本頁假設您已安裝 sbt 1。
讓我們先從範例開始，而不是解釋 sbt 的運作方式或原因。
$ mkdir foo-build
$ cd foo-build
$ touch build.sbt
$ sbt
[info] Updated file /tmp/foo-build/project/build.properties: set sbt.version to 1.9.3
[info] welcome to sbt 1.9.3 (Eclipse Adoptium Java 17.0.8)
[info] Loading project definition from /tmp/foo-build/project
[info] loading settings for project foo-build from build.sbt ...
[info] Set current project to foo-build (in build file:/tmp/foo-build/)
[info] sbt server started at local:///Users/eed3si9n/.sbt/1.0/server/abc4fb6c89985a00fd95/sock
[info] started sbt server
sbt:foo-build>
要離開 sbt shell，請輸入 exit 或使用 Ctrl+D (Unix) 或 Ctrl+Z (Windows)。
sbt:foo-build> exit
按照慣例，我們將使用 sbt:...> 或 > 提示符號表示我們在 sbt 互動式 shell 中。
$ sbt
sbt:foo-build> compile
在 compile 命令（或任何其他命令）前面加上 ~，會導致在專案內的任何一個來源檔案被修改時，自動重新執行該命令。例如
sbt:foo-build> ~compile
[success] Total time: 0 s, completed 28 Jul 2023, 13:32:35
[info] 1. Monitoring source files for foo-build/compile...
[info] Press <enter> to interrupt or '?' for more options.
讓先前的命令繼續執行。從不同的 shell 或在您的檔案管理員中，於 foo-build 目錄中建立以下巢狀目錄：src/main/scala/example。然後，使用您喜愛的編輯器，在 example 目錄中建立 Hello.scala，如下所示
package example
object Hello {
def main(args: Array[String]): Unit = {
println("Hello")
}
}
這個新檔案應該會被正在執行的命令偵測到
[info] Build triggered by /tmp/foo-build/src/main/scala/example/Hello.scala. Running 'compile'.
[info] compiling 1 Scala source to /tmp/foo-build/target/scala-2.12/classes ...
[success] Total time: 0 s, completed 28 Jul 2023, 13:38:55
[info] 2. Monitoring source files for foo-build/compile...
[info] Press <enter> to interrupt or '?' for more options.
按下 Enter 鍵以退出 ~compile。
從 sbt shell 中，按兩次向上箭頭鍵，找到您在開頭執行的 compile 命令。
sbt:foo-build> compile
使用 help 命令來取得有關可用命令的基本說明。
sbt:foo-build> help
<command> (; <command>)* Runs the provided semicolon-separated commands.
about Displays basic information about sbt and the build.
tasks Lists the tasks defined for the current project.
settings Lists the settings defined for the current project.
reload (Re)loads the current project or changes to plugins project or returns from it.
new Creates a new sbt build.
new Creates a new sbt build.
projects Lists the names of available projects or temporarily adds/removes extra builds to the session.
....
顯示特定任務的描述
sbt:foo-build> help run
Runs a main class, passing along arguments provided on the command line.
sbt:foo-build> run
[info] running example.Hello
Hello
[success] Total time: 0 s, completed 28 Jul 2023, 13:40:31
sbt:foo-build> set ThisBuild / scalaVersion := "2.13.12"
[info] Defining ThisBuild / scalaVersion
[info] The new value will be used by Compile / bspBuildTarget, Compile / dependencyTreeCrossProjectId and 50 others.
[info] Run `last` for details.
[info] Reapplying settings...
[info] set current project to foo-build (in build file:/tmp/foo-build/)
檢查 scalaVersion 設定
sbt:foo-build> scalaVersion
[info] 2.13.12
我們可以使用 session save 儲存臨時設定。
sbt:foo-build> session save
[info] Reapplying settings...
[info] set current project to foo-build (in build file:/tmp/foo-build/)
[warn] build source files have changed
[warn] modified files:
[warn] /tmp/foo-build/build.sbt
[warn] Apply these changes by running `reload`.
[warn] Automatically reload the build when source changes are detected by setting `Global / onChangedBuildSource := ReloadOnSourceChanges`.
