在cordova项目打包时，有时候处在公司内网环境，导致有些文件无法下载报下面的错误：
A problem occurred configuring root project 'android'.
> Could not resolve all dependencies for configuration ':classpath'.
> Could not resolve com.android.tools.build:gradle:2.2.3.
Required by:
project :
> Could not resolve com.android.tools.build:gradle:2.2.3.
> Could not get resource 'https://jcenter.bintray.com/com/android/tools/build/gradle/2.2.3/gradle-2.2.3.pom'.
> Could not GET 'https://jcenter.bintray.com/com/android/tools/build/gradle/2.2.3/gradle-2.2.3.pom'.
> Connect to jcenter.bintray.com:443 [jcenter.bintray.com/35.165.178.167, jcenter.bintray.com/52.89.158.216] failed: Connection timed out: connect
> Could not resolve com.android.tools.build:gradle:2.2.3.
> Could not get resource 'https://maven.google.com/com/android/tools/build/gradle/2.2.3/gradle-2.2.3.pom'.
> Could not GET 'https://maven.google.com/com/android/tools/build/gradle/2.2.3/gradle-2.2.3.pom'.
> Connect to maven.google.com:443 [maven.google.com/203.208.40.95, maven.google.com/203.208.40.88, maven.google.com/203.208.40.87, maven.google.com/203.208.40.79] failed: Connection timed
out: connect
解决方案：
在platform/android目录下面新增一个文件
gradle.properties
文件里面设置网络代理：
systemProp.http.proxyHost=host
systemProp.http.proxyPort=port
systemProp.http.proxyUser=userid
systemProp.http.proxyPassword=password
systemProp.https.proxyHost=host
systemProp.https.proxyPort=port
systemProp.https.proxyUser=userid
systemProp.https.proxyPassword=password