首先,明確兩點(diǎn):
1.http連接池不是萬能的,過多的長連接會占用服務(wù)器資源,導(dǎo)致其他服務(wù)受阻
2.http連接池只適用于請求是經(jīng)常訪問同一主機(jī)(或同一個接口)的情況下
3.并發(fā)數(shù)不高的情況下資源利用率低下
那么,當(dāng)你的業(yè)務(wù)符合上面3點(diǎn),那么你可以考慮使用http連接池來提高服務(wù)器性能
使用http連接池的優(yōu)點(diǎn):
1.復(fù)用http連接,省去了tcp的3次握手和4次揮手的時(shí)間,極大降低請求響應(yīng)的時(shí)間
2.自動管理tcp連接,不用人為地釋放/創(chuàng)建連接
使用http連接池的大致流程 :
1.創(chuàng)建PoolingHttpClientConnectionManager實(shí)例
2.給manager設(shè)置參數(shù)
3.給manager設(shè)置重試策略
4.給manager設(shè)置連接管理策略
5.開啟監(jiān)控線程,及時(shí)關(guān)閉被服務(wù)器單向斷開的連接
6.構(gòu)建HttpClient實(shí)例
7.創(chuàng)建HttpPost/HttpGet實(shí)例,并設(shè)置參數(shù)
8.獲取響應(yīng),做適當(dāng)?shù)奶幚?br>
9.將用完的連接放回連接池
public class HttpConnectionPoolUtil {
private static Logger logger = LoggerFactory.getLogger(HttpConnectionPoolUtil.class);
private static final int CONNECT_TIMEOUT = Config.getHttpConnectTimeout();// 設(shè)置連接建立的超時(shí)時(shí)間為10s
private static final int SOCKET_TIMEOUT = Config.getHttpSocketTimeout();
private static final int MAX_CONN = Config.getHttpMaxPoolSize(); // 最大連接數(shù)
private static final int Max_PRE_ROUTE = Config.getHttpMaxPoolSize();
private static final int MAX_ROUTE = Config.getHttpMaxPoolSize();
private static CloseableHttpClient httpClient; // 發(fā)送請求的客戶端單例
private static PoolingHttpClientConnectionManager manager; //連接池管理類
private static ScheduledExecutorService monitorExecutor;
private final static Object syncLock = new Object(); // 相當(dāng)于線程鎖,用于線程安全
/**
* 對http請求進(jìn)行基本設(shè)置
* @param httpRequestBase http請求
*/
private static void setRequestConfig(HttpRequestBase httpRequestBase){
RequestConfig requestConfig = RequestConfig.custom().setConnectionRequestTimeout(CONNECT_TIMEOUT)
.setConnectTimeout(CONNECT_TIMEOUT)
.setSocketTimeout(SOCKET_TIMEOUT).build();
httpRequestBase.setConfig(requestConfig);
}
public static CloseableHttpClient getHttpClient(String url){
String hostName = url.split("/")[2];
System.out.println(hostName);
int port = 80;
if (hostName.contains(":")){
String[] args = hostName.split(":");
hostName = args[0];
port = Integer.parseInt(args[1]);
}
if (httpClient == null){
//多線程下多個線程同時(shí)調(diào)用getHttpClient容易導(dǎo)致重復(fù)創(chuàng)建httpClient對象的問題,所以加上了同步鎖
synchronized (syncLock){
if (httpClient == null){
httpClient = createHttpClient(hostName, port);
//開啟監(jiān)控線程,對異常和空閑線程進(jìn)行關(guān)閉
monitorExecutor = Executors.newScheduledThreadPool(1);
monitorExecutor.scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
//關(guān)閉異常連接
manager.closeExpiredConnections();
//關(guān)閉5s空閑的連接
manager.closeIdleConnections(Config.getHttpIdelTimeout(), TimeUnit.MILLISECONDS);
logger.info("close expired and idle for over 5s connection");
}
}, Config.getHttpMonitorInterval(), Config.getHttpMonitorInterval(), TimeUnit.MILLISECONDS);
}
}
}
return httpClient;
}
/**
* 根據(jù)host和port構(gòu)建httpclient實(shí)例
* @param host 要訪問的域名
* @param port 要訪問的端口
* @return
*/
public static CloseableHttpClient createHttpClient(String host, int port){
ConnectionSocketFactory plainSocketFactory = PlainConnectionSocketFactory.getSocketFactory();
LayeredConnectionSocketFactory sslSocketFactory = SSLConnectionSocketFactory.getSocketFactory();
Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory> create().register("http", plainSocketFactory)
.register("https", sslSocketFactory).build();
manager = new PoolingHttpClientConnectionManager(registry);
