restTemplate踩过的坑-spring clound

现在公司项目基本都从臃肿的项目转换成微服务的方向转换，因此也从中使用了spring clound的一些组件，在此过程中就遇到了restTemplate的坑。

起初，是直接注入RestTemplate，后来则不断的遇到错误日志无法请求，出现异常。

异常信息：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.IllegalStateException: No instances available for IP

意思是说url必须是服务的名称，猜测应该是涉及到eureka，直接用ip跟url调用是直接报错的。

因此不适用默认的，直接重新自定义，则引用了原有的注入修改一下。

/**
 * 
 * 功能描述：
 * 
 * @作者 jimw 创建时间：2018-04
 *
 */
@Configuration
public class RestTemplateConfig {

	public RestTemplate restTemplate() {
		return new RestTemplate(getClientHttpRequestFactory());
	}

	/**
	 * 配置HttpClient超时时间
	 * 
	 * @return
	 */
	private ClientHttpRequestFactory getClientHttpRequestFactory() {
		RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(HTTP_SOCKET_TIMEOUT)
				.setConnectTimeout(HTTP_CONNECT_TIMEOUT).build();
		CloseableHttpClient client = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).build();
		return new HttpComponentsClientHttpRequestFactory(client);
	}

	/** http请求socket连接超时时间,毫秒为单位 */
	public static final int HTTP_SOCKET_TIMEOUT = 15000;

	/** http请求连接超时时间,毫秒为单位 */
	public static final int HTTP_CONNECT_TIMEOUT = 15000;
}

　　

当配置了这个之后，服务正常了。观察了一段时间，发现在并发的高峰期，开多几个服务器负载，也会存在服务出现请求非常慢，导致接口出现阻塞的情况出现，经过分析

1、出现阻塞的原因是因为高峰并发的时候，出现请求的链接数很大

因此找了源码，发现是因为restTemplate的默认配置值小于请求的链接数，而且路由并发也是默认为5的,因为微服务之间的逻辑处理中也有一定的时间。出现大规模阻塞的坑就这么踩到了。 

 

对代码改造一下，配置最大链接数，路由并发数，这个restTemplate的坑就这么解决了。

package com.jingbei.guess.config.web;

import java.security.KeyManagementException;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;

import org.apache.http.client.HttpClient;
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.PlainConnectionSocketFactory;
import org.apache.http.conn.ssl.NoopHostnameVerifier;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContextBuilder;
import org.apache.http.conn.ssl.TrustStrategy;
import org.apache.http.impl.client.DefaultHttpRequestRetryHandler;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.DefaultResponseErrorHandler;
import org.springframework.web.client.RestTemplate;

import lombok.extern.slf4j.Slf4j;

/**
 * 
 * 功能描述：
 * 
 * @作者 jimw 创建时间： 2018-04
 *
 */
@Slf4j
@Configuration
public class RestTemplateConfig {
	@Bean
	public RestTemplate restTemplate() {
		RestTemplate restTemplate = new RestTemplate();
		restTemplate.setRequestFactory(clientHttpRequestFactory());
		restTemplate.setErrorHandler(new DefaultResponseErrorHandler());
		return restTemplate;
	}

	@Bean
	public HttpComponentsClientHttpRequestFactory clientHttpRequestFactory() {
		try {
			HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
			SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, new TrustStrategy() {
				public boolean isTrusted(X509Certificate[] arg0, String arg1) throws CertificateException {
					return true;
				}
			}).build();
			httpClientBuilder.setSSLContext(sslContext);
			HostnameVerifier hostnameVerifier = NoopHostnameVerifier.INSTANCE;
			SSLConnectionSocketFactory sslConnectionSocketFactory = new SSLConnectionSocketFactory(sslContext,
					hostnameVerifier);
			Registry<ConnectionSocketFactory> socketFactoryRegistry = RegistryBuilder.<ConnectionSocketFactory>create()
					.register("http", PlainConnectionSocketFactory.getSocketFactory())
					.register("https", sslConnectionSocketFactory).build();// 注册http和https请求
			// 开始设置连接池
			PoolingHttpClientConnectionManager poolingHttpClientConnectionManager = new PoolingHttpClientConnectionManager(
					socketFactoryRegistry);
			poolingHttpClientConnectionManager.setMaxTotal(2700); // 最大连接数2700
			poolingHttpClientConnectionManager.setDefaultMaxPerRoute(100); // 同路由并发数100
			httpClientBuilder.setConnectionManager(poolingHttpClientConnectionManager);
			httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(3, true)); // 重试次数
			HttpClient httpClient = httpClientBuilder.build();
			HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory(
					httpClient); // httpClient连接配置
			clientHttpRequestFactory.setConnectTimeout(20000); // 连接超时
			clientHttpRequestFactory.setReadTimeout(30000); // 数据读取超时时间
			clientHttpRequestFactory.setConnectionRequestTimeout(20000); // 连接不够用的等待时间
			return clientHttpRequestFactory;
		} catch (KeyManagementException | NoSuchAlgorithmException | KeyStoreException e) {
			log.error("初始化HTTP连接池出错", e);
		}
		return null;
	}

}

　　在对应的插件中配置即可

依赖包：

<dependency>

<groupId>org.apache.httpcomponents</groupId>

<artifactId>httpclient</artifactId>

<version>4.5.3</version>

</dependency>

<dependency>

<groupId>org.apache.httpcomponents</groupId>

<artifactId>httpcore</artifactId>

<version>4.4.9</version>

</dependency>