To install Repo:

  1. Make sure you have a bin/ directory in your home directory and that it is included in your path: 

    $ mkdir ~/bin
    $ PATH=~/    bin:$PATH

  2. Download the Repo tool and ensure that it is executable: 

    $ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
    $ chmod a    +x ~/bin/repo

After installing Repo, set up your client to access the Android source repository:

  1. Create an empty directory to hold your working files. If you're using MacOS, this has to be on a case-sensitive filesystem. Give it any name you like: 

    $ mkdir WORKING_DIRECTORY
    $ cd WORKING_DIRECTORY

  2. Run repo init to bring down the latest version of Repo with all its most recent bug fixes. You must specify a URL for the manifest, which specifies where the various repositories included in the Android source will be placed within your working directory. 

    $ repo init -u https://android.googlesource.com/platform/manifest

    To check out a branch other than "master", specify it with -b: 

    $ repo init -u https://android.googlesource.com/platform/manifest -b android-4.0.1_r1

$ repo syn

实际操作中，获得错误报告：fatal: Cannot get https://gerrit.googlesource.com/git-repo/clone.bundle，

这个地址和你看到的可能不同，但肯定是 ~/bin/repo 第5行或第6行REPO_URL 所表示的网址。

stockoverflow上有贴提及是代理环境变量造成的问题，想到前面尝试过设置 HTTP_PROXY，用下面的指令清除，HTTPS_PROXY 存在的话也要清除 HTTPS_PROXY。

unset HTTP_PROXY

unset HTTPS_PROXY

然后repo init成功。。。，

如果遇到报错：fatal: '../platform/abi/cpp.git' does not appear to be a git repository

在.repo目录下的manifest.xml里找到fetch属性，改成
fetch="git://Android.git.linaro.org/"

提示输入你的姓名 及 邮件地址，你想要使用Gerrit code-review 工具的话就要用你申请的 Google账户使用的邮件地址，没有的话去申请一个，不用花多少时间。

Your Name [XXXXXX]: XXXXXX

6. repo 信息下载后，用 “repo sync”命令将真正的Android代码同步到当前工作目录显示下载状态类似下面

如果repo 操作中遇到网络连接问题，可以通过修改hosts文件尝试解决。Windows在C:\WINDOWS\system32\drivers\etc目录下，Linux用户打开/etc/hosts文件，在文件的末尾添加下面2句：

74.125.31.82 www.googlesource.com.
74.125.31.82 android.googlesource.com