浅谈Slick（4）－ Slick301：我的Slick开发项目设置

  前面几篇介绍里尝试了一些Slick的功能和使用方式，看来基本可以满足用scala语言进行数据库操作编程的要求，而且有些代码可以通过函数式编程模式来实现。我想，如果把Slick当作数据库操作编程主要方式的话，可能需要先制定一套比较规范的模式来应付日常开发（也要考虑团队开发）、测试和维护。首先从项目结构来说，我发现由Intellij-Idea IDE界面直接产生的SBT项目结构已经比较理想了。在src/main/resources是scala项目获取配置文件的默认目录、我们可以按照需要在src/main/scala下增加代码子目录（package）及在src/main/test下摆放测试代码。配置文件application.conf、logback.xml是放在src/main/resources下的。application.conf是Slick的配置文件，logback.xml是跟踪器logback（log4j）的配置文件。Slick把jdbc api集成到scala编程语言里，能够支持多种数据库。也就是说Slick提供了多种数据库的驱动api。Slick支持在配置文件application.conf里配置数据库功能模式，这样我们就可以在正式部署软件时才通过修订application.conf里的配置来决定具体的数据库种类和参数。当然前提是我们的程序代码不能依赖任何特别的数据库api。我们从表结构设定开始，先看看上篇Slick101里的例子：

package com.datatech.learn.slick101  2 import slick.driver.H2Driver.api._  3 object slick101 {  4 
/* ----- schema */
  //表字段对应模版
  case class AlbumModel (id: Long  8  ,title: String  9  ,year: Option[Int] 10  ,artist: String 11  ) 12   //表结构: 定义字段类型, * 代表结果集字段
  class AlbumTable(tag: Tag) extends Table[AlbumModel](tag, "ALBUMS") { 14     def id = column[Long]("ID",O.AutoInc,O.PrimaryKey) 15     def title = column[String]("TITLE") 16     def year = column[Option[Int]]("YEAR") 17     def artist = column[String]("ARTIST",O.Default("Unknown")) 18     def * = (id,title,year,artist) <> (AlbumModel.tupled, AlbumModel.unapply) 19  } 20   //库表实例
  val albums = TableQuery[AlbumTable]

我们可以看到这段代码依赖了slick.driver.H2Driver.api，是专门针对H2 Database的了。我们可以用依赖注入（dependency injection, IOC）来解决这个依赖问题。先试试用最传统的依赖注入方式：传入参数来注入这个数据库驱动依赖，把代码放在src/main/scala/model/TableDefs.scala里：

package com.bayakala.learn.slick301.model  2 import slick.driver.JdbcProfile  3 class TableDefs(val dbDriver: JdbcProfile) {  4  import dbDriver.api._  5   case class Supplier(id: Long  6  , name: String  7  , contact: Option[String]  8  , website: Option[String])  9   final class Suppliers(tag: Tag) extends Table[Supplier](tag,"SUPPLERS") { 10     def id = column[Long]("ID",O.AutoInc,O.PrimaryKey) 11     def name = column[String]("NAME") 12     def contact = column[Option[String]]("CONTACT") 13     def website = column[Option[String]]("WEBSITE") 14     def * = (id, name, contact, website) <> (Supplier.tupled,Supplier.unapply) 15     def nidx = index("NM_IDX",name,unique = true) 16  } 17   val suppliers = TableQuery[Suppliers] 18 
  case class Coffee(id: Long 20  ,name: String 21  ,supid: Long 22  ,price: Double 23  ,sales: Int) 24   final class Coffees(tag: Tag) extends Table[Coffee](tag, "COFFEES") { 25     def id = column[Long]("ID",O.AutoInc,O.PrimaryKey) 26     def name = column[String]("NAME") 27     def supid = column[Long]("SUPID") 28     def price = column[Double]("PRICE",O.Default(0.0)) 29     def sales = column[Int]("SALES",O.Default(0)) 30     def * = (id,name,supid,price,sales) <> (Coffee.tupled, Coffee.unapply) 31     def fk_sup = foreignKey("FK_SUP",supid,suppliers)(_.id,onDelete = ForeignKeyAction.Restrict,onUpdate = ForeignKeyAction.Cascade) 32     def supidx = index("SUP_IDX",supid,unique = false) 33     def nidx = index("NM_IDX",name,unique = true) 34  } 35   val coffees = TableQuery[Coffees] 36 
}

