基于：httpclient 4.5.3
1、httpclient的获得
1.1 httpclients
static CloseableHttpClient createDefault()
Creates CloseableHttpClient instance with default configuration.
static CloseableHttpClient createMinimal()
Creates CloseableHttpClient instance that implements the most basic HTTP
protocol support.
static CloseableHttpClient createMinimal(HttpClientConnectionManager connManager)
Creates CloseableHttpClient instance that implements the most basic HTTP protocol support.
static CloseableHttpClient createSystem()
Creates CloseableHttpClient instance with default configuration based on ssytem properties.
static HttpClientBuilder custom()
Creates builder object for construction of custom CloseableHttpClient instances.--创建自定义的httpclient
1.2 httpclientUtils
static void closeQuietly(CloseableHttpResponse response)
Unconditionally close a response.
static void closeQuietly(HttpClient httpClient)
Unconditionally close a httpClient.
static void closeQuietly(org.apache.http.HttpResponse response)
Unconditionally close a response.
public static void closeQuietly(org.apache.http.HttpResponse response)
Unconditionally close a response.
Example Code:

HttpResponse httpResponse = null;
try {
httpResponse = httpClient.execute(httpGet);
} catch (Exception e) {
// error handling
} finally {
HttpClientUtils.closeQuietly(httpResponse);
}

Parameters:
response - the HttpResponse to release resources, may be null or already closed.
Since:
4.2