在android studio中构建android云端点时出错：请确保已安装JDK

我正在尝试将后端端点云模块添加到我的android studio应用程序中，但当我尝试构建项目时，出现以下错误：

Executing tasks: [:backend:compileJava, :mobile:compileDebugSources, :wear:compileDebugSources]

Configuration on demand is an incubating feature.
:backend:compileJava FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':backend:compileJava'.
> Cannot find System Java Compiler. Ensure that you have installed a JDK (not just a JRE) and configured your JAVA_HOME system variable to point to the according directory.

我将JDK设置为1.7（项目结构>SDK位置>JDK位置：/Library/Java/JavaVirtualMachines/jdk1.7.0_45.JDK/Contents/Home），但仍然收到此错误

我甚至试图通过将此添加到我的gradle.properties和local.properties来强制JDK定位，但没有成功： org.gradle.java.home=/Library/java/JavaVirtualMachines/jdk1.7.0_45.jdk/Contents/home

Android Studio版本：1.1.0

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Gradle版本：2.2.1

问题在于，yosemite安装程序将重复的java jar文件复制到/Library/java/Extensions中。删除jar文件并重新启动android studio修复了它：

cd /Library/Java/Extensions 
sudo rm -rf *.jar