[warn] Disable this warning by setting `Global / onChangedBuildSource := IgnoreSourceChanges`.
build.sbt 檔案現在應該包含
ThisBuild / scalaVersion := "2.13.12"
使用編輯器，將 build.sbt 變更如下
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
lazy val hello = (project in file("."))
.settings(
name := "Hello"
)
使用 reload 命令重新載入建置。該命令會導致重新讀取 build.sbt 檔案，並套用其設定。
sbt:foo-build> reload
[info] welcome to sbt 1.9.3 (Eclipse Adoptium Java 17.0.8)
[info] loading project definition from /tmp/foo-build/project
[info] loading settings for project hello from build.sbt ...
[info] set current project to Hello (in build file:/tmp/foo-build/)
sbt:Hello>
請注意，提示符號現在已變更為 sbt:Hello>。
使用編輯器，將 build.sbt 變更如下
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
lazy val hello = project
.in(file("."))
.settings(
name := "Hello",
libraryDependencies += "org.scala-lang" %% "toolkit-test" % "0.1.7" % Test
)
使用 reload 命令反映 build.sbt 中的變更。
sbt:Hello> reload
sbt:Hello> test
sbt:Hello> ~testQuick
讓先前的命令繼續執行，使用編輯器建立名為 src/test/scala/example/HelloSuite.scala 的檔案
class HelloSuite extends munit.FunSuite {
test("Hello should start with H") {
assert("hello".startsWith("H"))
}
}
~testQuick 應該會偵測到變更
[info] 2. Monitoring source files for hello/testQuick...
[info] Press <enter> to interrupt or '?' for more options.
[info] Build triggered by /tmp/foo-build/src/test/scala/example/HelloSuite.scala. Running 'testQuick'.
[info] compiling 1 Scala source to /tmp/foo-build/target/scala-2.13/test-classes ...
HelloSuite:
==> X HelloSuite.Hello should start with H 0.004s munit.FailException: /tmp/foo-build/src/test/scala/example/HelloSuite.scala:4 assertion failed
3: test("Hello should start with H") {
4: assert("hello".startsWith("H"))
5: }
at munit.FunSuite.assert(FunSuite.scala:11)
at HelloSuite.$anonfun$new$1(HelloSuite.scala:4)
[error] Failed: Total 1, Failed 1, Errors 0, Passed 0
[error] Failed tests:
[error] HelloSuite
[error] (Test / testQuick) sbt.TestsFailedException: Tests unsuccessful
使用編輯器，將 src/test/scala/example/HelloSuite.scala 變更為
class HelloSuite extends munit.FunSuite {
test("Hello should start with H") {
assert("Hello".startsWith("H"))
}
}
確認測試通過，然後按下 Enter 鍵以退出持續測試。
使用編輯器，將 build.sbt 變更如下
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
lazy val hello = project
.in(file("."))
.settings(
name := "Hello",
libraryDependencies ++= Seq(
"org.scala-lang" %% "toolkit" % "0.1.7",
"org.scala-lang" %% "toolkit-test" % "0.1.7" % Test
)
)
使用 reload 命令反映 build.sbt 中的變更。
我們可以找出紐約的目前天氣。
sbt:Hello> console
[info] Starting scala interpreter...
Welcome to Scala 2.13.12 (OpenJDK 64-Bit Server VM, Java 17).
Type in expressions for evaluation. Or try :help.
scala> :paste
// Entering paste mode (ctrl-D to finish)
import sttp.client4.quick._
import sttp.client4.Response
val newYorkLatitude: Double = 40.7143
val newYorkLongitude: Double = -74.006
val response: Response[String] = quickRequest
.get(
uri"https://api.open-meteo.com/v1/forecast?latitude=$newYorkLatitude&longitude=$newYorkLongitude¤t_weather=true"
)
.send()
println(ujson.read(response.body).render(indent = 2))
// press Ctrl+D
// Exiting paste mode, now interpreting.
