Android SDK下载和更新失败的解决方法！！！_android sdk&ndk tools下载失败:validation failed

开始搭建Android开发环境的时候，下载SDK总是会出现如下错误：

Failed to fetch URL http://dl-ssl.google.com/android/repository/addons_list-1.xml.

据说dl-ssl.google.com在大陆被强了，伟大的天朝真是不让人活了，解决方法就是修改C:\Windows\System32\drivers\etc\hosts文件。添加一行：

74.125.237.1       dl-ssl.google.com

这里需要注意的是hosts文件是只读的，我们没有权限修改，需要我们将hosts文件复制到桌面或者其他地方，然后修改，代码如下：

# Copyright (c) 1993-2009 Microsoft Corp.
#
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
#
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# space.
#
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a '#' symbol.
#
# For example:
#
#      102.54.94.97     rhino.acme.com          # source server
#       38.25.63.10     x.acme.com              # x client host
 
# localhost name resolution is handled within DNS itself.
#	127.0.0.1       localhost
#	::1             localhost
//亲，就是增加这一句哦
74.125.237.1       dl-ssl.google.com

然后保存，复制修改后的hosts文件到 C:\Windows\System32\drivers\etc 目录，替换文件就好！！！我们再次下载SDK的时候就会成功啦，如下图：

嘿嘿，大功告成啦！！！

PS：补充下，在mac或Linux中，hosts文件所在位置为/etc/hosts，可以使用sudo vim /etc/hosts来编辑。