常见的HTTP客户端和代理

Question

我正在使用apache的常见httpclient库。是否可以通过代理发出HTTP请求？更具体地说，我需要使用代理列表来处理多线程POST请求（现在我正在使用单线程GET请求进行测试）。

我试着用：

        httpclient.getHostConfiguration().setProxy("67.177.104.230", 58720);

我得到了该代码的错误：

21.03.2012. 20:49:17 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: I/O exception (java.net.ConnectException) caught when processing request: Connection refused: connect
21.03.2012. 20:49:17 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: Retrying request
21.03.2012. 20:49:19 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: I/O exception (java.net.ConnectException) caught when processing request: Connection refused: connect
21.03.2012. 20:49:19 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: Retrying request
21.03.2012. 20:49:21 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: I/O exception (java.net.ConnectException) caught when processing request: Connection refused: connect
21.03.2012. 20:49:21 org.apache.commons.httpclient.HttpMethodDirector executeWithRetry
INFO: Retrying request
org.apache.commons.httpclient.ProtocolException: The server xxxxx failed to respond with a valid HTTP response
    at org.apache.commons.httpclient.HttpMethodBase.readStatusLine(HttpMethodBase.java:1846)
    at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodBase.java:1590)
    at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:995)
    at org.apache.commons.httpclient.ConnectMethod.execute(ConnectMethod.java:144)
    at org.apache.commons.httpclient.HttpMethodDirector.executeConnect(HttpMethodDirector.java:495)
    at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:390)
    at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:170)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:396)
    at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:324)
    at test.main(test.java:42)

当我删除该行时，一切都按预期正常运行。

Answer 1

对于httpclient 4.1.x，您可以像这样设置代理（取自this example）：

    HttpHost proxy = new HttpHost("127.0.0.1", 8080, "http");

    DefaultHttpClient httpclient = new DefaultHttpClient();
    try {
        httpclient.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);

        HttpHost target = new HttpHost("issues.apache.org", 443, "https");
        HttpGet req = new HttpGet("/");

        System.out.println("executing request to " + target + " via " + proxy);
        HttpResponse rsp = httpclient.execute(target, req);
        ...
    } finally {
        // When HttpClient instance is no longer needed,
        // shut down the connection manager to ensure
        // immediate deallocation of all system resources
        httpclient.getConnectionManager().shutdown();
    }

Answer 2

以下是如何使用HTTPClient的最新版本（4.3.4）

    CloseableHttpClient httpclient = HttpClients.createDefault();
    try {
        HttpHost target = new HttpHost("localhost", 443, "https");
        HttpHost proxy = new HttpHost("127.0.0.1", 8080, "http");

        RequestConfig config = RequestConfig.custom()
                .setProxy(proxy)
                .build();
        HttpGet request = new HttpGet("/");
        request.setConfig(config);

        System.out.println("Executing request " + request.getRequestLine() + " to " + target + " via " + proxy);

        CloseableHttpResponse response = httpclient.execute(target, request);
        try {
            System.out.println("----------------------------------------");
            System.out.println(response.getStatusLine());
            EntityUtils.consume(response.getEntity());
        } finally {
            response.close();
        }
    } finally {
        httpclient.close();
    }

Answer 3

从Apache HTTPComponents 4.3.x开始，HttpClientBuilder类从系统属性http.proxyHost和http.proxyPort设置代理默认值，否则您可以使用setProxy方法覆盖它们。

Answer 4

虽然这个问题很老，但我看到的还是没有确切的答案。我会在这里试着回答这个问题。

我相信这里的问题是如何设置Apache commons HttpClient（org.apache.commons.httpclient.HttpClient）的代理设置。

下面的代码段应该有效：

HttpClient client = new HttpClient();
HostConfiguration hostConfiguration = client.getHostConfiguration();
hostConfiguration.setProxy("localhost", 8080);
client.setHostConfiguration(hostConfiguration);

Answer 5

这是我如何解决旧的（<4.3）HttpClient（我无法升级）的问题，使用Santosh Singh的答案（我给了+1）：

HttpClient httpclient = new HttpClient();
if (System.getProperty("http.proxyHost") != null) {
  try {
    HostConfiguration hostConfiguration = httpclient.getHostConfiguration();
    hostConfiguration.setProxy(System.getProperty("http.proxyHost"), Integer.parseInt(System.getProperty("http.proxyPort")));
    httpclient.setHostConfiguration(hostConfiguration);
    this.getLogger().warn("USING PROXY: "+httpclient.getHostConfiguration().getProxyHost());
  } catch (Exception e) {
    throw new ProcessingException("Cannot set proxy!", e);
  }
}

Answer 6

我和HttpClient版本4有类似的问题。

由于SOCKS代理错误我无法连接到服务器，我使用以下配置修复它：

client.getParams().setParameter("socksProxyHost",proxyHost);
client.getParams().setParameter("socksProxyPort",proxyPort);

Answer 7

如果您的软件使用ProxySelector（例如使用PAC脚本而不是静态主机/端口）并且您的HTTPComponents是4.3或更高版本，那么您可以将ProxySelector用于HttpClient，如下所示：

ProxySelector myProxySelector = ...;
HttpClient myHttpClient = HttpClientBuilder.create().setRoutePlanner(new SystemDefaultRoutePlanner(myProxySelector))).build();

然后像往常一样处理您的请求：

HttpGet myRequest = new HttpGet("/");
myHttpClient.execute(myRequest);