jclouds 是一个开源的Java类库，用来帮你开始云计算应用开发，并可重用已有的Java和Clojure技能。该API提供云计算环境的可移植抽象层以及云规范特性，支持包括 Amazon, VMWare, Azure, and Rackspace 等云计算平台。

1. Simple interface Instead of creating new object types, we reuse concepts like maps so that the programming model is familiar. In this way, you can get started without dealing with REST-like apis or WS.
2. Runtime portability We have drivers that allow you to operate in restricted environments like Google App Engine. We have very few required dependencies, so we are unlikely to clash with your app.
3. Deal with web complexity Network based computing introduces issues such as transient failures and redirects. We handle this for you.
4. Unit testability Writing tests for cloud endpoints is difficult. We provide you with Stub connections that simulate a cloud without creating network connections. In this way, you can write your unit tests without mocking complexity or the brittleness of remote connections.
5. Performance We perform tasks in parallel for you wherever possible and use straight sax for xml. If you need even more speed, you can plugin our enterprise driver.
6. Location All of our abstractions are location-aware. For example, you can get ISO-3166 codes to tell which country or province a cloud runs in.
7. Quality We test every provider with live scenarios before each release. If it doesn't pass, the provider goes into the sandbox.

项目主页：http://www.open-open.com/lib/view/home/1339255231928