java - 是否需要显式关闭 CloseableHttpClient 和 CloseableHttpResponse

Question

我有以下方法，它发出一个 HTTP POST 请求。

它返回一个CloseableHttpResponse，因此任何调用它的代码都可以获得状态代码、响应主体等。

我正在尝试理解，是否:

• CloseableHttpClient 客户端
• CloseableHttpResponse closeableHttpResponse

需要关闭吗？还是关闭一个，关闭另一个？

..
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.impl.client.CloseableHttpClient;

public static CloseableHttpResponse post(final String restEndpoint, final String data, final Header[] headers) throws Exception {
    final URIBuilder uriBuilder = new URIBuilder(restEndpoint);
    final HttpPost httpPost = new HttpPost(uriBuilder.build());
    httpPost.setHeader("Accept", "application/json");
    httpPost.setHeader("Cache-Control", "no-cache, no-store");

    if (data != null) {
        httpPost.setEntity(new StringEntity(data));
    }

    if (headers != null) {
        for (Header header : headers) {
            httpPost.setHeader(header);
        }
    }

    final CloseableHttpClient client = HttpClients.custom()
            .setSSLSocketFactory(createSSLFactory())
            .setSSLHostnameVerifier(new NoopHostnameVerifier())
            .build();

    final CloseableHttpResponse closeableHttpResponse = client.execute(httpPost);
    final int statusCode = closeableHttpResponse.getStatusLine().getStatusCode();
    logger.debug(Optional.empty(), statusCode, httpPost.toString());

    return closeableHttpResponse;
}

Answer 1

我认为 CloseableHttpResponse 需要在每个单独的请求中手动关闭。

有几种方法可以做到这一点。

使用 try/catch/finally block :

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

import java.io.IOException;

public class CloseableHttpClientWithTryCatchFinally {

    public static void main(String... args) throws Exception {

        URIBuilder uriBuilder = new URIBuilder("https://www.google.com/");

        HttpGet httpGet = new HttpGet(uriBuilder.build());

        CloseableHttpClient client = HttpClients.custom().build();

        CloseableHttpResponse response = null;

        try {
            response = client.execute(httpGet);

            response.getEntity().writeTo(System.out);

        } catch (IOException e) {

            System.out.println("Exception: " + e);
            e.printStackTrace();

        } finally {

            if (response != null) {
                response.close();
            }
        }
    }
}

我认为更好的答案是使用 try-with-resources statement :

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.utils.URIBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;

import java.io.IOException;

public class CloseableHttpClientTryWithResources {

    public static void main(String... args) throws Exception {

        URIBuilder uriBuilder = new URIBuilder("https://www.google.com/");

        HttpGet httpGet = new HttpGet(uriBuilder.build());

        CloseableHttpClient client = HttpClients.custom().build();

        try (CloseableHttpResponse response = client.execute(httpGet)) {

            response.getEntity().writeTo(System.out);

        } catch (IOException e) {

            System.out.println("Exception: " + e);
            e.printStackTrace();
        }
    }
}

一般来说，我看到人们只为他们的应用程序创建一个 CloseableHttpClient，然后在他们的应用程序中重用该实例。如果您只想一遍又一遍地使用一个或几个实例，那么不，我认为您不必关闭它们。但是，如果您要一遍又一遍地创建 CloseableHttpClient 的新实例，那么是的，您将需要关闭它们。