AndroidStudio 更新失败，sdk更新失败。http://www.android-studio.org/ 下载AS安装包 跳转到Google，无法下载

解决问题

一、AndroidStudio    help——checkupdate    更新失败

二、sdk 更新失败

三、在http://www.android-studio.org/  网址下载AndroidStudio 安装包，点击网址下载。莫名其妙跳转到 Google 网址。并且打不开。无法下载。





造成这些问题的原因竟然是：

以前修改了host文件 增加Google host

203.208.46.146 dl.google.com
203.208.46.146 dl-ssl.google.com

现在删除 host 文件中的Google地址。就解决问题了。

host 文件在   C:\WINDOWS\system32\drivers\etc\host 文件

目前文件内容

# 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

补充：

android Studio里自己带proxy（代理） 。一般都能更新。

如果sdk还是更新不了。可以用镜像代理。      网址：http://www.androiddevtools.cn/

截图如下：