change README file

atptro · JacksonTian · commit b43c049a96b0 · 2019-02-21T17:47:53.000+08:00
diff --git a/README.md b/README.md
@@ -42,6 +42,15 @@ For example, with SDK core library latest version and ECS SDK latest version, yo
     <version>[4.16.0,10.0.0)</version>
 </dependency>
 ```
+
+If maven is not downloading jar packages from a central repository, you need to add this dependency in the pom.xml file, or a NoClassDefFoundError exception will be reported
+```xml
+<dependency>
+    <groupId>com.google.code.gson</groupId>
+    <artifactId>gson</artifactId>
+    <version>2.8.5</version>
+</dependency>
+```
 ## Initiate a call
 
 The following code example shows the three main steps to use Alibaba Cloud Java SDK:
diff --git a/README_zh.md b/README_zh.md
@@ -6,6 +6,8 @@
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/aef3826e57ca444fb217bab8edaed195)](https://www.codacy.com/app/aliyun/aliyun-openapi-java-sdk?utm_source=github.com&amp;utm_medium=referral&amp;utm_content=aliyun/aliyun-openapi-java-sdk&amp;utm_campaign=Badge_Grade)
 [![Appveyor Badge](https://ci.appveyor.com/api/projects/status/bymi868y6443gwdp?svg=true)](https://ci.appveyor.com/project/aliyun/aliyun-openapi-java-sdk)
 
+[English document](./README.md)
+
 欢迎使用阿里云开发者工具套件（SDK）。阿里云Java SDK让您不用复杂编程即可访问云服务器、云监控等多个阿里云服务。这里向您介绍如何获取阿里云Java SDK并开始调用。
 如果您在使用 SDK 的过程中遇到任何问题，欢迎前往[阿里云SDK问答社区](https://yq.aliyun.com/tags/type_ask-tagid_23350)提问，提问前请阅读[提问引导](https://help.aliyun.com/document_detail/93957.html)。亦可在当前 GitHub [提交 Issues](https://github.com/aliyun/aliyun-openapi-java-sdk/issues/new)。
 
@@ -31,6 +33,15 @@
     <version>[4.16.0,10.0.0)</version>
 </dependency>
 ```
+
+如果 maven 没有从中央存储库下载 jar 包，则需要将此依赖项添加到`pom.xml`文件中，否则将报告 NoClassDefFoundError 异常
+```xml
+<dependency>
+    <groupId>com.google.code.gson</groupId>
+    <artifactId>gson</artifactId>
+    <version>2.8.5</version>
+</dependency>
+```
 ## 开始调用
 以下这个代码示例向您展示了调用阿里云Java SDK的3个主要步骤：
 1. 创建DefaultAcsClient实例并初始化
