Android ICS 官方的下载地址是：http://source.android.com/source/downloading.html，用repo进行同步，具体的可以直接看链接，但是目前总会出现类似下面的错误：
1. Exception in thread Thread-3:
2. Traceback (most recent call last):
3. File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
4. self.run()
5. File "/usr/lib/python2.6/threading.py", line 484, in run
6. self.__target(*self.__args, **self.__kwargs)
7. File "/home/haili/android-4.0.4_r1.2/.repo/repo/subcmds/sync.py", line 200, in _FetchHelper
8. clone_bundle=not opt.no_clone_bundle)
9. File "/home/haili/android-4.0.4_r1.2/.repo/repo/project.py", line 978, in Sync_NetworkHalf
10. and self._ApplyCloneBundle(initial=is_new, quiet=quiet):
11. File "/home/haili/android-4.0.4_r1.2/.repo/repo/project.py", line 1519, in _ApplyCloneBundle
12. exist_dst = self._FetchBundle(bundle_url, bundle_tmp, bundle_dst, quiet)
13. File "/home/haili/android-4.0.4_r1.2/.repo/repo/project.py", line 1583, in _FetchBundle
14. raise DownloadError('%s: %s ' % (req.get_host(), str(e)))
15. DownloadError: android.googlesource.com: <urlopen error [Errno 110] Connection timed out>
16. ...
该错误看上去很奇怪，感觉像是python的问题，但是已经按照网上要求装了，最后报time out，qing yu建议换个时间段下下看，但是尝试过了很多次都无果，最后又看了下官方的文档介绍，发现有下面一句话：
Using authentication
By default, access to the Android source code is anonymous. To protect the servers against excessive usage, each IP address is associated with a quota.
When sharing an IP address with other users (e.g. when accessing the source repositories from beyond a NAT firewall), the quotas can trigger even for regular usage patterns (e.g. if many users sync new clients from the same IP address within a short period).
In that case, it is possible to use authenticated access, which then uses a separate quota for each user, regardless of the IP address.
The first step is to create a password from the password generator and to save it in ~/.netrc according to the instructions on that page.
The second step is to force authenticated access, by using the following manifest URI: https://android.googlesource.com/a/platform/manifest. Notice how the /a/ directory prefix triggers mandatory authentication. You can convert an existing client to use mandatory authentication with the following command:
$ repo init -u https://android.googlesource.com/a/platform/manifest
意思大体是：因为访问基本是匿名的，为了防止连接过多，对同一IP地址的连接数做了一定的限制。看来是用gmail帐号进行认证。
(*)因此，首先登录https://android.googlesource.com/new-password，使用gmail账户登录，然后点击网页上的“允许访问”，得到类似下面的信息：
[plain] view plaincopy
1. machine android.googlesource.com login git-<userName>.gmail.com password <password>
2. machine android-review.googlesource.com login git-<userName>.gmail.com password <password>
把上面那段信息（<userName>和<password>用自己得到的真实信息）追加到~/.netrc文件结尾；
(**)再下载地址的URL更改为https://android.googlesource.com/a/platform/manifest，（中间加上了“/a”）。
后面按照官方的步骤就可以拉代码了。
在此附上官方的方法：
1、
$ mkdir ~/bin
$ PATH=~/bin:$PATH
2、
$ curl https://dl-ssl.google.com/dl/googlesource/git-repo/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
3、
$ mkdir WORKING_DIRECTORY
$ cd WORKING_DIRECTORY
4、
$ repo init -u https://android.googlesource.com/platform/manifest -b android-4.0.4_r1.2 （注意：参考上面的(*)和(**)）
5、
$ repo sync