springboot 引入 restTempalte

1.maven依赖

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.6</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

2.连接池配置

#最大连接数
http:
  maxTotal: 100
  #并发数
  defaultMaxPerRoute: 20
  #创建连接的最长时间
  connectTimeout: 1000
  #从连接池中获取到连接的最长时间
  connectionRequestTimeout: 500
  #数据传输的最长时间
  socketTimeout: 10000
  #提交请求前测试连接是否可用
  staleConnectionCheckEnabled: true
  #可用空闲连接过期时间,重用空闲连接时会先检查是否空闲时间超过这个时间，如果超过，释放socket重新建立
  validateAfterInactivity: 3000000

3.连接池初始化

package cn.likui.study.config;

import org.apache.http.client.HttpClient;
import org.apache.http.client.config.RequestConfig;
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.SSLConnectionSocketFactory;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

/** 
* @Description: https://www.cnblogs.com/yuexiaoyun/articles/13034028.html
* @Author: ldg
* @Date: 2020/10/9 
*/ 
@Configuration
public class RestTemplateConfig {
    @Value("${http.maxTotal}")
    private Integer maxTotal;

    @Value("${http.defaultMaxPerRoute}")
    private Integer defaultMaxPerRoute;

    @Value("${http.connectTimeout}")
    private Integer connectTimeout;

    @Value("${http.connectionRequestTimeout}")
    private Integer connectionRequestTimeout;

    @Value("${http.socketTimeout}")
    private Integer socketTimeout;

    @Value("${http.staleConnectionCheckEnabled}")
    private boolean staleConnectionCheckEnabled;

    @Value("${http.validateAfterInactivity}")
    private Integer validateAfterInactivity;


    @Bean
    public RestTemplate restTemplate() {
        return new RestTemplate(httpRequestFactory());
    }

    @Bean
    public ClientHttpRequestFactory httpRequestFactory() {
        return new HttpComponentsClientHttpRequestFactory(httpClient());
    }

    @Bean
    public HttpClient httpClient() {
        Registry<ConnectionSocketFactory> registry = RegistryBuilder.<ConnectionSocketFactory>create()
                .register("http", PlainConnectionSocketFactory.getSocketFactory())
                .register("https", SSLConnectionSocketFactory.getSocketFactory())
                .build();
        PoolingHttpClientConnectionManager connectionManager = new PoolingHttpClientConnectionManager(registry);
        // 最大连接数
        connectionManager.setMaxTotal(maxTotal);
        //单个路由最大连接数
        connectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);
        // 最大空间时间
        connectionManager.setValidateAfterInactivity(validateAfterInactivity);
        RequestConfig requestConfig = RequestConfig.custom()
                //服务器返回数据(response)的时间，超过抛出read timeout
                .setSocketTimeout(socketTimeout)
                //连接上服务器(握手成功)的时间，超出抛出connect timeout
                .setConnectTimeout(connectTimeout)
                // 提交前检测是否可用
                .setStaleConnectionCheckEnabled(staleConnectionCheckEnabled)
                //从连接池中获取连接的超时时间，超时间未拿到可用连接，会抛出org.apache.http.conn.ConnectionPoolTimeoutException: Timeout waiting for connection from pool
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .build();
        return HttpClientBuilder.create()
                .setDefaultRequestConfig(requestConfig)
                .setConnectionManager(connectionManager)
                .build();
    }

}

4.示例

    @RequestMapping("/testRestTemplate")
    @ResponseBody
    public Object testRestTemplate() throws IOException {
        ResponseEntity result= restTemplate.getForEntity("http://192.168.1.100:8080/User/getAllUser",ResponseEntity.class);
        return result.getBody();
    }

感谢：https://www.cnblogs.com/yuexiaoyun/articles/13034028.html