com.sun.net.httpserver.HttpServer 挂起 [关闭]

有一个使用 HttpServer 的应用程序：

   public class HttpServer {
    private static final Logger log = Logger.getLogger(HttpServer.class);

    private com.sun.net.httpserver.HttpServer server = null;
    public void startHttpServer(int port) {

        try {
            server = com.sun.net.httpserver.HttpServer.create(new InetSocketAddress(port), 0);
        } catch (IOException e) {
            log.error(e.getStackTrace());
        }
        System.out.println("HTTP server started at " + port);
        server.createContext("/", new RootHandler());
        server.createContext("/limit_objects", new GetLimitHandler());
        server.createContext("/need_update_metadata", new PostUpdateMetadata());
        server.createContext("/update_limit_objects", new PostUpdateLimitHandler());
        server.setExecutor(Executors.newCachedThreadPool());
        server.start();
    }
}

class RootHandler implements HttpHandler {
    @Override
    public void handle(HttpExchange he) throws IOException {
        String response = "{\"Result\": \"I am working!\"}";
        he.sendResponseHeaders(200, response.length());
        OutputStream os = he.getResponseBody();
        os.write(response.getBytes());
        os.close();
    }
}

class GetLimitHandler implements HttpHandler {
    private static final Logger log = Logger.getLogger(GetLimitHandler.class);

    @Override
    public void handle(HttpExchange httpExchange) {
        String response = limits.toString();
        try {
            httpExchange.sendResponseHeaders(200, limits.toString().length());
            OutputStream outputStream = httpExchange.getResponseBody();
            outputStream.write(response.getBytes());
            outputStream.close();
        } catch (IOException e) {
            log.error(e.getStackTrace());
        }

    }
}

class PostUpdateMetadata implements HttpHandler {
    private static final Logger log = Logger.getLogger(PostUpdateMetadata.class);

    @Override
    public void handle(HttpExchange he) {

        String response = "{\"Result\": \"Metadata was update\"}";

        SettingTopicProperties settingTopicProperties = new SettingTopicProperties();
        settingTopicProperties.createZNode(needUpdateMetadata, "");

        try {
            he.sendResponseHeaders(200, response.length());
            OutputStream outputStream = he.getResponseBody();
            outputStream.write(response.getBytes());
            outputStream.close();
        } catch (IOException e) {
            log.error(e.getStackTrace());
        }
    }
}

class PostUpdateLimitHandler implements HttpHandler {
    private static final Logger log = Logger.getLogger(PostUpdateLimitHandler.class);
    @Override

    public void handle(HttpExchange he) {
        InputStreamReader inputStreamReader = null;
        try {
            inputStreamReader = new InputStreamReader(he.getRequestBody(), "utf-8");
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String query = bufferedReader.readLine();

            String response = "{\"Result\": \"Limit of objects was updated\"}";

            SettingTopicProperties settingTopicProperties = new SettingTopicProperties();
            settingTopicProperties.update(recordLimitProperties, query.getBytes());

            he.sendResponseHeaders(200, response.length());
            OutputStream os = he.getResponseBody();
            os.write(response.getBytes());
            os.close();
        } catch (IOException e) {
            log.error(e.getStackTrace());
        }
    }
}

对服务器的所有请求都正常处理。但是应用程序在停止时会冻结。如果不向 HttpServer 发送请求，则正常停止。可能是什么问题呢？