HTTPClient实现免登陆请求（带cookie请求）

背景：

使用httpClient请求某登录型网站，模拟一个操作，一般步骤一个httpclient模式登录-》httpClient模拟操作；

此时发现，每次操作都需要进行一次登录，极其浪费时间，是否可以通过某一方式进行一次登录多次操作，这里提供一种方式，带cookie登录。

登录获取cookie：

    public String loginModel(String username, String password) {
        String JSESSIONID = null;
        HttpPost httppost = new HttpPost(url);//httppost
        try {
            List<NameValuePair> para = new ArrayList<NameValuePair>();
            para.add(new BasicNameValuePair("password", password));
            para.add(new BasicNameValuePair("username", username));//构造表单
            httppost.setHeader(
                    "User-Agent",
                    "Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.118 Safari/537.36");
            httppost.setEntity(new UrlEncodedFormEntity(para, "utf-8"));//设置请求体
            BasicCookieStore cookieStore = new BasicCookieStore();//建立一个CookieStore
            CloseableHttpClient httpClient = HttpClients.custom().setDefaultCookieStore(cookieStore).build();//建立带cookie的httpClient
            int statuts_codes = httpClient.execute(httppost).getStatusLine().getStatusCode();//发送请求，发送成功后cookie将存在于cookieStore中
            if (statuts_codes == HttpStatus.SC_OK) {//请求成功
                List<Cookie> cookies = cookieStore.getCookies();//遍历获取需要的值
                for (int i = 0; i < cookies.size(); i++) {//获取JSESSIONID
                    if (cookies.get(i).getName().equals("id")) {
                        JSESSIONID = cookies.get(i).getValue();
                    }
                }
                cookieMap.put("JSESSIONID", JSESSIONID);
               
            } else {//请求失败
               
            }
        } catch (UnsupportedEncodingException ex) {
            
        } catch (IOException ex) {
            
        } finally {
            httppost.releaseConnection();//释放资源
        }
        return cookieMap.get("JSESSIONID");
    }

创建带有cookie的HttpClient

 public CloseableHttpClient getHttpClients(String username, String password) {
        BasicCookieStore cookieStore = new BasicCookieStore();
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        String JSESSIONID = loginModel(username, password);
        BasicClientCookie cookie = new BasicClientCookie("JSESSIONID", JSESSIONID);
        cookie.setVersion(0);
        String domain = Constant.HOOK_URL.substring(0, Constant.HOOK_URL.indexOf(":"));
        if (Constant.HOOK_URL.startsWith("http://")) {
            domain = Constant.HOOK_URL.substring(Constant.HOOK_URL.lastIndexOf("/") + 1, Constant.HOOK_URL.lastIndexOf(":"));
        }
        cookie.setDomain(domain);
        cookie.setPath(Constant.HOOK_FW);
        cookieStore.addCookie(cookie);
        //带有cookie的httpclient
        return httpClientBuilder.setDefaultCookieStore(cookieStore).build();
    }

使用：

public void useCookieHttpClient() {

        CloseableHttpClient httpClient = getHttpClients(user, pass);
        HttpPost httppost = new HttpPost(url2);
        List<NameValuePair> para = new ArrayList<>();//表单
        para.add("键", "值");
        httppost.setEntity(new UrlEncodedFormEntity(para, "utf-8"));
        httppost.setEntity(new UrlEncodedFormEntity(para, "utf-8"));
        CloseableHttpResponse res = httpClient.execute(httppost);
        int statuts_codes = res.getStatusLine().getStatusCode();
        if (statuts_codes == HttpStatus.SC_OK) {//请求成功
            String result = EntityUtils.toString(res.getEntity(), "utf-8");//返回值
        }

    }