标签：lis rac style trace 关闭 pac tde etc i++
1、降低延迟：如果不采用连接池，每次连接发起Http请求的时候都会重新建立TCP连接(经历3次握手)，用完就会关闭连接(4次挥手)，如果采用连接池则减少了这部分时间损耗，别小看这几次握手，本人经过测试发现，基本上3倍的时间延迟
2、支持更大的并发：如果不采用连接池，每次连接都会打开一个端口，在大并发的情况下系统的端口资源很快就会被用完，导致无法建立新的连接
连接池管理器代码
import org.apache.http.config.Registry; import org.apache.http.config.RegistryBuilder; import org.apache.http.conn.socket.ConnectionSocketFactory; import org.apache.http.conn.socket.LayeredConnectionSocketFactory; import org.apache.http.conn.socket.PlainConnectionSocketFactory; import org.apache.http.conn.ssl.SSLConnectionSocketFactory; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.impl.conn.PoolingHttpClientConnectionManager; import javax.annotation.PostConstruct; import javax.net.ssl.SSLContext; import java.security.NoSuchAlgorithmException; public class HttpConnectionManager { PoolingHttpClientConnectionManager cm = null; @PostConstruct public void init() { LayeredConnectionSocketFactory sslsf = null; try { sslsf = new SSLConnectionSocketFactory(SSLContext.getDefault()); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory> create() .register("https", sslsf) .register("http", new PlainConnectionSocketFactory()) .build(); cm =new PoolingHttpClientConnectionManager(socketFactoryRegistry); cm.setMaxTotal(200); cm.setDefaultMaxPerRoute(20); } public CloseableHttpClient getHttpClient() { CloseableHttpClient httpClient = HttpClients.custom() .setConnectionManager(cm) .build(); /*CloseableHttpClient httpClient = HttpClients.createDefault();//如果不采用连接池就是这种方式获取连接*/ return httpClient; } }
使用连接池代码
private static CloseableHttpClient getHttpClient(){ HttpConnectionManager httpConnectionManager= (HttpConnectionManager) AppBeanUtil.getBean("httpConnectionManager"); return httpConnectionManager.getHttpClient(); }
获取连接
public static String getFromUrl(String url, Map<String, String> params,String charset) throws Exception { if(StringUtil.isEmpty(charset)){ charset=defaultCharset; } CloseableHttpClient httpclient = getHttpClient(); URIBuilder uriBuilder = new URIBuilder(url); uriBuilder.setCharset(Charset.forName(charset)); if(params!=null){ Iterator<String> keyIt = params.keySet().iterator(); while (keyIt.hasNext()) { String key = keyIt.next(); String val = params.get(key); uriBuilder.setParameter(key, val); } } URI uri = uriBuilder.build(); HttpGet httpget = new HttpGet(uri); CloseableHttpResponse response = httpclient.execute(httpget); try { HttpEntity entity = response.getEntity(); if (entity != null) { String content=getContent(entity.getContent()); return content; } } finally { response.close(); } return null; }
访问url 获取内容
private static String getContent(InputStream instream) throws IOException { StringWriter writer = new StringWriter(); IOUtils.copy(instream, writer, defaultCharset); instream.close(); return writer.toString(); }
读取数据，这里 instream 需要进行关闭。
测试连接池和不使用连接池的效率测试。
@Test public void postTest() throws Exception { long start=System.currentTimeMillis(); for (int i = 0; i < 200; i++) { String content=HttpClientPoolUtil.postFromUrl("https://www.cnblogs.com/kingszelda/p/8988505.html",new HashMap<>()); } System.err.println("---------------------------postTest---------------------------"); System.err.println(System.currentTimeMillis()-start); System.err.println("---------------------------postTest---------------------------"); start=System.currentTimeMillis(); for (int i = 0; i < 200; i++) { String content= HttpClientUtil.postFromUrl("https://www.cnblogs.com/kingszelda/p/8988505.html",new HashMap<>()); } System.err.println(System.currentTimeMillis()-start); }
测试结果
---------------------------postTest---------------------------
9791
---------------------------postTest---------------------------
39427
可以看到在使用连接池访问两百次花费时间为 9.7秒，不使用连接池为 39.4秒，时间相差为30秒。
通过计算从发送请求到接收请求约花48毫秒，每建立一次连接需要花费的时间为150毫秒，可见创建连接是需要非常消耗性能的。
标签：lis rac style trace 关闭 pac tde etc i++
原文地址：https://www.cnblogs.com/yg_zhang/p/12239409.html
