在Androidstudio中打开一个android项目（在这里我们以project方式打开），能够看到工程中其实有两个.gitignore文件。如下图所示：
这两个文件都需要配置。app目录下gitigonre文件内容为：/build。也就是我们需要忽略掉build文件夹下的内容。
另一个gitigonre文件内容如下所示：
# Built application files
*.apk
*.ap_
*.aab
# Files for the ART/Dalvik VM
*.dex
# Java class files
*.class
# Generated files
bin/
gen/
out/
# Gradle files
.gradle/
build/
# Local configuration file (sdk path, etc)
local.properties
# Proguard folder generated by Eclipse
proguard/
# Log Files
*.log
# Android Studio Navigation editor temp files
.navigation/
# Android Studio captures folder
captures/
# IntelliJ
*.iml
.idea/workspace.xml
.idea/tasks.xml
.idea/gradle.xml
.idea/assetWizardSettings.xml
.idea/dictionaries
.idea/libraries
.idea/caches
# Keystore files
# Uncomment the following line if you do not want to check your keystore files in.
#*.jks
# External native build folder generated in Android Studio 2.2 and later
.externalNativeBuild
# Google Services (e.g. APIs or Firebase)
google-services.json
# Freeline
freeline.py
freeline/
freeline_project_description.json
# fastlane
fastlane/report.xml
fastlane/Preview.html
fastlane/screenshots
fastlane/test_output
fastlane/readme.md
其中"#"表示注释，"*"表示通配符，可多个，"/"表示目录
