在 Scala 中引导 Web 服务器 [英] Bootstrapping a web server in Scala
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问题描述
使用 Python 可以实现以下功能:
The following is possible using Python:
$ apt-get install python
$ easy_install Flask
$ cat > hello.py
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
return "Hello World!"
if __name__ == "__main__":
app.run()
$ python hello.py
让网络服务器运行的 4 个命令和 7 行代码确实令人印象深刻.
4 commands and 7 lines of code to get a web server running is very impressive indeed.
Scala 的等价物是什么?
What's the Scala equivalent?
推荐答案
这里使用了 JDK6 内置的 HttpServer 类.随时提出改进建议，我是 Scala 的新手.
This uses the HttpServer class that is built-in in JDK6. Feel free to suggest improvements, I'm new to Scala.
package org.test.simplehttpserver
import java.net.InetSocketAddress
import com.sun.net.httpserver.{HttpExchange, HttpHandler, HttpServer}
import collection.mutable.HashMap
abstract class SimpleHttpServerBase(val socketAddress: String = "127.0.0.1",
val port: Int = 8080,
val backlog: Int = 0) extends HttpHandler {
private val address = new InetSocketAddress(socketAddress, port)
private val server = HttpServer.create(address, backlog)
server.createContext("/", this)
def redirect(url: String) =
<html>
<head>
<meta http-equiv="Refresh" content={"0," + url}/>
</head>
<body>
You are being redirected to:
<a href={url}>
{url}
</a>
</body>
</html>
def respond(exchange: HttpExchange, code: Int = 200, body: String = "") {
val bytes = body.getBytes
exchange.sendResponseHeaders(code, bytes.size)
exchange.getResponseBody.write(bytes)
exchange.getResponseBody.write("\r\n\r\n".getBytes)
exchange.getResponseBody.close()
exchange.close()
}
def start() = server.start()
def stop(delay: Int = 1) = server.stop(delay)
}
abstract class SimpleHttpServer extends SimpleHttpServerBase {
private val mappings = new HashMap[String, () => Any]
def get(path: String)(action: => Any) = mappings += path -> (() => action)
def handle(exchange: HttpExchange) = mappings.get(exchange.getRequestURI.getPath) match {
case None => respond(exchange, 404)
case Some(action) => try {
respond(exchange, 200, action().toString)
} catch {
case ex: Exception => respond(exchange, 500, ex.toString)
}
}
}
class HelloApp extends SimpleHttpServer {
var count = 0
get("/") {
"There's nothing here"
}
get("/hello") {
"Hello, world!"
}
get("/markup") {
<html>
<head>
<title>Test Title</title>
</head>
<body>
Test Body
</body>
</html>
}
def countPage = <html>
<head>
<title>Test Title</title>
</head>
<body>
Count:
{count}<a href="/increaseCount">++</a>
<a href="/decreaseCount">--</a>
<a href="/resetCount">Reset</a>
</body>
</html>
get("/count") {
countPage
}
get("/resetCount") {
count = 0
redirect("/count")
}
get("/increaseCount") {
count = count + 1
redirect("/count")
}
get("/decreaseCount") {
count = count - 1
redirect("/count")
}
get("/error") {
throw new RuntimeException("Bad bad error occurred")
}
}
object Main {
def main(args: Array[String]) {
val server = new HelloApp()
server.start()
}
}
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