配置 http 连接池：

# 在 spring-context.xml 配置文件中引入

<import resource="classpath:spring/spring-httpclient.xml" />

# 连接池配置文件 spring-httpclient.xml

	<?xml version="1.0" encoding="UTF-8"?>
	<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://www.springframework.org/schema/beans
	http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

	<!-- 配置一个 httpClient 连接池 -->
	<bean id="poolHttpClientConnectionManager"
	class="org.apache.http.impl.conn.PoolingHttpClientConnectionManager">
	<!-- 最大链接数 -->
	<property name="maxTotal" value="200"/>
	<!-- 设置每个主机地址的并发数 -->
	<property name="defaultMaxPerRoute" value="20"/>
	</bean>

	<!-- 生成 httpClientBuilder (用于得到 httpClient) -->
	<bean id="httpClientBuilder" class="org.apache.http.impl.client.HttpClientBuilder">
	<!-- 注入连接池 -->
	<property name="connectionManager" ref="poolingHttpClientConnectionManager"/>
	</bean>

	<!-- 配置 httpClient (通过 httpClientBuilder 得到 httpClient 对象，并且要设置 httpClient 为多利模式) -->
	<bean class="org.apache.http.impl.client.CloseableHttpClient"
	factory-bean="httpClientBuilder" factory-method="build" scope="prototype"></bean>

	<!-- 构造 (配置) 请求参数 -->
	<bean id="requestConfigBuilder" class="org.apache.http.client.config.RequestConfig.Builder">
	<!-- 创建连接的最长时间 -->
	<property name="connectTimeout" value="1000"/>
	<!-- 从连接池中获取到连接的最长时间 -->
	<property name="socketTimeout" value="10000"/>
	<!-- 提交请求前测试连接是否可用 -->
	<property name="connectionRequestTimeout" value="500"/>
	</bean>

	<bean class="org.apache.http.client.config.RequestConfig"
	factory-bean="requestConfigBuilder" factory-method="build"></bean>

	<!-- 定期清理无效的连接 -->
	<bean class="com.a.b.common.utils.http.IdleConnectionEvictor" destroy-method="shutdown">
	<constructor-arg index="0" ref="poolingHttpClientConnectionManager" />
	<!-- 间隔一分钟清理一次 -->
	<constructor-arg index="1" value="60000" />
	</bean>

	</beans>

# 类 IdleConnectionEvictor

	public class IdleConnectionEvictor extends Thread{

	private final HttpClientConnectionManager connMgr;

	private Integer waitTime;

	private volatile boolean shutdown;

	private static final Logger logger = Logger.getLogger(HttpPoolUtil.class);

	public IdleConnectionEvictor(HttpClientConnectionManager connMgr, Integer waitTime) {
	this.connMgr = connMgr;
	this.waitTime = waitTime;
	this.start();
	}

	@Override
	public void run() {
	try {
	while (!shutdown) {
	synchronized (this) {
	wait(waitTime);
	// 关闭失效的连接
	connMgr.closeExpiredConnections();
	}
	}
	} catch (InterruptedException ex) {
	logger.error("清理异常");
	}
	}

	/**
	* 销毁释放资源
	*/
	public void shutdown() {
	shutdown = true;
	synchronized (this) {
	notifyAll();
	}
	}
	}