注意我们是把JdbcProfile作为参数注入了class TableDefs里。如果TableDefs经常需要作为其它类的父类继承的话，设计成trait能更加灵活的进行类型混合（type mixing）。这样的需求可以用cake pattern方式进行依赖注入。我们在需要src/main/scala/config/AppConfig.scala里定义依赖界面trait DBConfig：

package com.bayakala.learn.slick301.config 2 import slick.driver.JdbcProfile 3 trait DBConfig { 4  val jdbcDriver: JdbcProfile 5  import jdbcDriver.api._ 6  val db: Database 7 }

后面我们可以通过实现多种DBConfig实例方式来构建开发、测试、部署等数据库环境。为了方便示范，我们设计几个基本的Query Action，放在src/main/scala/access/DAOs.scala里，用cake pattern注入依赖DBConfig：

package com.bayakala.learn.slick301.access  2 import com.bayakala.learn.slick301.config  3 import com.bayakala.learn.slick301.config.DBConfig  4 import com.bayakala.learn.slick301.model.TableDefs  5 trait DAOs { dbconf: DBConfig =>
 import jdbcDriver.api._  7   //注入依赖
  val tables = new TableDefs(dbconf.jdbcDriver)  9  import tables._ 10   //suppliers queries
  val createSupplierTable = suppliers.schema.create 12   val allSuppliers = suppliers.result 13  def insertSupplier(id:Long,name:String,address:Option[String],website:Option[String]) 14   = suppliers += Supplier(id,name,address,website) 15   def insertSupbyName(n: String) = suppliers.map(_.name) += n 16   //coffees queries
  val createCoffeeTable = coffees.schema.create 18   val allCoffees = coffees.result 19   def insertCoffee(c: (Long,String,Long,Double,Int)) =
    coffees += Coffee(id=c._1, name=c._2,supid=c._3,price=c._4,sales=c._5) 21 
}

dbconf: DBConfig => 的意思是在进行DAOs的实例化时必须混入（mixing）DBConfig类。

以上两个代码文件TableDefs.scala和DAOs.scala在注入依赖后都能够顺利通过编译了。

我们在src/main/scala/main/Main.scala里测试运算DAOs里的query action：

package com.bayakala.learn.slick301.main  2 import com.bayakala.learn.slick301.config.DBConfig  3 import com.bayakala.learn.slick301.access.DAOs  4 
import scala.concurrent.{Await, Future}  6 import scala.util.{Failure, Success}  7 import scala.concurrent.duration._  8 import scala.concurrent.ExecutionContext.Implicits.global
import slick.backend.DatabaseConfig 10 import slick.driver.{H2Driver, JdbcProfile} 11 object Main { 12  
  object Actions extends DAOs with DBConfig { 14     override lazy val jdbcDriver: JdbcProfile = H2Driver 15     val dbConf: DatabaseConfig[H2Driver] = DatabaseConfig.forConfig("h2") 16     override val db = dbConf.db 17  } 18  import Actions._ 19   
  def main(args: Array[String]) = { 21     val res = db.run(createSupplierTable).andThen { 22       case Success(_) => println("supplier table created") 23       case Failure(_) => println("unable to create supplier table") 24  } 25     Await.ready(res, 3 seconds) 26 
    val res2 = db.run(insertSupbyName("Acme Coffee Co.")) 28     Await.ready(res2, 3 seconds) 29 
    Await.ready(db.run(allSuppliers), 10 seconds).foreach(println) 31 
    val res10 = db.run(createCoffeeTable).andThen { 33       case Success(_) => println("coffee table created") 34       case Failure(_) => println("unable to create coffee table") 35  } 36     Await.ready(res10, 3 seconds) 37 
    val res11 = db.run(insertCoffee((101,"Columbia",1,158.0,0))) 39     Await.ready(res11, 3 seconds) 40 
    Await.ready(db.run(allCoffees), 10 seconds).foreach(println) 42 
 } 44 
}

Actions是DAOs的实例。我们看到必须把DBConfig混入（mixin）。但是我们构建的数据库又变成了专门针对H2的api了，这样的话每次变动数据库对象我们就必须重新编译Main.scala，不符合上面我们提到的要求。我们可以把目标数据库放到application.conf里，然后在Main.scala里用typesafe-config实时根据application.conf里的设置确定数据库参数。src/main/resources/application.conf内容如下：