{
"latitude": 40.710335,
"longitude": -73.99307,
"generationtime_ms": 0.36704540252685547,
"utc_offset_seconds": 0,
"timezone": "GMT",
"timezone_abbreviation": "GMT",
"elevation": 51,
"current_weather": {
"temperature": 21.3,
"windspeed": 16.7,
"winddirection": 205,
"weathercode": 3,
"is_day": 1,
"time": "2023-08-04T10:00"
}
}
import sttp.client4.quick._
import sttp.client4.Response
val newYorkLatitude: Double = 40.7143
val newYorkLongitude: Double = -74.006
val response: sttp.client4.Response[String] = Response({"latitude":40.710335,"longitude":-73.99307,"generationtime_ms":0.36704540252685547,"utc_offset_seconds":0,"timezone":"GMT","timezone_abbreviation":"GMT","elevation":51.0,"current_weather":{"temperature":21.3,"windspeed":16.7,"winddirection":205.0,"weathercode":3,"is_day":1,"time":"2023-08-04T10:00"}},200,,List(:status: 200, content-encoding: deflate, content-type: application/json; charset=utf-8, date: Fri, 04 Aug 2023 10:09:11 GMT),List(),RequestMetadata(GET,https://api.open-meteo.com/v1/forecast?latitude=40.7143&longitude...
scala> :q // to quit
將 build.sbt 變更如下
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
lazy val hello = project
.in(file("."))
.settings(
name := "Hello",
libraryDependencies ++= Seq(
"org.scala-lang" %% "toolkit" % "0.1.7",
"org.scala-lang" %% "toolkit-test" % "0.1.7" % Test
)
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core"
)
使用 reload 命令反映 build.sbt 中的變更。
sbt:Hello> projects
[info] In file:/tmp/foo-build/
[info] * hello
[info] helloCore
sbt:Hello> helloCore/compile
將 build.sbt 變更如下
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.settings(
name := "Hello",
libraryDependencies ++= Seq(
"org.scala-lang" %% "toolkit" % "0.1.7",
toolkitTest % Test
)
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += toolkitTest % Test
)
設定 aggregate，使傳送至 hello 的命令也廣播至 helloCore
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.aggregate(helloCore)
.settings(
name := "Hello",
libraryDependencies ++= Seq(
"org.scala-lang" %% "toolkit" % "0.1.7",
toolkitTest % Test
)
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += toolkitTest % Test
)
在 reload 之後，~testQuick 現在會在兩個子專案上執行
sbt:Hello> ~testQuick
按下 Enter 鍵以退出持續測試。
使用 .dependsOn(...) 來新增對其他子專案的相依性。也讓我們將 toolkit 相依性移至 helloCore。
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.aggregate(helloCore)
.dependsOn(helloCore)
.settings(
name := "Hello",
libraryDependencies += toolkitTest % Test
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += "org.scala-lang" %% "toolkit" % "0.1.7",
libraryDependencies += toolkitTest % Test
)
讓我們在 helloCore 中使用 toolkit 中的 uJson。
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.aggregate(helloCore)
.dependsOn(helloCore)
.settings(
name := "Hello",
libraryDependencies += toolkitTest % Test
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += "org.scala-lang" %% "toolkit" % "0.1.7",
libraryDependencies += toolkitTest % Test
)
在 reload 之後，新增 core/src/main/scala/example/core/Weather.scala
package example.core
import sttp.client4.quick._
import sttp.client4.Response
object Weather {
def temp() = {
val response: Response[String] = quickRequest
.get(
uri"https://api.open-meteo.com/v1/forecast?latitude=40.7143&longitude=-74.006¤t_weather=true"
)
.send()
val json = ujson.read(response.body)
json.obj("current_weather")("temperature").num
}
}
接下來，將 src/main/scala/example/Hello.scala 變更如下
package example
import example.core.Weather
object Hello {
def main(args: Array[String]): Unit = {
val temp = Weather.temp()
println(s"Hello! The current temperature in New York is $temp C.")
}
}
讓我們執行應用程式看看是否正常運作
sbt:Hello> run
[info] compiling 1 Scala source to /tmp/foo-build/core/target/scala-2.13/classes ...
[info] compiling 1 Scala source to /tmp/foo-build/target/scala-2.13/classes ...
[info] running example.Hello
Hello! The current temperature in New York is 22.7 C.
