JDK6中httpserver实例

前面说到HttpServer是JDK6提供的一个轻量的http server，位于

• com.sun.net.httpserver
• com.sun.net.httpserver.spi

主要的接口或类如下

Class/interface What does it do?

HttpServer	Listens on a particular port number and address for incoming Http requests
HttpsServer	Same as for HttpServer except for Https requests
HttpHandler	Programmer implements this. Handler is called to handle each incoming Http request
HttpExchange	Encapsulates all of the information about a Http request and the corresponding response
HttpContext	Represents one Http application on a HttpServer instance. It is identified by the URI path to the application, and has a HttpHandler associated

更多的详情见这里。下面来见一个简单的例子

1、创建一个HttpServer实例

InetSocketAddress addr = new InetSocketAddress(8080);
//创建一个httpserver实例，0表示开启服务
HttpServer server = HttpServer.create(addr, 0);
//HttpContext与servlet中的ServletContext类似
//这里指定了ContextPath（/get/user），以及相应的Handler(Servlet)
HttpContext context = server.createContext("/get/user", new ParameterHandler());
//这里指定了Filter
context.getFilters().add(new ParameterFilter());
server.setExecutor(Executors.newCachedThreadPool());
server.start();

 这样就创建了一个端口8080的http server当前对其中注册的Handler和Filter接下来需要说明

 

2、这里的ParameterHandler需要实现HttpHandler用来处理请求。这里实现一个简单用例：打印headers和将请求中的参数作为string返回

public class ParameterHandler implements HttpHandler {

    public void handle(HttpExchange exchange) throws IOException {

        String requestMethod = exchange.getRequestMethod();
        if (requestMethod.equalsIgnoreCase("GET")) {
            Headers responseHeaders = exchange.getResponseHeaders();
            responseHeaders.set("Content-Type", "text/plain");
            exchange.sendResponseHeaders(200, 0);

            OutputStream responseBody = exchange.getResponseBody();
            Headers requestHeaders = exchange.getRequestHeaders();
            Set<String> keySet = requestHeaders.keySet();
            Iterator<String> iter = keySet.iterator();
            //print headers info
            responseBody.write("headers: \n".getBytes());
            while (iter.hasNext()) {
                String key = iter.next();
                List<?> values = requestHeaders.get(key);
                String s = key + " = " + values.toString() + "\n";
                responseBody.write(s.getBytes());
            }

            //print parameters
            responseBody.write("parameters: \n".getBytes());
            @SuppressWarnings("unchecked")
            Map<String, String> params = (Map<String, String>) exchange.getAttribute("parameters");
            for (Map.Entry<String, String> entry : params.entrySet()) {
                responseBody.write((entry.getKey() + " = " + entry.getValue() + "\n").getBytes());
            }

            responseBody.close();
        }
    }

}

 

3、在上面的ParameterHandler中我们用到了

exchange.getAttribute("parameters");

 但是parameters并没有处理，这就需要在Filter中来实现。也是在HttpContext 中加入的Filter，需要继承Filter。这和Servlet规范中很类似吧

public class ParameterFilter extends Filter {

    @Override
    public String description() {
        return "description...";
    }

    @Override
    public void doFilter(HttpExchange exchange, Chain chain) throws IOException {
        URI uri = exchange.getRequestURI();
        String rawQuery = uri.getRawQuery();
        if (null != rawQuery) {
            Map<String, String> map = new HashMap<String, String>();
            String[] params = rawQuery.split("&");
            for (String param : params) {
                String[] paras = param.split("\\=");
                map.put(paras[0], paras[1]);
            }
            exchange.setAttribute("parameters", map);
        }
        chain.doFilter(exchange);
    }
}

 这里只是把请求(GET)中的参数做简单的处理并设置到HttpContext中。

 

4、到这一步这个例子也已差不多了，运行1中的代码即可在浏览器中访问，比如我们的访问及结果如下：

//RequestUrl
http://localhost:8080/get/user?name=robin&gender=male

headers: 
Host = [localhost:8080]
Accept-charset = [GBK,utf-8;q=0.7,*;q=0.3]
Accept-encoding = [gzip,deflate,sdch]
Connection = [keep-alive]
Accept-language = [zh-CN,zh;q=0.8]
User-agent = [Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.4 (KHTML, like Gecko) Chrome/22.0.1229.96 Safari/537.4]
Accept = [text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
parameters: 
name = robin
gender = male

 DONE!