         form.put("code", authCallback.getCode());
@@ -55,7 +55,7 @@ public class AuthMeituanRequest extends AuthDefaultRequest {
 
     @Override
     protected AuthUser getUserInfo(AuthToken authToken) {
-        Map<String, String> form = new HashMap<>(3);
+        Map<String, String> form = new HashMap<>(5);
         form.put("app_id", config.getClientId());
         form.put("secret", config.getClientSecret());
         form.put("access_token", authToken.getAccessToken());
@@ -79,7 +79,7 @@ public class AuthMeituanRequest extends AuthDefaultRequest {
 
     @Override
     public AuthResponse refresh(AuthToken oldToken) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("app_id", config.getClientId());
         form.put("secret", config.getClientSecret());
         form.put("refresh_token", oldToken.getRefreshToken());
diff --git a/src/main/java/me/zhyd/oauth/request/AuthTeambitionRequest.java b/src/main/java/me/zhyd/oauth/request/AuthTeambitionRequest.java
index ccb0923..63da04a 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthTeambitionRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthTeambitionRequest.java
@@ -39,7 +39,7 @@ public class AuthTeambitionRequest extends AuthDefaultRequest {
      */
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> form = new HashMap<>(4);
+        Map<String, String> form = new HashMap<>(7);
         form.put("client_id", config.getClientId());
         form.put("client_secret", config.getClientSecret());
         form.put("code", authCallback.getCode());
@@ -90,7 +90,7 @@ public class AuthTeambitionRequest extends AuthDefaultRequest {
         String uid = oldToken.getUid();
         String refreshToken = oldToken.getRefreshToken();
 
-        Map<String, String> form = new HashMap<>(2);
+        Map<String, String> form = new HashMap<>(4);
         form.put("_userId", uid);
         form.put("refresh_token", refreshToken);
         String response = new HttpUtils(config.getHttpConfig()).post(source.refresh(), form, false);
diff --git a/src/main/java/me/zhyd/oauth/request/AuthTwitterRequest.java b/src/main/java/me/zhyd/oauth/request/AuthTwitterRequest.java
index abb6c56..7275a3c 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthTwitterRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthTwitterRequest.java
@@ -102,7 +102,7 @@ public class AuthTwitterRequest extends AuthDefaultRequest {
         httpHeader.add("Authorization", header);
         httpHeader.add(Constants.CONTENT_TYPE, "application/x-www-form-urlencoded");
 
-        Map<String, String> form = new HashMap<>(1);
+        Map<String, String> form = new HashMap<>(3);
         form.put("oauth_verifier", authCallback.getOauth_verifier());
         String response = new HttpUtils(config.getHttpConfig()).post(source.accessToken(), form, httpHeader, false);
 
@@ -118,7 +118,7 @@ public class AuthTwitterRequest extends AuthDefaultRequest {
 
     @Override
     protected AuthUser getUserInfo(AuthToken authToken) {
-        Map<String, String> queryParams = new HashMap<>();
+        Map<String, String> queryParams = new HashMap<>(5);
         queryParams.put("user_id", authToken.getUserId());
         queryParams.put("screen_name", authToken.getScreenName());
         queryParams.put("include_entities", Boolean.toString(true));
@@ -162,7 +162,7 @@ public class AuthTwitterRequest extends AuthDefaultRequest {
     }
 
     private Map<String, String> buildOauthParams() {
-        Map<String, String> params = new HashMap<>(5);
+        Map<String, String> params = new HashMap<>(12);
         params.put("oauth_consumer_key", config.getClientId());
         params.put("oauth_nonce", GlobalAuthUtils.generateNonce(32));
         params.put("oauth_signature_method", "HMAC-SHA1");
diff --git a/src/main/java/me/zhyd/oauth/request/AuthXmlyRequest.java b/src/main/java/me/zhyd/oauth/request/AuthXmlyRequest.java
index 9c6e1cf..023375d 100644
--- a/src/main/java/me/zhyd/oauth/request/AuthXmlyRequest.java
+++ b/src/main/java/me/zhyd/oauth/request/AuthXmlyRequest.java
@@ -43,7 +43,7 @@ public class AuthXmlyRequest extends AuthDefaultRequest {
      */
     @Override
     protected AuthToken getAccessToken(AuthCallback authCallback) {
-        Map<String, String> map = new HashMap<>(6);
+        Map<String, String> map = new HashMap<>(9);
         map.put("code", authCallback.getCode());
         map.put("client_id", config.getClientId());
         map.put("client_secret", config.getClientSecret());
diff --git a/src/main/java/me/zhyd/oauth/utils/GlobalAuthUtils.java b/src/main/java/me/zhyd/oauth/utils/GlobalAuthUtils.java
index be0e7c3..7d4a9f2 100644
--- a/src/main/java/me/zhyd/oauth/utils/GlobalAuthUtils.java
+++ b/src/main/java/me/zhyd/oauth/utils/GlobalAuthUtils.java
@@ -101,15 +101,18 @@ public class GlobalAuthUtils {
      * @return map
      */
     public static Map<String, String> parseStringToMap(String accessTokenStr) {
-        Map<String, String> res = new HashMap<>(6);
+        Map<String, String> res = null;
         if (accessTokenStr.contains("&")) {
             String[] fields = accessTokenStr.split("&");
+            res = new HashMap<>((int) (fields.length / 0.75 + 1));
             for (String field : fields) {
                 if (field.contains("=")) {
                     String[] keyValue = field.split("=");
                     res.put(GlobalAuthUtils.urlDecode(keyValue[0]), keyValue.length == 2 ? GlobalAuthUtils.urlDecode(keyValue[1]) : null);
                 }
             }
+        } else {
+            res = new HashMap<>(0);
         }
         return res;
     }