app = {  2   dbconfig = h2  3 }  4 
h2 {  6   driver = "slick.driver.H2Driver$"
 db {  8     url = "jdbc:h2:~/slickdemo;mv_store=false"
    driver = "org.h2.Driver"
    connectionPool = HikariCP 11     numThreads = 10
    maxConnections = 12
    minConnections = 4
    keepAliveConnection = true
 } 16 } 17 
h2mem = { 19   url = "jdbc:h2:mem:slickdemo"
  driver = org.h2.Driver 21   connectionPool = disabled 22   keepAliveConnection = true
} 24 
mysql { 26   driver = "slick.driver.MySQLDriver$"
 db { 28     url = "jdbc:mysql://localhost/slickdemo"
    driver = com.mysql.jdbc.Driver 30     keepAliveConnection = true
    user="root"
    password="123"
    numThreads=10
    maxConnections = 12
    minConnections = 4
 } 37 } 38 
mysqldb = { 40   dataSourceClass = "com.mysql.jdbc.jdbc2.optional.MysqlDataSource"
 properties { 42     user = "root"
    password = "123"
    databaseName = "slickdemo"
    serverName = "localhost"
 } 47   numThreads = 10
  maxConnections = 12
  minConnections = 4
} 51 
postgres { 53   driver = "slick.driver.PostgresDriver$"
 db { 55     url = "jdbc:postgresql://127.0.0.1/slickdemo"
    driver = "org.postgresql.Driver"
    connectionPool = HikariCP 58     user = "slick"
    password = "123"
    numThreads = 10
    maxConnections = 12
    minConnections = 4
 } 64 } 65 
postgressdb = { 67   dataSourceClass = "org.postgresql.ds.PGSimpleDataSource"
  properties = { 69     databaseName = "slickdemo"
    user = "slick"
    password = "123"
 } 73   connectionPool = HikariCP 74   numThreads = 10
  maxConnections = 12
  minConnections = 4
} 78 
mssql { 80   driver = "com.typesafe.slick.driver.ms.SQLServerDriver$"
 db { 82     url = "jdbc:sqlserver://host:port"
    driver = com.microsoft.sqlserver.jdbc.SQLServerDriver 84     connectionTimeout = 30 second 85     connectionPool = HikariCP 86     user = "slick"
    password = "123"
    numThreads = 10
    maxConnections = 12
    minConnections = 4
    keepAliveConnection = true
 } 93 } 94 
tsql { 96   driver = "slick.driver.H2Driver$"
  db = ${h2mem} 98 }

现在application.conf里除了数据库配置外又加了个app配置。我们在Main.scala里实例化DAOs时可以用typesafe-config读取app.dbconfig值后设定jdbcDriver和db：

  object Actions extends DAOs with DBConfig {  2  import slick.util.ClassLoaderUtil  3  import scala.util.control.NonFatal  4  import com.typesafe.config.ConfigFactory  5 
    def getDbConfig: String =
        ConfigFactory.load().getString("app.dbconfig")  8 
    def getDbDriver(path: String): JdbcProfile = { 10       val config = ConfigFactory.load() 11       val n = config.getString((if (path.isEmpty) "" else path + ".") + "driver") 12       val untypedP = try { 13         if (n.endsWith("$")) ClassLoaderUtil.defaultClassLoader.loadClass(n).getField("MODULE$").get(null) 14         else ClassLoaderUtil.defaultClassLoader.loadClass(n).newInstance() 15       } catch { 16         case NonFatal(ex) =>
          throw new SlickException(s"""Error getting instance of Slick driver "$n"""", ex) 18  } 19  untypedP.asInstanceOf[JdbcProfile] 20  } 21     
    override lazy val jdbcDriver: JdbcProfile = getDbDriver(getDbConfig) 23     val dbConf: DatabaseConfig[JdbcProfile] = DatabaseConfig.forConfig(getDbConfig) 24     override val db = dbConf.db 25   }

现在我们只需要改变application.conf里的app.dbconfig就可以转换目标数据库参数了。实际上，除了数据库配置，我们还可以在application.conf里进行其它类型的配置。然后用typesafe-config实时读取。如果不想在application.conf进行数据库之外的配置，可以把其它配置放在任何文件里，然后用ConfigFactory.load(path)来读取。

另外，在软件开发过程中跟踪除错也是很重要的。我们可以用logback来跟踪Slick、HikariCP等库的运行状态。logback配置在src/main/resources/logback.xml：

<?xml version="1.0" encoding="UTF-8"?>

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="application" level="DEBUG"/>
    <logger name="com.zaxxer.hikari" level="DEBUG"/>
    <logger name="slick" level="DEBUG"/>

    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
    </root>
</configuration>

DEBUG值可以显示最详细的状态信息。

好了，我把这次示范代码提供在下面：

build.sbt：

name := "learn-slick301"

version := "1.0"

scalaVersion := "2.11.8"

libraryDependencies ++= Seq(  8   "com.typesafe.slick" %% "slick" % "3.1.1",  9   "com.h2database" % "h2" % "1.4.191", 10   "com.typesafe.slick" %% "slick-hikaricp" % "3.1.1", 11   "ch.qos.logback" % "logback-classic" % "1.1.7", 12   "org.typelevel" %% "cats" % "0.7.2"

