近段时间需要优化原有的http调用，原有的http调用是直接使用HttpClient进行调用，没有交给spring去管理，也没有清理过期链接的线程，这里记录下使用springboot如何配置HttpClient。下面直接放代码。

①httpclient配置类，在其中可以配置http连接池最大链接数，并发数，超时时间，代理等。

import org.apache.http.client.config.RequestConfig;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClientBuilder;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class HttpClientConfig {
    private static final Logger logger = LoggerFactory.getLogger(HttpClientConfig.class);

    @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;

    /**
     * 首先实例化一个连接池管理器，设置最大连接数、并发连接数
     *
     * @return
     */
    @Bean(name = "httpClientConnectionManager")
    public PoolingHttpClientConnectionManager getHttpClientConnectionManager() {
        PoolingHttpClientConnectionManager httpClientConnectionManager = new PoolingHttpClientConnectionManager();
        //最大连接数
        httpClientConnectionManager.setMaxTotal(maxTotal);
        //并发数
        httpClientConnectionManager.setDefaultMaxPerRoute(defaultMaxPerRoute);
        return httpClientConnectionManager;
    }

    /**
     * 实例化连接池，设置连接池管理器。
     * 这里需要以参数形式注入上面实例化的连接池管理器
     *
     * @param httpClientConnectionManager
     * @return
     */
    @Bean(name = "httpClientBuilder")
    public HttpClientBuilder getHttpClientBuilder(@Qualifier("httpClientConnectionManager") PoolingHttpClientConnectionManager httpClientConnectionManager) {

        //HttpClientBuilder中的构造方法被protected修饰，所以这里不能直接使用new来实例化一个HttpClientBuilder，可以使用HttpClientBuilder提供的静态方法create()来获取HttpClientBuilder对象
        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();

        httpClientBuilder.setConnectionManager(httpClientConnectionManager);

        return httpClientBuilder;
    }

    /**
     * 注入连接池，用于获取httpClient
     *
     * @param httpClientBuilder
     * @return
     */
    @Bean(name = "httpClient")
    public CloseableHttpClient getCloseableHttpClient(@Qualifier("httpClientBuilder") HttpClientBuilder httpClientBuilder) {
        return httpClientBuilder.build();
    }

    /**
     * Builder是RequestConfig的一个内部类
     * 通过RequestConfig的custom方法来获取到一个Builder对象
     * 设置builder的连接信息
     * 这里还可以设置proxy，cookieSpec等属性。有需要的话可以在此设置
     *
     * @return
     */
    @Bean(name = "builder")
    public RequestConfig.Builder getBuilder() {
        RequestConfig.Builder builder = RequestConfig.custom();
        return builder.setConnectTimeout(connectTimeout)
                .setConnectionRequestTimeout(connectionRequestTimeout)
                .setSocketTimeout(socketTimeout);
    }

    /**
     * 使用builder构建一个RequestConfig对象
     *
     * @param builder
     * @return
     */
    @Bean
    public RequestConfig getRequestConfig(@Qualifier("builder") RequestConfig.Builder builder) {
        return builder.build();
    }
}

②清理失效的http链接

@Component
public class IdleConnectionEvictor extends Thread {

    @Autowired
    private HttpClientConnectionManager httpClientConnectionManager;

    private volatile boolean shutdown;

    public IdleConnectionEvictor() {
        super();
        super.start();
    }

    @Override
    public void run() {
        try {
            while (!shutdown) {
                synchronized (this) {
                    wait(5000);
                    // 关闭失效的连接
                    httpClientConnectionManager.closeExpiredConnections();

                    httpClientConnectionManager.closeIdleConnections(30L, TimeUnit.SECONDS);
                }
            }
        } catch (InterruptedException ex) {
            // 结束
        }
    }

    //关闭清理无效连接的线程
    public void shutdown() {
        shutdown = true;
        synchronized (this) {
            notifyAll();
        }
    }
}

③进行调用，这里暂时提供get请求，post请求可以自己封装

@Service
public class HttpClientService {
    private static final Logger logger = LoggerFactory.getLogger(HttpClientService.class);

    @Autowired
    private CloseableHttpClient httpClient;
    @Autowired
    private RequestConfig requestConfig;

    /**
     * get请求
     *
     * @return
     */
    public String doGet(String url, String charset) {
        CloseableHttpResponse response = null;
        try {
            //发送get请求
            HttpGet request = new HttpGet(url);
            request.setConfig(requestConfig);
            response = httpClient.execute(request);

            /**请求发送成功，并得到响应**/
            if (response.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {
                /**读取服务器返回过来的json字符串数据**/
                String strResult = EntityUtils.toString(response.getEntity());
                strResult = new String(strResult.getBytes(charset), "utf-8");
                return strResult;
            }
        } catch (IOException e) {
            logger.error("http调用出错:{}",e.getMessage())
        } finally {
            try {
                if (response != null){
                    response.close();
                }
            }catch (IOException e){
                logger.error("关闭链接出错:{}",e.getMessage());
            }
        }
        return null;
    }
}

④配置文件

#http配置服务
#最大连接数
http.maxTotal = 300
#并发数
http.defaultMaxPerRoute = 300
#创建连接的最长时间
http.connectTimeout=3000
#从连接池中获取到连接的最长时间
http.connectionRequestTimeout=1000
#数据传输的最长时间
http.socketTimeout=3000