Error:(26, 13) Failed to resolve: com.squareup.picasso:picasso:2.5.2 的解决

前几天跟着教程学RecyclerView 的时候，android studio 的build.gradle死活不能将com.squareup.picasso:picasso:2.5.2 编译过，一直报错，网上找来的方法大多是说加上

代码：

repositories {
jcenter()
mavenCentral()
}

clean project后仍没有效果，然后在多次尝试中突然它爆出错误说：

Could not resolve all dependencies for configuration ':app:_debug Could not resolve com.squareup.picasso:picasso:2.5.2.      Required by:          floatbutton:app:unspecified       > No cached version of com.squareup.picasso:picasso:2.5.2 available for offline mode.       > No cached version of com.squareup.picasso:picasso:2.5.2 available for offline mode.       > No cached version of com.squareup.picasso:picasso:2.5.2 available for offline mode.

咦，然后我就把 File->Settings->Build,Execution,Deployment->Gradle 右边的Offline work的勾取消掉了，Clean 了一下项目，并且设置了 repositories

然后出现了：`Error:A problem occurred configuring project ‘:app’.

Could not resolve all dependencies for configuration ‘:app:_debugCompile’.

Could not resolve com.mcxiaoke.volley:library:1.0.18.

Required by:

udacity-android-nanodegree–july2015-project1:app:unspecified

Could not GET ‘https://jcenter.bintray.com/com/mcxiaoke/volley/library/1.0.18/library-1.0.18.pom‘.

Connection to https://jcenter.bintray.com refused

Could not GET ‘https://repo1.maven.org/maven2/com/mcxiaoke/volley/library/1.0.18/library-1.0.18.pom‘.

Connection to https://repo1.maven.org refused

额。。。。猜测大概是https:的锅，然后改为

repositories {
maven {
url "http://repo1.maven.org/maven2"
}
}

万岁，成功了

写这么多是因为，在查到的资料里，这里提到的每一步都有人成功解决这个问题，我的方法肯定不是最好的。但我直到最后一步才解决，所以我都记录下来了

相关链接：AndroidStudio创造TV-APP，出现Error:(28, 13) Failed to resolve: com.squareup.picasso:picasso:2.5.0 的解决，这位博主用了另一种方法解决