Android 源码下载完成后，如何切换单个Git库的版本到历史任意版本？

1.通过git tag命令查看版本号

Administrator@USER-20140803NQ MINGW32 /c/androidandroidandroidandroid/Android7.0/base7.0/base (master)

$ git tag

afw-test-harness-1.5

afw-test-harness-2.1

android-1.6_r1

android-1.6_r1.1

android-1.6_r1.2

android-1.6_r1.3

android-1.6_r1.4

android-1.6_r1.5

android-1.6_r2

android-2.0.1_r1

android-2.0_r1

android-2.1_r1

android-2.1_r2

android-2.1_r2.1p

android-2.1_r2.1p2

android-2.1_r2.1s

android-2.2.1_r1

android-2.2.1_r2

android-2.2.2_r1

android-2.2.3_r1

android-2.2.3_r2

android-2.2.3_r2.1

android-2.2_r1

android-2.2_r1.1

android-2.2_r1.2

android-2.2_r1.3

android-2.3.1_r1

android-2.3.2_r1

android-2.3.3_r1

android-2.3.3_r1.1

android-2.3.4_r0.9

android-2.3.4_r1

android-2.3.5_r1

android-2.3.6_r0.9

android-2.3.6_r1

android-2.3.7_r1

android-2.3_r1

android-3.2.4_r1

android-4.0.1_r1

android-4.0.1_r1.1

android-4.0.1_r1.2

android-4.0.2_r1

android-4.0.3_r1

android-4.0.3_r1.1

android-4.0.4_r1

android-4.0.4_r1.1

android-4.0.4_r1.2

android-4.0.4_r2

android-4.0.4_r2.1

android-4.1.1_r1

android-4.1.1_r1.1

android-4.1.1_r2

android-4.1.1_r3

android-4.1.1_r4

android-4.1.1_r5

android-4.1.1_r6

android-4.1.1_r6.1

android-4.1.2_r1

android-4.1.2_r2

android-4.1.2_r2.1

android-4.2.1_r1

android-4.2.1_r1.1

android-4.2.1_r1.2

android-4.2.2_r1

android-4.2.2_r1.1

android-4.2.2_r1.2

android-4.2_r1

android-4.3.1_r1

android-4.3_r0.9

android-4.3_r0.9.1

android-4.3_r1

android-4.3_r1.1

android-4.3_r2

android-4.3_r2.1

android-4.3_r2.2

android-4.3_r2.3

android-4.3_r3

android-4.3_r3.1

android-4.4.1_r1

android-4.4.1_r1.0.1

android-4.4.2_r1

android-4.4.2_r1.0.1

android-4.4.2_r2

android-4.4.2_r2.0.1

android-4.4.3_r1

android-4.4.3_r1.0.1

android-4.4.3_r1.1

android-4.4.3_r1.1.0.1

android-4.4.4_r1

android-4.4.4_r1.0.1

android-4.4.4_r2

android-4.4.4_r2.0.1

android-4.4_r0.7

android-4.4_r0.8

android-4.4_r0.9

android-4.4_r1

android-4.4_r1.0.1

android-4.4_r1.1

android-4.4_r1.1.0.1

android-4.4_r1.2

android-4.4_r1.2.0.1

android-4.4w_r1

android-5.0.0_r1

android-5.0.0_r2

android-5.0.0_r3

android-5.0.0_r4

android-5.0.0_r5

android-5.0.0_r5.1

android-5.0.0_r6

android-5.0.0_r7

android-5.0.1_r1

android-5.0.2_r1

android-5.0.2_r3

android-5.1.0_r1

android-5.1.0_r3

android-5.1.0_r4

android-5.1.0_r5

android-5.1.1_r1

android-5.1.1_r10

android-5.1.1_r12

android-5.1.1_r13

android-5.1.1_r14

android-5.1.1_r15

android-5.1.1_r16

android-5.1.1_r17

android-5.1.1_r18

android-5.1.1_r19

android-5.1.1_r2

android-5.1.1_r20

android-5.1.1_r22

android-5.1.1_r23

android-5.1.1_r24

android-5.1.1_r25

android-5.1.1_r26

android-5.1.1_r28

android-5.1.1_r29

android-5.1.1_r3

android-5.1.1_r30

android-5.1.1_r33

android-5.1.1_r34

android-5.1.1_r35

android-5.1.1_r36

android-5.1.1_r37

android-5.1.1_r38

android-5.1.1_r4

android-5.1.1_r5

android-5.1.1_r6

android-5.1.1_r7

android-5.1.1_r8

android-5.1.1_r9

android-6.0.0_r1

android-6.0.0_r11

android-6.0.0_r12

android-6.0.0_r13

android-6.0.0_r2

android-6.0.0_r23

android-6.0.0_r24

android-6.0.0_r25

android-6.0.0_r26

android-6.0.0_r3

android-6.0.0_r4

android-6.0.0_r41

android-6.0.0_r5

android-6.0.0_r6

android-6.0.0_r7

android-6.0.1_r1

android-6.0.1_r10

android-6.0.1_r11

android-6.0.1_r12

android-6.0.1_r13

android-6.0.1_r16

android-6.0.1_r17

android-6.0.1_r18

