本教程中给出了一个完整的示例：How do I setting a proxy for HttpClient?

package org.kodejava.example.commons.httpclient;

import org.apache.commons.httpclient.Credentials;
import org.apache.commons.httpclient.HostConfiguration;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpMethod;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.UsernamePasswordCredentials;
import org.apache.commons.httpclient.auth.AuthScope;
import org.apache.commons.httpclient.methods.GetMethod;

import java.io.IOException;

public class HttpGetProxy {
    private static final String PROXY_HOST = "proxy.host.com";
    private static final int PROXY_PORT = 8080;

    public static void main(String[] args) {
        HttpClient client = new HttpClient();
        HttpMethod method = new GetMethod("https://kodejava.org");

        HostConfiguration config = client.getHostConfiguration();
        config.setProxy(PROXY_HOST, PROXY_PORT);

        String username = "guest";
        String password = "s3cr3t";
        Credentials credentials = new UsernamePasswordCredentials(username, password);
        AuthScope authScope = new AuthScope(PROXY_HOST, PROXY_PORT);

        client.getState().setProxyCredentials(authScope, credentials);

        try {
            client.executeMethod(method);

            if (method.getStatusCode() == HttpStatus.SC_OK) {
                String response = method.getResponseBodyAsString();
                System.out.println("Response = " + response);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            method.releaseConnection();
        }
    }
}

为此，您需要添加一个jar文件：http://repo1.maven.org/maven2/commons-httpclient/commons-httpclient/3.1/commons-httpclient-3.1.jar

Apache HttpClient 4.1设置代理的完整示例可在下面找到

HttpHost proxy = new HttpHost("ip address",port number);
DefaultHttpClient httpclient = new DefaultHttpClient();
httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY,proxy);

HttpPost httpost = new HttpPost(url);
List<NameValuePair> nvps = new ArrayList<NameValuePair>();
nvps.add(new BasicNameValuePair("param name", param));
httpost.setEntity(new UrlEncodedFormEntity(nvps, HTTP.ISO_8859_1));
HttpResponse response = httpclient.execute(httpost);

HttpEntity entity = response.getEntity();
System.out.println("Request Handled?: " + response.getStatusLine());
InputStream in = entity.getContent();
httpclient.getConnectionManager().shutdown();

资源链接：https://stackoverflow.com/a/4957144

对于其他版本，如4.3或4.3+，您可以通过以下SO回答：Apache HttpClient 4.1 - Proxy Authentication

我想这可能会有帮助：

HttpClient client = new HttpClient();

HostConfiguration config = client.getHostConfiguration();
config.setProxy("someProxyURL", "someProxyPort");

Credentials credentials = new UsernamePasswordCredentials("username", "password");
AuthScope authScope = new AuthScope("someProxyURL", "someProxyPort");
client.getState().setProxyCredentials(authScope, credentials);

EntityEnclosingMethod method = new PostMethod(url);
method.setRequestEntity(new StringRequestEntity(requestXML, "text/xml", "utf-8"));

添加maven依赖项（4.2.X+）：

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.3</version>
    <exclusions>
        <exclusion>
            <artifactId>commons-logging</artifactId>
            <groupId>commons-logging</groupId>
        </exclusion>
    </exclusions>
</dependency>

使用HttpClientBuilder并设置标志useSystemProperties：

HttpClient client = HttpClientBuilder.create().useSystemProperties().build();

那你至少有两个选择
备选办法A：推翻论点，即

java -Djava.net.useSystemProxies=true 
     -Dhttp.proxyHost=PROXY_HOST
     -Dhttp.proxyPort=PROXY_PORT 
     -Dhttp.proxyUser=USERNAME
     -Dhttp.proxyPassword=PASSWORD
     -jar your-app.jar

选项B：设置JVM（${JAVA_HOME}/lib/net.properties）：

java.net.useSystemProxies=true
http.proxyHost=some-host
http.proxyPort=some-port

并运行应用程序

系统属性通常必须预先设置，这意味着在jvm启动时使用-Dhttp.proxyHost=some.host.com-Dhttp.proxyPort=8080，不要忘记httpsProxyHost和...端口）
或者哪个也应该在静态{}块中工作。
我个人觉得Jersey客户机实现更容易使用，如果您可以选择切换的话。

Java 17的工作原理如下：

HttpClient.newBuilder().proxy(ProxySelector.of(InetSocketAddress.createUnresolved("proxy.host.de", 3126))).build();

(3126是我代码片段中的代理端口。）