一、Action（play.api.mvc.Action）
大多数的应用的请求都是由action进行处理，并生成一个结果给客户端，Action有多种创建方式：
1.
Action {Ok("Hello world")}
2.
Action { request =>Ok("Got request [" + request + "]")}
3.
Action { implicit request =>Ok("Got request [" + request + "]")}
4.
def action = Action { implicit request =>
anotherMethod("Some para value")
Ok("Got request [" + request + "]")
}
def anotherMethod(p: String)(implicit request: Request[_]) = {
// do something that needs access to the request
}5.
Action(parse.json) { implicit request =>Ok("Got request [" + request + "]")}
6.空的响应
def index(name:String) = TODO
二、 controller
controller通常是生成Action值的对象，通常把它定义为一个类而不是一个对象，例如：
package controllers import javax.inject.Inject import play.api.mvc._ class Application @Inject()(cc: ControllerComponents)extends AbstractController(cc) { def index = Action { Ok("It works!") } }
三、Result（play.api.mvc.Result）
1.带header和body的http结果
import play.api.http.HttpEntity def index = Action { Result( header = ResponseHeader(200, Map.empty), body = HttpEntity.Strict(ByteString("Hello world!"), Some("text/plain")) ) }
其他的一些结果
val ok = Ok("Hello world!")
val notFound = NotFound
val pageNotFound = NotFound(<h1>Page not found</h1>)
val badRequest = BadRequest(views.html.form(formWithErrors))
val oops = InternalServerError("Oops")
val anyStatus = Status(488)("Strange response type")
2.重定向到一个新的URL
def index = Action {Redirect("/user/home", MOVED_PERMANENTLY)}
四、Routes（conf/routes）
主要包含http请求方式（(GET, PATCH, POST, PUT, DELETE, HEAD）和请求地址
1.动态请求地址
GET /clients/:id controllers.Clients.show(id: Long)
包含多层结构的地址
GET /files/*name controllers.Application.download(name)
/files/images/logo.png中*name代表的是 images/logo.png
带正则表达式的地址
GET /items/$id<[0-9]+> controllers.Items.show(id: Long)
2.函数参数
GET /:page controllers.Application.show(page)
GET / controllers.Application.show(page)
第二个函数的参数，是请求到的内容
例子：
def show(id: Long) = Action { Client.findById(id).map { client => Ok(views.html.Clients.display(client)) }.getOrElse(NotFound) }
GET /clients controllers.Clients.list(page: Int ?= 1)
函数的参数带默认值
GET /api/list-all controllers.Api.list(version: Option[String])
可选的参数
3.反向路由
package controllers import javax.inject.Inject import play.api._ import play.api.mvc._ class Application @Inject()(cc:ControllerComponents) extends AbstractController(cc) { def hello(name: String) = Action { Ok("Hello " + name + "!") } } GET /hello/:name controllers.Application.hello(name) def helloBob = Action {Redirect(routes.Application.hello("Bob"))}
4.相对路由
package controllers import javax.inject._ import play.api.mvc._ @Singleton class Relative @Inject()(cc: ControllerComponents) extends AbstractController(cc) { def helloview() = Action { implicit request => Ok(views.html.hello("Bob")) } def hello(name: String) = Action { Ok(s"Hello $name!") } } GET /foo/bar/hello controllers.Relative.helloview GET /hello/:name controllers.Relative.hello(name) @(name: String)(implicit request: RequestHeader) <h1>Hello @name</h1> <a href="@routes.Relative.hello(name)">Absolute Link</a> <a href="@routes.Relative.hello(name).relative">Relative Link</a> <!DOCTYPE html> <html lang="en"> <head> <title>Bob</title> </head> <body> <a href="/hello/Bob">Absolute Link</a> <a href="../../hello/Bob">Relative Link</a> </body> </html>
5.一些默认的
# Redirects to https://www.playframework.com/ with 303 See Other GET /about controllers.Default.redirect(to = "https://www.playframework.com/") # Responds with 404 Not Found GET /orders controllers.Default.notFound # Responds with 500 Internal Server Error GET /clients controllers.Default.error # Responds with 501 Not Implemented GET /posts controllers.Default.todo