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(){
try {
//添加对https的支持，该sslContext没有加载客户端证书
// 如果需要加载客户端证书，请使用如下sslContext,其中KEYSTORE_FILE和KEYSTORE_PASSWORD分别是你的证书路径和证书密码
//KeyStore keyStore = KeyStore.getInstance(KeyStore.getDefaultType()
//FileInputStream instream = new FileInputStream(new File(KEYSTORE_FILE));
//keyStore.load(instream, KEYSTORE_PASSWORD.toCharArray());
//SSLContext sslContext = SSLContexts.custom().loadKeyMaterial(keyStore,KEYSTORE_PASSWORD.toCharArray())
// .loadTrustMaterial(null, new TrustSelfSignedStrategy())
//.build();
SSLContext sslContext = SSLContexts.custom()
.loadTrustMaterial(null, new TrustSelfSignedStrategy())
.build();
SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext,SSLConnectionSocketFactory.getDefaultHostnameVerifier());
Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
.register("https", sslsf)
.register("http", PlainConnectionSocketFactory.getSocketFactory())
.build();
clientConnectionManager = new PoolingHttpClientConnectionManager(socketFactoryRegistry);
clientConnectionManager.setMaxTotal(50);
clientConnectionManager.setDefaultMaxPerRoute(25);
}catch (Exception e){
LOGGER.warn("httpUtils init get exception:",e);
}
}
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;
}