supportLibVersion 的头数字是和targetSdkVersion 版本一样的。
ext {
supportLibVersion = ‘22.2.1‘
}
compile "com.android.support:appcompat-v7:$supportLibVersion"
compile "com.android.support:support-v4:$supportLibVersion"
targetSdkVersion = 22
compileSdkVersion = 22
com.android.support:appcompat-v7 版本号问题
原文：http://www.cnblogs.com/bluestorm/p/6845558.html