httpclient请求转发实战

代码需求

公司有eureka管理页面、spring admin管理页面、kafka管理页面、日志查询页面和文件系统查询页面，现在要将这些页面放到一个统一的网页中管理，通过标签分别跳转到不同的页面，省去了分别点开的麻烦

这些单个的系统外网访问不到，但是我这个系统（manage）能够被外网访问，需要在后台做请求转发功能：

• 1 manage前台发送请求给后台
• 2 manage后台拿到传过来的参数和请求地址，使用httpclient请求内网eureka等
• 3 将返回的数据返回到前台

依赖地址

<dependency>
    <groupId>org.apache.httpcomponentsgroupId>
    <artifactId>httpclientartifactId>
    <version>4.5.2version>
dependency>

httpclient连接池

/**
  * http连接池配置
  * @author piper
  * @date 2018/7/4 13:15
  */
@Configuration
public class ConnectionManager {

    // 最大连接数
    private static final int MAX_TOTAL = 200;
    // 每一个路由的最大连接数
    private static final int MAX_PER_ROUTE = 500;
    //从连接池中获得连接的超时时间
    private static final int CONNECTION_REQUEST_TIMEOUT = 3000;
    //连接超时
    private static final int CONNECTION_TIMEOUT = 3000;
    //获取数据的超时时间
    private static final int SOCKET_TIMEOUT = 5000;

    private PoolingHttpClientConnectionManager cm;
    private CloseableHttpClient httpClient;

    /**
     * 重连接策略
     */
    HttpRequestRetryHandler retryHandler = (IOException exception, int executionCount, HttpContext context) -> {
        if (executionCount >= 3) {
            // Do not retry if over max retry count
            return false;
        }
        if (exception instanceof InterruptedIOException) {
            // Timeout
            return false;
        }
        if (exception instanceof UnknownHostException) {
            // Unknown host
            return false;
        }
        if (exception instanceof ConnectTimeoutException) {
            // Connection refused
            return false;
        }
        if (exception instanceof SSLException) {
            // SSL handshake exception
            return false;
        }
        
        HttpClientContext clientContext = HttpClientContext.adapt(context);
        HttpRequest request = clientContext.getRequest();
        boolean idempotent = !(request instanceof HttpEntityEnclosingRequest);
        if (idempotent) {
            // Retry if the request is considered idempotent
            return true;
        }
        return false;
    };

    /**
     * 配置连接参数
     */
    RequestConfig requestConfig = RequestConfig.custom()
        .setConnectionRequestTimeout(CONNECTION_REQUEST_TIMEOUT)
        .setConnectTimeout(CONNECTION_TIMEOUT)
        .setSocketTimeout(SOCKET_TIMEOUT)
        .build();

    public ConnectionManager() {
        cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(MAX_TOTAL);
        cm.setDefaultMaxPerRoute(MAX_PER_ROUTE);

        // 定制实现HttpClient，全局只有一个HttpClient
        httpClient = HttpClients.custom()
            .setConnectionManager(cm)
            .setDefaultRequestConfig(requestConfig)
            .setRetryHandler(retryHandler)
            .build();
    }

    @Bean
    public CloseableHttpClient getHttpClient() {
        return httpClient;
    }

}

一次请求的流程（请予以重视）

• 1 创建HttpPost或HttpGet方法
• 2 将请求参数放入方法内
• 3 设置方法的请求头，比如：Content-Type（这个尽量带上）
• 4 httpclient对象拿着HttpPost去请求
• 5 返回CloseableHttpResponse对象，数据都在这里了，仔细观察

入门demo

try {
    HttpClient client = HttpClients.createDefault();            //client对象
    HttpGet get = new HttpGet("http://localhost:8080/test");    //创建get请求
    CloseableHttpResponse response = httpClient.execute(get);   //执行get请求
    String mes = EntityUtils.toString(response.getEntity());    //将返回体的信息转换为字符串
    System.out.println(mes);
} catch (ClientProtocolException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

如何处理前台传入的参数

烦请移步 https://blog.csdn.net/GY325416/article/details/81413177

如何处理返回数据

参考另一篇博客 https://blog.csdn.net/GY325416/article/details/81436078

代码地址

https://download.csdn.net/download/gy325416/10583602