下载android代码过程中，提示以下错误：
error: Failed connect to android.googlesource.com:443;Connection refused while accessinghttps://android.googlesource.com/a/platform/frameworks/base/info/refs
fatal: HTTP request failed
error: Cannot fetch platform/tools/motodev
error: Cannot fetch platform/frameworks/base
error: Cannot fetch platform/prebuilts/sdk
error: Exited sync due to fetch errors
解决方法：编辑/etc/hosts文件
$ vim /etc/hosts
增加下面内容，保存（提前保存好）：
74.125.31.82 www.googlesource.com
74.125.31.82 android.googlesource.com
203.208.46.172 cache.pack.google.com
59.24.3.173 cache.pack.google.com
然后重新输入
$ repo sync