使用編輯器，建立 project/plugins.sbt
addSbtPlugin("com.github.sbt" % "sbt-native-packager" % "1.9.4")
接下來，將 build.sbt 變更如下以新增 JavaAppPackaging
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.aggregate(helloCore)
.dependsOn(helloCore)
.enablePlugins(JavaAppPackaging)
.settings(
name := "Hello",
libraryDependencies += toolkitTest % Test,
maintainer := "A Scala Dev!"
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += "org.scala-lang" %% "toolkit" % "0.1.7",
libraryDependencies += toolkitTest % Test
)
sbt:Hello> reload
...
sbt:Hello> dist
[info] Wrote /private/tmp/foo-build/target/scala-2.13/hello_2.13-0.1.0-SNAPSHOT.pom
[info] Main Scala API documentation to /tmp/foo-build/target/scala-2.13/api...
[info] Main Scala API documentation successful.
[info] Main Scala API documentation to /tmp/foo-build/core/target/scala-2.13/api...
[info] Wrote /tmp/foo-build/core/target/scala-2.13/hello-core_2.13-0.1.0-SNAPSHOT.pom
[info] Main Scala API documentation successful.
[success] All package validations passed
[info] Your package is ready in /tmp/foo-build/target/universal/hello-0.1.0-SNAPSHOT.zip
以下是如何執行已封裝的應用程式
$ /tmp/someother
$ cd /tmp/someother
$ unzip -o -d /tmp/someother /tmp/foo-build/target/universal/hello-0.1.0-SNAPSHOT.zip
$ ./hello-0.1.0-SNAPSHOT/bin/hello
Hello! The current temperature in New York is 22.7 C.
請注意，Docker 精靈必須正在執行才能使其運作。
sbt:Hello> Docker/publishLocal
....
[info] Built image hello with tags [0.1.0-SNAPSHOT]
以下是如何執行 Docker 化的應用程式
$ docker run hello:0.1.0-SNAPSHOT
Hello! The current temperature in New York is 22.7 C.
將 build.sbt 變更如下
ThisBuild / version := "0.1.0"
ThisBuild / scalaVersion := "2.13.12"
ThisBuild / organization := "com.example"
val toolkitTest = "org.scala-lang" %% "toolkit-test" % "0.1.7"
lazy val hello = project
.in(file("."))
.aggregate(helloCore)
.dependsOn(helloCore)
.enablePlugins(JavaAppPackaging)
.settings(
name := "Hello",
libraryDependencies += toolkitTest % Test,
maintainer := "A Scala Dev!"
)
lazy val helloCore = project
.in(file("core"))
.settings(
name := "Hello Core",
libraryDependencies += "org.scala-lang" %% "toolkit" % "0.1.7",
libraryDependencies += toolkitTest % Test
)
sbt:Hello> ++3.3.1!
[info] Forcing Scala version to 3.3.1 on all projects.
[info] Reapplying settings...
[info] Set current project to Hello (in build file:/tmp/foo-build/)
檢查 scalaVersion 設定
sbt:Hello> scalaVersion
[info] helloCore / scalaVersion
[info] 3.3.1
[info] scalaVersion
[info] 3.3.1
此設定會在 reload 之後消失。
若要深入了解 dist，請嘗試 help 和 inspect。
sbt:Hello> help dist
Creates the distribution packages.
sbt:Hello> inspect dist
若要遞迴呼叫相依任務上的檢查，請使用 inspect tree。
sbt:Hello> inspect tree dist
[info] dist = Task[java.io.File]
[info] +-Universal / dist = Task[java.io.File]
....
您也可以在批次模式下執行 sbt，直接從終端機傳遞 sbt 命令。
$ sbt clean "testOnly HelloSuite"
注意：在批次模式下執行每次都需要 JVM 啟動和 JIT，因此您的建置執行速度會慢很多。對於日常編碼，我們建議使用 sbt shell 或像是 ~testQuick 的持續測試。
您可以使用 sbt new 命令來快速設定簡單的「Hello world」建置。
$ sbt new scala/scala-seed.g8
....
A minimal Scala project.
name [My Something Project]: hello
Template applied in ./hello
當系統提示輸入專案名稱時，輸入 hello。
這將會在名為 hello 的目錄下建立一個新專案。
本頁面基於 William “Scala William” Narmontas 撰寫的 Essential sbt 教學。
