修改实例化关系

yzg-util-base/src/main/java/com/yanzuoguang/util/helper/HttpHelper.java

@@ -250,6 +250,9 @@ public class HttpHelper {
      * @throws IOException
      */
     private static BufferedReader readStream(InputStream stream, StringBuilder result, String charset) throws IOException {
+        if (stream == null) {
+            return null;
+        }
         // 定义BufferedReader输入流来读取URL的响应，设置编码方式
         BufferedReader in = new BufferedReader(new InputStreamReader(stream, charset));
         String line;