基于JDK HttpServer的RESTEasy

原文: http://bluedash.net/spaces/%E5%9F%BA%E4%BA%8EJDK%20HttpServer%E7%9A%84RESTEasy

从RESTEasy 2.3开始，加入了一种新的无需Servlet容器的运行方式－通过使用JDK自带的轻量级HTTP Server进行加载。

HttpServer介绍

首先介绍一下JDK中自带的HttpServer，下面是一个例子：

01import com.sun.net.httpserver.Headers;

02import com.sun.net.httpserver.HttpExchange;

03import com.sun.net.httpserver.HttpHandler;

04import com.sun.net.httpserver.HttpServer;

05 

06import java.io.IOException;

07import java.io.OutputStream;

08import java.net.InetSocketAddress;

09import java.util.Iterator;

10import java.util.List;

11import java.util.Set;

12import java.util.concurrent.Executors;

13 

14public class HttpServerDemo {

15    public static void main(String[] args) throws IOException {

16        InetSocketAddress addr = new InetSocketAddress(8080);

17        HttpServer server = HttpServer.create(addr, 0);

18 

19        server.createContext("/", new MyHandler());

20        server.setExecutor(Executors.newCachedThreadPool());

21        server.start();

22        System.out.println("Server is listening on port 8080");

23    }

24}

25 

26class MyHandler implements HttpHandler {

27    public void handle(HttpExchange exchange) throwsIOException {

28        String requestMethod = exchange.getRequestMethod();

29        if (requestMethod.equalsIgnoreCase("GET")) {

30            Headers responseHeaders = exchange.getResponseHeaders();

31            responseHeaders.set("Content-Type","text/plain");

32            exchange.sendResponseHeaders(200, 0);

33 

34            OutputStream responseBody = exchange.getResponseBody();

35            Headers requestHeaders = exchange.getRequestHeaders();

36            Set<String> keySet = requestHeaders.keySet();

37            Iterator<String> iter = keySet.iterator();

38            while (iter.hasNext()) {

39                String key = iter.next();

40                List values = requestHeaders.get(key);

41                String s = key + " = " + values.toString() +"\n";

42                responseBody.write(s.getBytes());

43            }

44            responseBody.close();

45        }

46    }

47}

JDK自带的HttpServer是一个非常轻量级的Http服务端框架，但是它非常灵活，易于扩展，组成框架的核心类及框架为：

1com.sun.net.httpserver.HttpExchange;

2com.sun.net.httpserver.HttpHandler;

3com.sun.net.httpserver.HttpServer;

其中，HttpHandler框架是我们要实现的服务接口：通过处理HttpExchange中包含的Request，Response及各种HTTP协议信息，实现我们的处理逻辑。上面的例子中，在MyHandler中实现了服务器端的处理逻辑：将用户的请求信息打印出来。

最后，通过将HttpServer绑定至服务端口，进行启动：

1InetSocketAddress addr = new InetSocketAddress(8080);

2HttpServer server = HttpServer.create(addr, 0);

3server.start();

执行上面的例子，访问：

1http://localhost:8080

返回如下：

1Host = [localhost:8080]

2Accept-encoding = [gzip, deflate]

3Connection = [keep-alive]

4Accept-language = [en-us]

5User-agent = [Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_3) AppleWebKit/534.55.3 (KHTML, like Gecko) Version/5.1.5 Safari/534.55.3]

6Accept = [text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]

RESTEasy + HttpServer

从RESTEasy 2.3.3开始，添加了对JDK的HttpSever支持，使得RESTEasy容器可以脱离Servlet容器（比如Tomcat或JBoss），基于HttpSever启动。新的机制主要依赖于：

1org.jboss.resteasy.plugins.server.sun.http.HttpContextBuilder;

通过使用RESTEasy新提供的HttpContextBuilder，便可将RESTFul WebService注册进HttpServer。假设我们有resouce如下：

01@Path("/")

02public class SimpleResource

03{

04   @GET

05   @Path("basic")

06   @Produces("text/plain")

07   public String getBasic()

08   {

09      System.out.println("getBasic()");

10      return "basic";

11   }

12}

则结合HttpServer的具体调用方式如下：

1InetSocketAddress addr = new InetSocketAddress(8080);

2HttpServer httpServer = HttpServer.create(addr, 0);

3...

4contextBuilder = new HttpContextBuilder();

5contextBuilder.getDeployment().getActualResourceClasses().add(SimpleResource.class);

6contextBuilder.bind(httpServer);

7...

8httpServer.start();

RESTEasy的这一新模块位于RESTEasy源代码目录中的server-adapters/resteasy-jdk-http子项目：

1https://github.com/resteasy/Resteasy/tree/master/jaxrs/server-adapters/resteasy-jdk-http