fix the code error

Author: jemygraw

docs/rtc/README.md

@@ -6,7 +6,7 @@
     - [x] 创建房间: client->createApp()
     - [x] 查看房间: client->getApp()
     - [x] 删除房间: client->deleteApp()
-    - [x] 生成房间token: client->AppToken()
+    - [x] 生成房间token: client->appToken()
 
 
 
@@ -32,7 +32,7 @@
 $ak = "gwd_gV4gPKZZsmEOvAuNU1AcumicmuHooTfu64q5";
 $sk = "xxxx";
 $auth = new Auth($ak, $sk);
-$client = new QiniuRtc\AppClient($auth);
+$client = new Qiniu\Rtc\AppClient($auth);
 $resp=$client->createApp("901","testApp");
 print_r($resp);
 ```
@@ -43,7 +43,7 @@ print_r($resp);
 $ak = "gwd_gV4gPKZZsmEOvAuNU1AcumicmuHooTfu64q5";
 $sk = "xxxx";
 $auth = new Auth($ak, $sk);
-$client = new QiniuRtc\AppClient($auth);
+$client = new Qiniu\Rtc\AppClient($auth);
 $resp=$client->getApp("deq02uhb6");
 print_r($resp);
 ```
@@ -54,7 +54,7 @@ print_r($resp);
 $ak = "gwd_gV4gPKZZsmEOvAuNU1AcumicmuHooTfu64q5";
 $sk = "xxxx";
 $auth = new Auth($ak, $sk);
-$client = new QiniuRtc\AppClient($auth);
+$client = new Qiniu\Rtc\AppClient($auth);
 $resp=$client->deleteApp("deq02uhb6");
 print_r($resp);
 ```
@@ -65,7 +65,7 @@ print_r($resp);
 $ak = "gwd_gV4gPKZZsmEOvAuNU1AcumicmuHooTfu64q5";
 $sk = "xxxx";
 $auth = new Auth($ak, $sk);
-$client = new QiniuRtc\AppClient($auth);
+$client = new Qiniu\Rtc\AppClient($auth);
 $resp=$client->appToken("deq02uhb6", "lfx", '1111', (time()+3600), 'user');
 print_r($resp);
 ```

src/Qiniu/Rtc/AppClient.php

@@ -138,7 +138,7 @@ public function listActiveRooms($appId, $prefix = null, $offset = null, $limit =
         if (isset($limit)) {
             $query['limit'] = $limit;
         }
-        if ($query != null) {
+        if (isset($query) && !empty($query)) {
             $query = '?' . http_build_query($query);
             $url = sprintf("%s/%s/rooms%s", $this->baseURL, $appId, $query);
         } else {
@@ -170,7 +170,7 @@ public function appToken($appId, $roomName, $userId, $expireAt, $permission)
 
     private function get($url, $cType = null)
     {
-        $rtcToken = $this->auth->authorizationV2($url, "GET", $body, $cType);
+        $rtcToken = $this->auth->authorizationV2($url, "GET", null, $cType);
         $rtcToken['Content-Type'] = $cType;
         $ret = Client::get($url, $rtcToken);
         if (!$ret->ok()) {
@@ -179,21 +179,21 @@ private function get($url, $cType = null)
         return array($ret->json(), null);
     }
 
-    private function delete($url, $cType = 'application/json')
+    private function delete($url, $contentType = 'application/json')
     {
-        $rtcToken = $this->auth->authorizationV2($url, "DELETE", $body, $cType);
-        $rtcToken['Content-Type'] = $cType;
+        $rtcToken = $this->auth->authorizationV2($url, "DELETE", null, $contentType);
+        $rtcToken['Content-Type'] = $contentType;
         $ret = Client::delete($url, $rtcToken);
         if (!$ret->ok()) {
             return array(null, new Error($url, $ret));
         }
         return array($ret->json(), null);
     }
 
-    private function post($url, $body, $cType = 'application/json')
+    private function post($url, $body, $contentType = 'application/json')
     {
-        $rtcToken = $this->auth->authorizationV2($url, "POST", $body, $cType);
-        $rtcToken['Content-Type'] = $cType;
+        $rtcToken = $this->auth->authorizationV2($url, "POST", $body, $contentType);
+        $rtcToken['Content-Type'] = $contentType;
         $ret = Client::post($url, $body, $rtcToken);
         if (!$ret->ok()) {
             return array(null, new Error($url, $ret));