java - 如何在 Java 中为 HttpClient 请求设置代理主机

Question

我想在对 URL 发送 HttpClient 请求之前设置代理。因为我能够连接它，curl 命令设置了代理，但是使用 Java 代码我无法做到这一点。

curl 命令:

**curl -I -x IP:80  URL**

在 java 文件中完成的代码更改:

HttpClient client = new HttpClient();
System.getProperties().put("http.proxyHost", "someProxyURL");
System.getProperties().put("http.proxyPort", "someProxyPort");
EntityEnclosingMethod method = new PostMethod(url);
method.setRequestEntity(new StringRequestEntity(requestXML, "text/xml", "utf-8"));

在我的 java 文件中更改了上述代码后，出现以下错误:

java.net.ConnectException: Connection refused (Connection refused)

这表明我无法将该 URL 与我尝试用于连接该 URL 的代理连接。

Answer 1

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 的完整示例，设置代理可以在下面找到

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 4.3 或 4.3+ 等其他版本，您可以查看此 SO 答案:Apache HttpClient 4.1 - Proxy Authentication