android最新源码（4.4.2_r1版本以上）下载
参考：http://source.android.com/source/downloading.html
红色字体表示多项选择中，我所做的选择
（我百度云盘地址：http://pan.baidu.com/s/1hqABuc8）
安装curl工具
$ sudo apt-get install curl
git工具的安装（按照如下方式安装最新版）
增加ppa
$ sudo apt-add-repository ppa:git-core/ppa
$ sudo apt-get update
$ sudo apt-get install git
git的版本号就是最新的
$ git --version
git version 1.8.5.2
错误：sudo apt-add-repository ppa:git-core/ppa时出现错误：gpg: requesting keyE1DF1F24from hkp server keyserver.ubuntu.com / gpgkeys: HTTP fetch error 7: couldn't connect to host
原因：keyserver.ubuntu.com使用非标准的11371端口，而一般公司的防火墙都屏蔽掉了该端口，而允许标准的80端口。
所以可以以如下方式强行使用80端口添加软件源：
$ sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 E1DF1F24
绿色部分是你要请求的Key.
repo工具的下载
google是这样告诉我们的：
$ curl http://commondatastorage.googleapis.com/git-repo-downloads/repo > ~/bin/repo
$ chmod a+x ~/bin/repo
但是好像是不能访问
解决方法：http://code.google.com/p/git-repo/downloads/detail?name=repo-1.12这个链接提供下载repo！
也可以通过下面命令得到：
$ curl http://git-repo.googlecode.com/files/repo-1.12 > ~/bin/repo
我是用在http后面加了个s下载的1.20，居然可以，没有其他版本出的错误
$ curl https://commondatastorage.googleapis.com/git-repo-downloads/repo > ./repo
具体的repo版本可以去查看http://code.google.com/p/git-repo/downloads页面上的信息，下载那个版本都行。
修改执行权限
$ chmod a+x repo
repo init创建仓库
初始化android 源代码，下载最新代码
$ ./repo init -u https://android.googlesource.com/platform/manifest
或者像这样取得某个分支如android-4.4.2_r1
$ ./repo init -u https://android.googlesource.com/platform/manifest -b android-4.4.2_r1
如果需要下载其他分支将android-4.4.2_r1改成其他分支名称就可以了。分支名称请在https://android.googlesource.com/platform/manifest/+refs里面查看branch
执行repo sync 进行同步
$ ./repo sync
使用repo sync同步下载代码时因为网络原因可能会经常断线，可以使用下面的脚本来做个脚本文件，让它中断后，又自动下载
创建脚本download.sh
#!/bin/bash
echo "=========start repo sync=============="
./repo sync
while [ $? == 1 ]; do
echo "======sync failed, re-sync again======"
sleep 3
./repo sync
done
chomd a+x download.sh让其可以运，然后终端输入./download.sh就可以开始下载了，用这一步代替官方文档里的repo sync。当连接不上终端时休息3毫秒然后再自动repo sync。
下载完成后，下一步就是编译了
补充：
对于我网盘下载的内容同步出源码的方法如下：
Usinga local mirror
When using several clients, especially in situationswhere bandwidth is scarce, it is better to create a local mirror of the entire servercontent, and to sync clients from that mirror (which requires no network access).The download for a full mirror is smaller than the download of two clients, whilecontaining more information.
These instructions assume that the mirror iscreated in /usr/local/aosp/mirror. The first step is to create and sync the mirroritself, which uses close to 13GB of network bandwidth and a similar amount of diskspace. Notice the --mirror flag, which can only be specified when creating a newclient:
$ mkdir -p /usr/local/aosp/mirror
$ cd /usr/local/aosp/mirror
$ repo init-u https://android.googlesource.com/mirror/manifest --mirror
$ repo sync
Once the mirror is synced, new clients can becreated from it. Note that it's important to specify an absolute path:
$ mkdir -p /usr/local/aosp/master
$ cd /usr/local/aosp/master
$ repo init-u /usr/local/aosp/mirror/platform/manifest.git
$ repo sync
Finally, to sync a client against the server,the mirror needs to be synced against the server, then the client against the mirror:
$ cd /usr/local/aosp/mirror
$ repo sync
$ cd /usr/local/aosp/master
$ repo sync
It's possible to store the mirror on a LAN serverand to access it over NFS, SSH or Git. It's also possible to store it on a removabledrive and to pass that drive around between users or between machines.