// 使用HttpClient发送请求、接收响应很简单，一般需要如下几步即可。
// 1. 创建HttpClient对象。
// 2. 创建请求方法的实例，并指定请求URL。如果需要发送GET请求，创建HttpGet对象；如果需要发送POST请求，创建HttpPost对象。
// 3. 如果需要发送请求参数，可调用HttpGet、HttpPost共同的setParams(HetpParams params)方法来添加请求参数；对于HttpPost对象而言，也可调用setEntity(HttpEntity entity)方法来设置请求参数。
// 4. 调用HttpClient对象的execute(HttpUriRequest request)发送请求，该方法返回一个HttpResponse。
// 5. 调用HttpResponse的getAllHeaders()、getHeaders(String name)等方法可获取服务器的响应头；调用HttpResponse的getEntity()方法可获取HttpEntity对象，该对象包装了服务器的响应内容。程序可通过该对象获取服务器的响应内容。
// 6. 释放连接。无论执行方法是否成功，都必须释放连接
//入口函数
public static void main(String[] args) throws Exception {
        //cookie存储类
        BasicCookieStore cookieStore = new BasicCookieStore();
        //创建一个httpclient，并设置默认cookie存储cookieStore
        CloseableHttpClient httpclient = HttpClients.custom()
                .setDefaultCookieStore(cookieStore)
                .build();
        try {
            //创建HttpGet对象,需要发送GET请求https://someportal/
            HttpGet httpget = new HttpGet("https://someportal/");
            //HttpClient对象的execute(HttpUriRequest request)发送请求
            CloseableHttpResponse response1 = httpclient.execute(httpget);
            //try开始，试图执行
            try {
                //获取服务器返回的HttpEntity对象
                HttpEntity entity = response1.getEntity();
                //打印返回信息，response.getStatusLine().getStatusCode()==200链接成功，==500失败。
                System.out.println("Login form get: " + response1.getStatusLine());
                //HttpEntity对象提供的静态帮助类,EntityUtils.consume关闭资源
                EntityUtils.consume(entity);
                //打印Initial set of cookies:
                System.out.println("Initial set of cookies:");
                //获取Cookies并循环，空的输出None，否则输出cookie
                List<Cookie> cookies = cookieStore.getCookies();
                if (cookies.isEmpty()) {
                    System.out.println("None");
                } else {
                    for (int i = 0; i < cookies.size(); i++) {
                        System.out.println("- " + cookies.get(i).toString());
                    }
                }
            } finally {
                //关闭
                response1.close();
            }
            //POST请求，并设置URI和参数
            HttpUriRequest login = RequestBuilder.post()
                    .setUri(new URI("https://someportal/"))
                    .addParameter("IDToken1", "username")
                    .addParameter("IDToken2", "password")
                    .build();
            //执行POST请求
            CloseableHttpResponse response2 = httpclient.execute(login);
            try {
                //获取实体对象
                HttpEntity entity = response2.getEntity();
                //打印服务器返回信息
                System.out.println("Login form get: " + response2.getStatusLine());
                //关闭流
                EntityUtils.consume(entity);
                //打印cookie
                System.out.println("Post logon cookies:");
                List<Cookie> cookies = cookieStore.getCookies();
                if (cookies.isEmpty()) {
                    System.out.println("None");
                } else {
                    for (int i = 0; i < cookies.size(); i++) {
                        System.out.println("- " + cookies.get(i).toString());
                    }
                }
            } finally {
                response2.close();
            }
        } finally {
            //关闭httpclient
            httpclient.close();
        }
    }