)

src/main/resources/

application.conf:

app = {  2   dbconfig = h2  3 }  4 
h2 {  6   driver = "slick.driver.H2Driver$"
 db {  8     url = "jdbc:h2:~/slickdemo;mv_store=false"
    driver = "org.h2.Driver"
    connectionPool = HikariCP 11     numThreads = 10
    maxConnections = 12
    minConnections = 4
    keepAliveConnection = true
 } 16 } 17 
h2mem = { 19   url = "jdbc:h2:mem:slickdemo"
  driver = org.h2.Driver 21   connectionPool = disabled 22   keepAliveConnection = true
} 24 
mysql { 26   driver = "slick.driver.MySQLDriver$"
 db { 28     url = "jdbc:mysql://localhost/slickdemo"
    driver = com.mysql.jdbc.Driver 30     keepAliveConnection = true
    user="root"
    password="123"
    numThreads=10
    maxConnections = 12
    minConnections = 4
 } 37 } 38 
mysqldb = { 40   dataSourceClass = "com.mysql.jdbc.jdbc2.optional.MysqlDataSource"
 properties { 42     user = "root"
    password = "123"
    databaseName = "slickdemo"
    serverName = "localhost"
 } 47   numThreads = 10
  maxConnections = 12
  minConnections = 4
} 51 
postgres { 53   driver = "slick.driver.PostgresDriver$"
 db { 55     url = "jdbc:postgresql://127.0.0.1/slickdemo"
    driver = "org.postgresql.Driver"
    connectionPool = HikariCP 58     user = "slick"
    password = "123"
    numThreads = 10
    maxConnections = 12
    minConnections = 4
 } 64 } 65 
postgressdb = { 67   dataSourceClass = "org.postgresql.ds.PGSimpleDataSource"
  properties = { 69     databaseName = "slickdemo"
    user = "slick"
    password = "123"
 } 73   connectionPool = HikariCP 74   numThreads = 10
  maxConnections = 12
  minConnections = 4
} 78 
mssql { 80   driver = "com.typesafe.slick.driver.ms.SQLServerDriver$"
 db { 82     url = "jdbc:sqlserver://host:port"
    driver = com.microsoft.sqlserver.jdbc.SQLServerDriver 84     connectionTimeout = 30 second 85     connectionPool = HikariCP 86     user = "slick"
    password = "123"
    numThreads = 10
    maxConnections = 12
    minConnections = 4
    keepAliveConnection = true
 } 93 } 94 
tsql { 96   driver = "slick.driver.H2Driver$"
  db = ${h2mem} 98 }

logback.xml:

<?xml version="1.0" encoding="UTF-8"?>

<configuration>
    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
        <encoder>
            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</pattern>
        </encoder>
    </appender>

    <logger name="application" level="DEBUG"/>
    <logger name="com.zaxxer.hikari" level="DEBUG"/>
    <logger name="slick" level="DEBUG"/>

    <root level="DEBUG">
        <appender-ref ref="STDOUT"/>
    </root>
</configuration>

src/main/scala/config/AppConfig.scala:

package com.bayakala.learn.slick301.config 2 import slick.driver.JdbcProfile 3 trait DBConfig { 4  val jdbcDriver: JdbcProfile 5  import jdbcDriver.api._ 6  val db: Database 7 }

src/main/scala/model/TableDefs.scala:

package com.bayakala.learn.slick301.model  2 import slick.driver.JdbcProfile  3 class TableDefs(val dbDriver: JdbcProfile) {  4  import dbDriver.api._  5   case class Supplier(id: Long  6  , name: String  7  , contact: Option[String]  8  , website: Option[String])  9   final class Suppliers(tag: Tag) extends Table[Supplier](tag,"SUPPLERS") { 10     def id = column[Long]("ID",O.AutoInc,O.PrimaryKey) 11     def name = column[String]("NAME") 12     def contact = column[Option[String]]("CONTACT") 13     def website = column[Option[String]]("WEBSITE") 14     def * = (id, name, contact, website) <> (Supplier.tupled,Supplier.unapply) 15     def nidx = index("NM_IDX",name,unique = true) 16  } 17   val suppliers = TableQuery[Suppliers] 18 
  case class Coffee(id: Long 20  ,name: String 21  ,supid: Long 22  ,price: Double 23  ,sales: Int) 24   final class Coffees(tag: Tag) extends Table[Coffee](tag, "COFFEES") { 25     def id = column[Long]("ID",O.AutoInc,O.PrimaryKey) 26     def name = column[String]("NAME") 27     def supid = column[Long]("SUPID") 28     def price = column[Double]("PRICE",O.Default(0.0)) 29     def sales = column[Int]("SALES",O.Default(0)) 30     def * = (id,name,supid,price,sales) <> (Coffee.tupled, Coffee.unapply) 31     def fk_sup = foreignKey("FK_SUP",supid,suppliers)(_.id,onDelete = ForeignKeyAction.Restrict,onUpdate = ForeignKeyAction.Cascade) 32     def supidx = index("SUP_IDX",supid,unique = false) 33     def nidx = index("NM_IDX",name,unique = true) 34  } 35   val coffees = TableQuery[Coffees] 36 
}

