使用HttpClient4.5 PoolingHttpClientConnectionManager 提交Http请求

使用连接池的好处

大家都知道http连接是基于tcp的，而tcp创建连接需要三次握手，断开连接四次挥手，如果我们不使用连接池，那么每发出一个请求，就需要三次握手和四次挥手，而三次握手和四次挥手都是耗资源的操作。试想如果频繁的发出请求，性能是不是会是个瓶颈。所以HttpClient在4之后就出现了连接池的概念，当请求结束并不是直接断开连接，而是返回给连接池方便下次调用。

代码示例

    private static PoolingHttpClientConnectionManager clientConnectionManager=null;    private static CloseableHttpClient httpClient=null;    private static RequestConfig config = RequestConfig.custom().setCookieSpec(CookieSpecs.STANDARD_STRICT).build();    private final static Object syncLock = new Object();    /**     * 创建httpclient连接池并初始化     */     @PostConstruct    private void init(){        Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()                .register("https", SSLConnectionSocketFactory.getSocketFactory())                .register("http", PlainConnectionSocketFactory.getSocketFactory())                .build();        clientConnectionManager =new PoolingHttpClientConnectionManager(socketFactoryRegistry);        clientConnectionManager.setMaxTotal(50);        clientConnectionManager.setDefaultMaxPerRoute(25);    }    public static CloseableHttpClient getHttpClient(){        if(httpClient == null){            synchronized (syncLock){                if(httpClient == null){                      CookieStore cookieStore = new BasicCookieStore();                    BasicClientCookie cookie = new BasicClientCookie("sessionID", "######");                    cookie.setDomain("#####");                    cookie.setPath("/");                    cookieStore.addCookie(cookie);                    httpClient =HttpClients.custom().setConnectionManager(clientConnectionManager).setDefaultCookieStore(cookieStore).setDefaultRequestConfig(config).build();                }                }            }        }        return httpClient;    }    /**     * get请求     * @param url     * @param headers     * @return     */    public static HttpEntity httpGet(String url, Map<String,Object> headers){        CloseableHttpClient httpClient = getHttpClient();        HttpRequest httpGet = new HttpGet(url);        if(headers!=null&&!headers.isEmpty()){            httpGet = setHeaders(headers, httpGet);        }        CloseableHttpResponse response = null;        try{            response =httpClient.execute((HttpGet)httpGet);            HttpEntity entity = response.getEntity();            return entity;        }catch (Exception e){            e.printStackTrace();        }        return null;    }    /**     * post请求,使用json格式传参     * @param url     * @param headers     * @param data     * @return     */    public static HttpEntity httpPost(String url,Map<String,Object> headers,String data){        CloseableHttpClient httpClient = getHttpClient();        HttpRequest request = new HttpPost(url);        if(headers!=null&&!headers.isEmpty()){            request = setHeaders(headers,request);        }        CloseableHttpResponse response = null;        try {            HttpPost httpPost = (HttpPost) request;            httpPost.setEntity(new StringEntity(data, ContentType.create("application/json", "UTF-8")));            response=httpClient.execute(httpPost);            HttpEntity entity = response.getEntity();            return entity;        } catch (IOException e) {            e.printStackTrace();        }        return null;    }    /**    使用表单键值对传参    */    public static HttpEntity PostForm(String url,Map<String,Object> headers,List<NameValuePair> data){        CloseableHttpClient httpClient = getHttpClient();        HttpRequest request = new HttpPost(url);        if(headers!=null&&!headers.isEmpty()){            request = setHeaders(headers,request);        }        CloseableHttpResponse response = null;        UrlEncodedFormEntity uefEntity;        try {            HttpPost httpPost = (HttpPost) request;            uefEntity = new UrlEncodedFormEntity(data,"UTF-8");            httpPost.setEntity(uefEntity);           // httpPost.setEntity(new StringEntity(data, ContentType.create("application/json", "UTF-8")));            response=httpClient.execute(httpPost);            HttpEntity entity = response.getEntity();            return entity;        } catch (IOException e) {            e.printStackTrace();        }        return null;    }    /**     * 设置请求头信息     * @param headers     * @param request     * @return     */    private static HttpRequest setHeaders(Map<String,Object> headers, HttpRequest request) {        for (Map.Entry entry : headers.entrySet()) {            if (!entry.getKey().equals("Cookie")) {                request.addHeader((String) entry.getKey(), (String) entry.getValue());            } else {                Map<String, Object> Cookies = (Map<String, Object>) entry.getValue();                for (Map.Entry entry1 : Cookies.entrySet()) {                    request.addHeader(new BasicHeader("Cookie", (String) entry1.getValue()));                }            }        }        return request;    }    public static Map<String,String> getCookie(String url){        CloseableHttpClient httpClient = getHttpClient();        HttpRequest httpGet = new HttpGet(url);        CloseableHttpResponse response = null;        try{            response =httpClient.execute((HttpGet)httpGet);            Header[] headers = response.getAllHeaders();            Map<String,String> cookies=new HashMap<String, String>();            for(Header header:headers){                cookies.put(header.getName(),header.getValue());            }            return cookies;        }catch (Exception e){            e.printStackTrace();        }        return null;    }