HttpClient之實現POST方法

實現方法

使用HttpClient發送請求、接收響應很簡單，一般需要如下幾步即可。
1. 創建HttpClient對象。
2. 創建請求方法的實例：HttpGet對象或HttpPost，並指定請求URL。
3. 設置配置參數，通過RequestConfig可以配置連接超時時間、Socket超時時間等重要參數
4. 設置請求參數，HttpGet、HttpPost使用setParams(HttpParams params)添加請求參數；HttpPost還可用setEntity(HttpEntity entity)方法來添加請求參數。
5. 調用HttpClient.execute(HttpUriRequest request)發送請求，響應結果封裝於HttpResponse。
6. HttpResponse.getAllHeaders()、getHeaders(String name)方法可獲取響應頭；HttpResponse.getEntity()可獲取響應結果;HttpResponse.getStatusLine可獲取響應狀態碼
7. 將字節流轉換成字符串
8. 釋放http連接（重要）

POST方法重要部分說明

1. 通過costTime記錄請求響應具體時間，方便後續監控執行時間
2. 通過service字段記錄此方法調用方，通過記錄日誌可以統計調用方qps
3. 異常細化處理，該方法可捕捉ConnectTimeoutException、 SocketTimeoutException異常，正對此類異常可以專門監控統計（此類異常出現，要麼是網絡抖動，要麼是對方服務宕機，會導致嚴重後果，需要特殊處理）

代碼

    public static String doPost(String service,String url, Map<String, String> params,Map<String,String> headers,int timeout) {
        //通過service字段，打印日誌， 方便統計qps
        logger.info("begin http call service={},method={},url={}",service,"post",url);
        CloseableHttpClient httpclient = null;
        CloseableHttpResponse response = null;
        //記錄請求響應時間
        long costTime = 0;
        String result = null;
        try {
            long start = System.currentTimeMillis();
            //1、創建HttpClient
            httpclient = HttpClients.createDefault();
            //2、指定URL創建HttpPost
            HttpPost httpPost = new HttpPost(url);
            //3、設置配置：連接超時時間和Socket超時時間
            RequestConfig config = RequestConfig.custom().setConnectTimeout(timeout).setSocketTimeout(timeout).build();
            httpPost.setConfig(config);
            //4、設置請求參數
            List<NameValuePair> nvps = new ArrayList<>();
            if(params != null && params.keySet().size() > 0) {
                for(Map.Entry<String, String> entry : params.entrySet()) {
                    nvps.add(new BasicNameValuePair(entry.getKey(), entry.getValue()));
                }
            }
            httpPost.setEntity(new UrlEncodedFormEntity(nvps));
            //4、設置請求Headers
            if (headers != null && headers.keySet().size() > 0) {
                for (Map.Entry<String, String> entry : headers.entrySet()) {
                    httpPost.setHeader(entry.getKey(),entry.getValue());
                }
            }
            //5、執行POST方法，獲取響應結果
            response = httpclient.execute(httpPost);
            //6、獲取響應狀態碼
            StatusLine statusLine = response.getStatusLine();
            if (statusLine.getStatusCode() != 200) {
                logger.info("[doPost]request url:{} post params :{} statusCode:{} ", url, params, statusLine.getStatusCode());
                return null;
            }
            //6、獲取響應內容
            HttpEntity entity = response.getEntity();
            InputStream is = entity.getContent();
            //7、將字節流轉換成字符串
            StringBuilder sb = new StringBuilder();
            BufferedReader reader = new BufferedReader(new InputStreamReader(is));
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
            is.close();
            reader.close();
            result = sb.toString();
            EntityUtils.consume(entity);

            long end = System.currentTimeMillis();
            costTime = end - start;
            return result;
        } catch (ConnectTimeoutException e) {
            //連接超時異常需專門監控
            logger.warn("[doPost]Connect timed out service={},url={},params={},exception={}",service, url, params, e);
            return null;
        } catch (SocketTimeoutException e) {
            //Socket讀異常需專門監控
            logger.warn("[doPost]Read timed out service={},url={} params={} exception={}",service, url, params, e);
            return null;
        }
        catch (Exception e) {
            logger.warn("[doPost]request service={},url={} params={} exception={}",service, url, params, e);
            return null;
        } finally {
            //8、釋放連接
            try {
                if(response != null) {
                    response.close();
                }
                if(httpclient != null) {
                    httpclient.close();
                } catch (IOException e) {
                    logger.warn("[doPost]request url:{} params :{} close response exception", url, params);
                }
            logger.info("end http call service={},costTime={},method={},url={},params={},result={}", service, costTime, "post", url, params, result);
        }
    }