我正在遵循谷歌的这篇循序渐进的教程：
https://developers.google.com/+/web/签名/服务器侧流
我已经下载了它提到的Java的GoogleAPI客户端库，并在Eclipse上从Properties>Build Path>Add External Jars添加了Jars。我将所有共同获得的jar文件添加到"libs"文件夹中。
但当我写这行时，在后端代码端，
Oauth2 oauth2 = new Oauth2.Builder(
我无法正确解决进口问题，它说：
Oauth2无法解析为类型
"libs"中包含的jar文件列表为：
谷歌api客户端1.18.0-rc.jar
google-api-client-android-1.18.0-rc.jargoogle-api-client-appengine-1.18.0-rc.jar
谷歌api客户端gson-1.18.0-rc.jar
谷歌api客户端jackson2-1.18.0-rc.jar
google-api-client-java6-1.18.0-rc.jar
谷歌api客户端protobuf-1.18.0-rc.jar
谷歌api客户端服务器-1.18.0-rc.jar
google-api-client-xml-1.18.0-rc.jar google-oauth-client-1.1.80-rc.jar
google-oauth-client-appengine-1.18.0-rc.jar
google-oauth-client-java6-1.18.0-rc.jar
谷歌授权客户端java7-1.18.0-rc.jar
谷歌授权客户端-喷射-1.18.0-rc.jar
谷歌授权客户端服务器-1.18.0-rc.jar
google-http-client-1.1.0-rc.jar谷歌-http-client-android-1.18.0-rc.jar
google-http-client-appengine-1.18.0-rc.jar
google-http-client-protobuf-1.18.0-rc.jar
谷歌-http-客户端-gson-1.18.0-rc.jar
谷歌-http-client-jackson-1.18.0-rc.jar
谷歌-http-client-jackson2-1.18.0-rc.jar
谷歌http-客户端-jdo-1.18.0-rc.jar
谷歌-http-client-xml-1.18.0-rc.jar公共日志-1.1.1.jar
gson-2.1.jar httpclient-4.0.1.jar httpcore-4.0.1.jar
jackson-core-as-1.9.11.jar jackson-re-2.1.3.jar jdo2-pi-2.3-eb.jar
jsr305-1.3.9.jar protobuf-java-2.4.1.jar transaction-api-1.1.jar
xpp3-1.1.4c.jar
有什么想法吗？
谢谢！
您缺少以下jar：
google-oauth-client-1.18.0-rc.jar
google-oauth-client-appengine-1.18.0-rc
google-oauth-client-java6-1.18.0-rc
google-oauth-client-jetty-1.18.0-rc
google-oauth-client-servlet-1.18.0-rc
可以在这里找到：https://developers.google.com/api-client-library/java/apis/oauth2/v2在lib文件夹