httpclient连接池在ES Restful API请求中的应用

package com.wm.utils;import org.apache.http.impl.client.CloseableHttpClient;import org.apache.http.impl.client.HttpClients;import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;/** * 1.功能：http连接池 */public class HttpPoolManager {public static PoolingHttpClientConnectionManager clientConnectionManager = null;private int maxTotal = 50;private int defaultMaxPerRoute = 25;private HttpPoolManager(int maxTotal, int defaultMaxPerRoute) {this.maxTotal = maxTotal;this.defaultMaxPerRoute = defaultMaxPerRoute;clientConnectionManager.setMaxTotal(maxTotal);clientConnectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);}private HttpPoolManager() {clientConnectionManager.setMaxTotal(maxTotal);clientConnectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);}private static HttpPoolManager poolManager = null;/* * 获取实例1 */public synchronized static HttpPoolManager getInstance() {if (poolManager == null) {clientConnectionManager = new PoolingHttpClientConnectionManager();poolManager = new HttpPoolManager();}return poolManager;}/* * 获取实例1 */public synchronized static HttpPoolManager getInstance(int maxTotal, int defaultMaxPerRoute) {if (poolManager == null) {poolManager = new HttpPoolManager(maxTotal, defaultMaxPerRoute);}return poolManager;}/* * 获取CloseableHttpClient */public static CloseableHttpClient getHttpClient() {if (clientConnectionManager == null) {clientConnectionManager = new PoolingHttpClientConnectionManager();getInstance();}return HttpClients.custom().setConnectionManager(clientConnectionManager).build();}}

为什么使用httpclient连接池？

最近在使用ES做全文搜索，使用的restful api操作，最初没有使用httpclient连接池，这样导致每次请求都重建一个httpclient实例，es服务器报如下异常：

[2017-07-19T13:44:14,768][WARN ][o.e.h.n.Netty4HttpServerTransport] [gxKNWf3] caught exception while handling client http traffic, closing connection [id: 0xe0578a52, L:/127.0.0.1:9200 - R:/127.0.0.1:49956]java.io.IOException: 远程主机强迫关闭了一个现有的连接。at sun.nio.ch.SocketDispatcher.read0(Native Method) ~[?:?]at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:43) ~[?:?]at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223) ~[?:?]at sun.nio.ch.IOUtil.read(IOUtil.java:197) ~[?:?]at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380) ~[?:?]at io.netty.buffer.PooledHeapByteBuf.setBytes(PooledHeapByteBuf.java:261) ~[netty-buffer-4.1.11.Final.jar:4.1.11.Final]at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:1100) ~[netty-buffer-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:372) ~[netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:123) [netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:644) [netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:544) [netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:498) [netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:458) [netty-transport-4.1.11.Final.jar:4.1.11.Final]at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:858) [netty-common-4.1.11.Final.jar:4.1.11.Final]at java.lang.Thread.run(Thread.java:745) [?:1.8.0_112]

使用连接池后，避免了此类异常。