Martin Odersky created the Scala programming language in 2001 at EPFL. Some key events include the initial Java release in 2004, the Scala 2.0 release in 2006, and the founding of Typesafe by Odersky and Jonas Bonér in 2011 to support Scala. Scala can be used with build tools like Maven, Gradle, and SBT, and supports databases through libraries like Slick, ScalikeJDBC, and Squeryl. Frameworks like Play and Lift allow for web development in Scala. Testing libraries include ScalaCheck, Specs2, and Gatling.

1. SCALA ⽣生态圈
彭洪伟
!
@make_dream
!
hwpeng@thoughtworks.com

2. SCALA 知多少
2
▫︎A. 仅仅听过该名词，或更少
▫︎B. 了解过基本语法，有 Hello World 经验
▫︎C. 了解⽐比较多，有项⺫⽬目经验

3. SCALA 起源
3
▫︎出⽣生⽇日期：1958 - 09 - 05
▫︎国籍：德国
▫︎⺟母校：苏黎世联邦理⼯工学院
▫︎公司：Typesafe Inc.
▫︎成就：Java 泛型、Scala、MOOC
Martin Odersky

4. SCALA ⼤大事记
4
▫︎2001年，Scala 的设计在 EPFL 开始；
▫︎2004年初，Java 版发布；
▫︎2004年6⽉月，.NET 版发布；
▫︎2006年3⽉月，Scala 2.0 Java 版发布；
▫︎2011年5⽉月，Odersky和Jonas Bonér 创办 Typesafe；
▫︎2012年，官⽅方停⽌止维护 Scala .NET 版；
▫︎2014年，Scala 2.11.2 发布。

5. YOU DON’T KNOW
WHAT YOU DON’T
KNOW
As a developer, 最可怕的事情是什么？
5

6. AWESOME SCALA
6

7. BUILD TOOL - MAVEN
7
<repository>
<id>scala-tools.org</id>
<name>Scala-tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</repository>
<pluginRepository>
<id>scala-tools.org</id>
<name>Scala-tools Maven2 Repository</name>
<url>http://scala-tools.org/repo-releases</url>
</pluginRepository>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>2.11.1</version>
</dependency>
<plugin>
<groupId>org.scala-tools</groupId>
<artifactId>maven-scala-plugin</artifactId>
<executions>
<execution>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
</plugin>

8. BUILD TOOL - GRADLE
8
apply plugin: 'scala'
repositories {
mavenCentral()
}
dependencies {
compile 'org.scala-lang:scala-library:2.11.1'
}

9. BUILD TOOL - SBT
9
http://www.scala-sbt.org/
name := "hello world"
version := "0.0.1"
scalaVersion := "2.11.1"
resolvers ++= Seq (
Resolver.mavenLocal,
Resolver.sonatypeRepo ("releases"),
Resolver.typesafeRepo ("releases")
)
libraryDependencies ++=
Seq ("org.scala-lang" % "scala-compiler" % "2.11.1")
addSbtPlugin ("com.typesafe.play" % "sbt-plugin" % "2.3.1")

10. DB - SCALIKEJDBC
10
PostgreSQL、MySQL、H2、HSQLDB、Oracle、SQL Server… …
val orders: List[Order] = withSQL {
select
.from(Order as o)
.innerJoin(Product as p).on(o.productId, p.id)
.leftJoin(Account as a).on(o.accountId, a.id)
.where.eq(o.productId, 123)
.orderBy(o.id).desc
.limit(4)
.offset(0)
}.map(Order(o, p, a)).list.apply()
SELECT
o.*, p.*, a.*
FROM
orders o
INNER JOIN products p ON o.product_id = p.id
LEFT JOIN accounts a ON o.account_id = a.id
WHERE o.product_id = 123
ORDER BY o.id DESC
LIMIT 4
OFFSET 0

11. DB - SQUERYL
11
Postgres、Oracle、MySQL、H2、DB2、SQL Server、Derby
def songCountByArtistId: Query[GroupWithMeasures[Long, Long]] =
from(artists, songs)((a, s) =>
where(a.id === s.artistId)
groupBy (a.id)
compute (countDistinct(s.id))
)
SELECT
Artist1.id AS g0, count(DISTINCT Song2.id) AS c0
FROM
Artist Artist1, Song Song2
WHERE
(Artist1.id = Song2.artistId)
GROUP BY
Artist1.id

12. DB - SLICK
12
Derby、H2、HSQLDB、Access、MySQL、PostgreSQL、SQLite、
Oracle、DB2 、SQL Server
val q = coffees.filter(_.price > 20)
.sortBy(_.name.desc)
.drop(10)
.take(5)
SELECT
*
FROM
coffees
WHERE
price > 20
ORDER BY
name DESC
LIMIT 5
OFFSET 10

13. WEB - PLAY
13
route
GET /hello/:username HelloController.say(username: String)
controller
import play.api.mvc.{Action, Controller}
object HelloController extends Controller {
def say(username: String) = Action {
Ok(s"hello, $username")
}
}

14. WEB - *ATRA
14

15. WEB - LIFT
15
View First

16. TEST - SCALACHECK
16
Test
object StringSpec extends Properties("String") {
property("startWith") = forAll { (a: String, b: String) =>
(a + b).startsWith(a)
}
property("concatenate") = forAll { (a: String, b: String) =>
(a + b).length > a.length && (a + b).length > b.length
}
}
Result
+ String.startWith: OK, passed 100 tests.
! String.concat: Falsified after 0 passed tests.
> ARG_0: ""
> ARG_1: ""
!

17. TEST - SPEC2
17
Test
import org.specs2.mutable._
class HelloWorldSpec extends Specification {
"The 'Hello world' string" should {
"contain 11 characters" in {
"Hello world" must have size(11)
}
"start with 'Hello'" in {
"Hello world" must startWith("Hello")
}
"end with 'world'" in {
"Hello world" must endWith("world")
}
}
}

18. TEST - GATLING
18
class BasicSimulation extends Simulation {
val httpConf = http.baseURL("http://tax.myhpsnet.com:8800")
val scn = scenario("BasicSimulation")
.exec(http("get an invoice")
.get("/api/invoices/d361bb03-e762-3842-b6ae-a3062d1e5cf7"))
.pause(1)
setUp(scn.inject(atOnceUsers(100)).protocols(httpConf))
}

19. DISTRIBUTED SYSTEM
19

20. BIG DATA
20
100x faster than Hadoop MapReduce in memory
10x faster on disk.

21. REFERENCES
21
1. http://en.wikipedia.org/wiki/Martin_Odersky
2. http://en.wikipedia.org/wiki/Scala_(programming_language)
3. http://www.infoq.com/cn/articles/scala-technology
4. https://github.com/lauris/awesome-scala
5. http://agiledon.github.io/blog/2014/01/13/testing-styles-of-scalatest/
6. http://agiledon.github.io/blog/2014/07/20/scala-resource/

22. AD
Coursera上有⼀一⻔门免费的课程叫Functional
Programming Principles in Scala，由Scala
的作者Martin Odersky主讲。
22
https://www.coursera.org/course/progfun

23. Q&A