src/main/scala/access/DAOs.scala:

package com.bayakala.learn.slick301.access  2 import com.bayakala.learn.slick301.config  3 import com.bayakala.learn.slick301.config.DBConfig  4 import com.bayakala.learn.slick301.model.TableDefs  5 trait DAOs { dbconf: DBConfig =>
 import jdbcDriver.api._  7   //注入依赖
  val tables = new TableDefs(dbconf.jdbcDriver)  9  import tables._ 10   //suppliers queries
  val createSupplierTable = suppliers.schema.create 12   val allSuppliers = suppliers.result 13  def insertSupplier(id:Long,name:String,address:Option[String],website:Option[String]) 14   = suppliers += Supplier(id,name,address,website) 15   def insertSupbyName(n: String) = suppliers.map(_.name) += n 16   //coffees queries
  val createCoffeeTable = coffees.schema.create 18   val allCoffees = coffees.result 19   def insertCoffee(c: (Long,String,Long,Double,Int)) =
    coffees += Coffee(id=c._1, name=c._2,supid=c._3,price=c._4,sales=c._5) 21 
}

src/main/scala/main/Main.scala:

package com.bayakala.learn.slick301.main  2 import com.bayakala.learn.slick301.config.DBConfig  3 import com.bayakala.learn.slick301.access.DAOs  4 
import scala.concurrent.Await  6 import scala.util.{Failure, Success}  7 import scala.concurrent.duration._  8 import scala.concurrent.ExecutionContext.Implicits.global
import slick.backend.DatabaseConfig 10 import slick.driver.JdbcProfile 11 
object Main { 13 
  object Actions extends DAOs with DBConfig { 15  import slick.SlickException 16  import slick.util.ClassLoaderUtil 17  import scala.util.control.NonFatal 18  import com.typesafe.config.ConfigFactory 19 
    def getDbConfig: String =
        ConfigFactory.load().getString("app.dbconfig") 22 
    def getDbDriver(path: String): JdbcProfile = { 24       val config = ConfigFactory.load() 25       val n = config.getString((if (path.isEmpty) "" else path + ".") + "driver") 26       val untypedP = try { 27         if (n.endsWith("$")) ClassLoaderUtil.defaultClassLoader.loadClass(n).getField("MODULE$").get(null) 28         else ClassLoaderUtil.defaultClassLoader.loadClass(n).newInstance() 29       } catch { 30         case NonFatal(ex) =>
          throw new SlickException(s"""Error getting instance of Slick driver "$n"""", ex) 32  } 33  untypedP.asInstanceOf[JdbcProfile] 34  } 35 
    override lazy val jdbcDriver: JdbcProfile = getDbDriver(getDbConfig) 37     val dbConf: DatabaseConfig[JdbcProfile] = DatabaseConfig.forConfig(getDbConfig) 38     override val db = dbConf.db 39  } 40  import Actions._ 41 

  def main(args: Array[String]) = { 44 
    val res = db.run(createSupplierTable).andThen { 46       case Success(_) => println("supplier table created") 47       case Failure(_) => println("unable to create supplier table") 48  } 49     Await.ready(res, 3 seconds) 50 
    val res2 = db.run(insertSupbyName("Acme Coffee Co.")) 52     Await.ready(res2, 3 seconds) 53 
    Await.ready(db.run(allSuppliers), 10 seconds).foreach(println) 55 
    val res10 = db.run(createCoffeeTable).andThen { 57       case Success(_) => println("coffee table created") 58       case Failure(_) => println("unable to create coffee table") 59  } 60     Await.ready(res10, 3 seconds) 61 
    val res11 = db.run(insertCoffee((101,"Columbia",1,158.0,0))) 63     Await.ready(res11, 3 seconds) 64 
    Await.ready(db.run(allCoffees), 10 seconds).foreach(println) 66 
  }