//設(shè)置連接參數(shù)
manager.setMaxTotal(MAX_CONN); // 最大連接數(shù)
manager.setDefaultMaxPerRoute(Max_PRE_ROUTE); // 路由最大連接數(shù)
HttpHost httpHost = new HttpHost(host, port);
manager.setMaxPerRoute(new HttpRoute(httpHost), MAX_ROUTE);
//請求失敗時(shí),進(jìn)行請求重試
HttpRequestRetryHandler handler = new HttpRequestRetryHandler() {
@Override
public boolean retryRequest(IOException e, int i, HttpContext httpContext) {
if (i > 3){
//重試超過3次,放棄請求
logger.error("retry has more than 3 time, give up request");
return false;
}
if (e instanceof NoHttpResponseException){
//服務(wù)器沒有響應(yīng),可能是服務(wù)器斷開了連接,應(yīng)該重試
logger.error("receive no response from server, retry");
return true;
}
if (e instanceof SSLHandshakeException){
// SSL握手異常
logger.error("SSL hand shake exception");
return false;
}
if (e instanceof InterruptedIOException){
//超時(shí)
logger.error("InterruptedIOException");
return false;
}
if (e instanceof UnknownHostException){
// 服務(wù)器不可達(dá)
logger.error("server host unknown");
return false;
}
if (e instanceof ConnectTimeoutException){
// 連接超時(shí)
logger.error("Connection Time out");
return false;
}
if (e instanceof SSLException){
logger.error("SSLException");
return false;
}
HttpClientContext context = HttpClientContext.adapt(httpContext);
HttpRequest request = context.getRequest();
if (!(request instanceof HttpEntityEnclosingRequest)){
//如果請求不是關(guān)閉連接的請求
return true;
}
return false;
}
};
CloseableHttpClient client = HttpClients.custom().setConnectionManager(manager).setRetryHandler(handler).build();
return client;
}
/**
* 設(shè)置post請求的參數(shù)
* @param httpPost
* @param params
*/
private static void setPostParams(HttpPost httpPost, Map<String, String> params){
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
Set<String> keys = params.keySet();
for (String key: keys){
nvps.add(new BasicNameValuePair(key, params.get(key)));
}
try {
httpPost.setEntity(new UrlEncodedFormEntity(nvps, "utf-8"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
public static JsonObject post(String url, Map<String, String> params){
HttpPost httpPost = new HttpPost(url);
setRequestConfig(httpPost);
setPostParams(httpPost, params);
CloseableHttpResponse response = null;
InputStream in = null;
JsonObject object = null;
try {
response = getHttpClient(url).execute(httpPost, HttpClientContext.create());
HttpEntity entity = response.getEntity();
if (entity != null) {
in = entity.getContent();
String result = IOUtils.toString(in, "utf-8");
Gson gson = new Gson();
object = gson.fromJson(result, JsonObject.class);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try{
if (in != null) in.close();
if (response != null) response.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return object;
}
/**
* 關(guān)閉連接池
*/
public static void closeConnectionPool(){
try {
httpClient.close();
manager.close();
monitorExecutor.shutdown();
} catch (IOException e) {
e.printStackTrace();
}
}
}
關(guān)鍵的地方有以下幾點(diǎn):
1.httpclient實(shí)例必須是單例,且該實(shí)例必須使用HttpClients.custom().setConnectionManager()來綁定一個PollingHttpClientConnectionManager,這樣該client每次發(fā)送請求都會通過manager來獲取連接,如果連接池中沒有可用連接的話,則該會阻塞線程,直到有可用的連接
2.httpclients4.5.x版本直接調(diào)用ClosableHttpResponse.close()就能直接把連接放回連接池,而不是關(guān)閉連接,以前的版本貌似要調(diào)用其他方法才能把連接放回連接池
3.由于服務(wù)器一般不會允許無限期的長連接,所以需要開啟監(jiān)控線程,每隔一段時(shí)間就檢測一下連接池中連接的情況,及時(shí)關(guān)閉異常連接和長時(shí)間空閑的連接,避免占用服務(wù)器資源.
