傳統下載方法：Android源碼下載流程
使用傳統方法下載，首次同步需要下載約 60GB 數據，過程中任何網絡故障都可能造成同步失敗，需要頻繁輸入repo sync，一點都不省心。
清華鏡像站提供了另外一種下載方法，每月更新的初始化包，直接下載一個tar包，直接解壓放出代碼即可。之後還可以使用repo sync同步最新代碼，和傳統方法並無差別。
一、下載aosp-latest.tar
下載初始化包
wget -c https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-latest.tar
下載trace顯示，從下午4點到晚上12點，下了8個鐘，才下完。不過還是很順利，沒有出現下載失敗的情況。
--2019-11-28 16:24:33-- https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Resolving mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)... 101.6.8.193, 2402:f000:1:408:8100::1
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 65436395520 (61G) [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 0%[ ] 353.45M 49.4KB/s in 7m 52s
2019-11-28 16:32:25 (767 KB/s) - Connection closed at byte 370622121. Retrying.
--2019-11-28 16:32:26-- (try: 2) https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 206 Partial Content
Length: 65436395520 (61G), 65065773399 (61G) remaining [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 2%[==> ] 1.65G 3.95MB/s in 11m 47s
2019-11-28 16:59:13 (1.89 MB/s) - Read error at byte 1773649187/65436395520 (Success). Retrying.
--2019-11-28 16:59:15-- (try: 3) https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 206 Partial Content
Length: 65436395520 (61G), 63662746333 (59G) remaining [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 39%[+++===========================================> ] 24.20G 2.05MB/s in 2h 30m
2019-11-28 19:29:45 (2.56 MB/s) - Connection closed at byte 25983204252. Retrying.
--2019-11-28 19:29:48-- (try: 4) https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 206 Partial Content
Length: 65436395520 (61G), 39453191268 (37G) remaining [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 42%[+++++++++++++++++++++++++++++++++++++++++++++++==> ] 26.11G 871KB/s in 23m 5s
2019-11-28 19:52:53 (1.41 MB/s) - Connection closed at byte 28031564308. Retrying.
--2019-11-28 19:52:57-- (try: 5) https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 206 Partial Content
Length: 65436395520 (61G), 37404831212 (35G) remaining [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 49%[++++++++++++++++++++++++++++++++++++++++++++++++++=======> ] 30.14G 1008KB/s in 40m 49s
2019-11-28 20:33:48 (1.69 MB/s) - Connection closed at byte 32366786700. Retrying.
--2019-11-28 20:33:53-- (try: 6) https://mirrors.tuna.tsinghua.edu.cn/aosp-monthly/aosp-20191101.tar
Connecting to mirrors.tuna.tsinghua.edu.cn (mirrors.tuna.tsinghua.edu.cn)|101.6.8.193|:443... connected.
HTTP request sent, awaiting response... 206 Partial Content
Length: 65436395520 (61G), 33069608820 (31G) remaining [application/octet-stream]
Saving to: ‘aosp-20191101.tar’
aosp-20191101.tar 100%[++++++++++++++++++++++++++++++++++++++++++++++++++++++++++============================================================>] 60.94G 3.95MB/s in 3h 40m
2019-11-29 00:13:58 (2.39 MB/s) - ‘aosp-20191101.tar’ saved [65436395520/65436395520]
二、解壓並同步代碼
解壓，解壓到aosp工程目錄，解壓時間根據系統性能決定。
tar xf aosp-latest.tar
解壓完成後進入aosp目錄，這時 ls 的話什麼也看不到，因爲只有一個隱藏的 .repo 目錄
cd aosp
同步代碼，正常同步一遍即可得到完整目錄
repo sync
或 repo sync -l 僅checkout代碼，也就是不需要聯網，直接本地同步出代碼
三、更新代碼
每次只需運行 repo sync 即可保持同步。
參考