android-6.0.1_r20

android-6.0.1_r21

android-6.0.1_r22

android-6.0.1_r24

android-6.0.1_r25

android-6.0.1_r26

android-6.0.1_r27

android-6.0.1_r28

android-6.0.1_r3

android-6.0.1_r30

android-6.0.1_r31

android-6.0.1_r32

android-6.0.1_r33

android-6.0.1_r4

android-6.0.1_r40

android-6.0.1_r41

android-6.0.1_r42

android-6.0.1_r43

android-6.0.1_r45

android-6.0.1_r46

android-6.0.1_r47

android-6.0.1_r48

android-6.0.1_r49

android-6.0.1_r5

android-6.0.1_r50

android-6.0.1_r51

android-6.0.1_r52

android-6.0.1_r53

android-6.0.1_r54

android-6.0.1_r55

android-6.0.1_r56

android-6.0.1_r57

android-6.0.1_r58

android-6.0.1_r59

android-6.0.1_r60

android-6.0.1_r61

android-6.0.1_r62

android-6.0.1_r63

android-6.0.1_r65

android-6.0.1_r66

android-6.0.1_r67

android-6.0.1_r68

android-6.0.1_r7

android-6.0.1_r8

android-6.0.1_r9

android-7.0.0_r1

android-7.0.0_r3

android-7.0.0_r4

android-7.0.0_r6

android-cts-2.2_r8

android-cts-2.3_r10

android-cts-2.3_r11

android-cts-2.3_r12

android-cts-4.0.3_r1

android-cts-4.0.3_r2

android-cts-4.0_r1

android-cts-4.1_r1

android-cts-4.1_r2

android-cts-4.1_r4

android-cts-4.2_r1

android-cts-4.2_r2

android-cts-4.4_r1

android-cts-4.4_r4

android-cts-5.0_r3

android-cts-5.0_r4

android-cts-5.0_r5

android-cts-5.0_r6

android-cts-5.0_r7

android-cts-5.0_r8

android-cts-5.0_r9

android-cts-5.1_r1

android-cts-5.1_r10

android-cts-5.1_r2

android-cts-5.1_r3

android-cts-5.1_r4

android-cts-5.1_r5

android-cts-5.1_r6

android-cts-5.1_r7

android-cts-5.1_r8

android-cts-5.1_r9

android-cts-6.0_r1

android-cts-6.0_r2

android-cts-6.0_r3

android-cts-6.0_r4

android-cts-6.0_r5

android-cts-6.0_r6

android-cts-6.0_r7

android-cts-6.0_r8

android-cts-6.0_r9

android-cts-7.0_r1

android-cts-verifier-4.0.3_r1

android-cts-verifier-4.0_r1

android-l-preview_r2

android-m-preview

android-m-preview-1

android-m-preview-2

android-n-preview-1

android-n-preview-2

android-n-preview-3

android-n-preview-4

android-n-preview-5

android-sdk-4.0.3-tools_r1

android-sdk-4.0.3_r1

android-sdk-4.4.2_r1

android-sdk-4.4.2_r1.0.1

android-sdk-adt_r16.0.1

android-sdk-adt_r20

android-sdk-support_r11

android-wear-5.0.0_r1

android-wear-5.1.0_r1

android-wear-5.1.1_r1

android-wear-n-preview-1

android-wear-n-preview-2

android-wear-n-preview-3

2.通过上面git tag查看到版本号，然后执行如下命令

git checkout  -b  本地分支  版本号

eg:假如需要切换到android-1.6_r1 这个版本，那么执行如下命令：

git  checkout   -b  android-1.6_r1  android-1.6_r1

注：此处 本地分支取的名称和版本号相同，这样取名有利于区别与其他本地分支，是一个好的取名方式。

如果执行的过程中，报出如下错误：

Administrator@USER-20140803NQ MINGW32 /c/androidandroidandroidandroid/Android7.0/base7.0/base (master)

$ git checkout   -b android-1.6_r1  android-1.6_r1
fatal: Unable to create 'C:/androidandroidandroidandroid/Android7.0/base7.0/base/.git/index.lock': File exists.

Another git process seems to be running in this repository, e.g.

an editor opened by 'git commit'. Please make sure all processes

are terminated then try again. If it still fails, a git process

may have crashed in this repository earlier:

remove the file manually to continue.

那么直接将.git目录下的index.lock文件删掉，然后重新执行上面的操作，见下：

Administrator@USER-20140803NQ MINGW32 /c/androidandroidandroidandroid/Android7.0/base7.0/base (master)

$ git checkout   -b android-1.6_r1  android-1.6_r1

Checking out files: 100% (34234/34234), done.

Switched to a new branch 'android-1.6_r1'

源码已经成功切换到android-1.6_r1版本了。