HttpURLConnection、HttpClient设置代理Proxy

有如下一种需求，原本A要给C发送请求，但是因为网络原因，需要借助B才能实现，所以由原本的A->C变成了A->B->C。

这种情况，更多的见于内网请求由统一的网关做代理然后转发出去，比如你本地的机器想要对外上网，都是通过运营商给的出口IP也就是公网地址实现的。这种做法就是代理了。

研究了一下针对 HttpURLConnection和HttpClient这两种常见的http请求的代理：

一、HttpURLConnection设置请求代理

贴出一个utils类

具体代码如下：

public class ProxyUtils {    public static final String CONTENT_TYPE = "application/x-www-fORM-urlencoded";    public static String getResultByHttpConnectionProxy(String url, String content, String proxyHost, int proxyPort) {        String result = "";        OutputStream outputStream = null;        InputStream inputStream = null;        try {            //设置proxy            Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyHost, proxyPort));            URL proxyUrl = new URL(url);            //判断是哪种类型的请求            if (url.startsWith("https")) {                HttpsURLConnection httpsURLConnection = (HttpsURLConnection) proxyUrl.openConnection(proxy);                httpsURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE);                //允许写入                httpsURLConnection.setDoInput(true);                //允许写出                httpsURLConnection.setDoOutput(true);                //请求方法的类型 POST/GET                httpsURLConnection.setRequestMethod("POST");                //是否使用缓存                httpsURLConnection.setUseCaches(false);                //读取超时                httpsURLConnection.setReadTimeout(15000);                //连接超时                httpsURLConnection.setConnectTimeout(15000);                //设置SSL                httpsURLConnection.setSSLSocketFactory(getSsf());                //设置主机验证程序                httpsURLConnection.setHostnameVerifier((s, sslSession) -> true);                outputStream = httpsURLConnection.getOutputStream();                outputStream.write(content.getBytes(StandardCharsets.UTF_8));                outputStream.flush();                inputStream = httpsURLConnection.getInputStream();            } else {                HttpURLConnection httpURLConnection = (HttpURLConnection) proxyUrl.openConnection(proxy);                httpURLConnection.setRequestProperty("Content-Type", CONTENT_TYPE);                httpURLConnection.setDoOutput(true);                httpURLConnection.setDoInput(true);                httpURLConnection.setRequestMethod("POST");                httpURLConnection.setUseCaches(false);                httpURLConnection.setConnectTimeout(15000);                httpURLConnection.setReadTimeout(15000);                outputStream = httpURLConnection.getOutputStream();                outputStream.write(content.getBytes("UTF-8"));                outputStream.flush();                inputStream = httpURLConnection.getInputStream();            }            byte[] bytes = read(inputStream, 1024);            result = (new String(bytes, "UTF-8")).trim();        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if (outputStream != null) {                    outputStream.close();                }                if (inputStream != null) {                    inputStream.close();                }            } catch (Exception e) {                e.printStackTrace();            }        }        return result;    }    public static byte[] read(InputStream inputStream, int bufferSize) throws IOException {        ByteArrayOutputStream baos = new ByteArrayOutputStream();        byte[] buffer = new byte[bufferSize];        for (int num = inputStream.read(buffer); num != -1; num = inputStream.read(buffer)) {            baos.write(buffer, 0, num);        }        baos.flush();        return baos.toByteArray();    }    private static SSLSocketFactory getSsf() {        SSLContext ctx = null;        try {            ctx = SSLContext.getInstance("TLS");            ctx.init(new KeyManager[0],                    new TrustManager[]{new ProxyUtils.DefaultTrustManager()},                    new SecureRandom());        } catch (Exception e) {            e.printStackTrace();        }        assert ctx != null;        return ctx.getSocketFactory();    }    private static final class DefaultTrustManager implements X509TrustManager {        @Override        public void checkClientTrusted(X509Certificate[] chain, String authType)                throws CertificateException {        }        @Override        public void checkServerTrusted(X509Certificate[] chain, String authType)                throws CertificateException {        }        @Override        public X509Certificate[] getAcceptedIssuers() {            return null;        }    }}

上面的代码就是对httpsURLConnection设置了Proxy代理，也就是请求先会发到proxyHost:proxyPort,然后由其代理发到url。

二、HttpClient设置请求代理

贴出一个utils类

具体代码如下：

public class HttpclientUtils {    private static final String CONTENT_TYPE = "application/x-www-form-urlencoded";    public static String getResultByProxy(String url, String request, String proxyHost, int proxyPort) throws Exception {        String response = null;        HttpPost httpPost = null;        try {            HttpClient httpClient = getHttpClient(url);            //设置请求配置类  重点就是在这里添加setProxy 设置代理            RequestConfig requestConfig = RequestConfig.custom().setSocketTimeout(15000).setConnectTimeout(15000)                    .setConnectionRequestTimeout(15000).setProxy(new HttpHost(proxyHost, proxyPort)).build();            httpPost = new HttpPost(url);                        httpPost.setConfig(requestConfig);            httpPost.addHeader("Content-Type", CONTENT_TYPE);            httpPost.setEntity(new StringEntity(request, "utf-8"));            response = getHttpClientResponse(httpPost, httpClient);        } catch (Exception e) {            e.printStackTrace();        } finally {            if (null != httpPost) {                httpPost.releaseConnection();            }        }        return response;    }    private static String getHttpClientResponse(HttpPost httpPost, HttpClient httpClient) throws Exception {        String result = null;        HttpResponse httpResponse = httpClient.execute(httpPost);        HttpEntity entity = httpResponse.getEntity();        if (null != entity) {            try (InputStream inputStream = entity.getContent()) {                byte[] bytes = read(inputStream, 1024);                result = new String(bytes, StandardCharsets.UTF_8);            }        }        return result;    }    private static HttpClient getHttpClient(String url) throws Exception {        HttpClient httpClient;        String lowerURL = url.toLowerCase();        if (lowerURL.startsWith("https")) {            httpClient = createSSLClientDefault();        } else {            httpClient = HttpClients.createDefault();        }        return httpClient;    }    private static CloseableHttpClient createSSLClientDefault() throws Exception {        SSLContext sslContext = new SSLContextBuilder().loadTrustMaterial(null, (chain, authType) -> true).build();        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslContext, (s, sslSession) -> true);        return HttpClients.custom().setSSLSocketFactory(sslsf).build();    }    public static byte[] read(InputStream inputStream, int bufferSize) throws IOException {        ByteArrayOutputStream baos = new ByteArrayOutputStream();        byte[] buffer = new byte[bufferSize];        for (int num = inputStream.read(buffer); num != -1; num = inputStream.read(buffer)) {            baos.write(buffer, 0, num);        }        baos.flush();        return baos.toByteArray();    }}

以上就是针对http、https的代理汇总，其实想想，就是通过 Proxy 对象，添加对应的代理地址和端口，实现了一层转发，可以想到Nginx、gateway这种思想。

欢迎大家讨论学习，本人能力有限，也是摸索探究的，有不对的地方欢迎指正。

来源地址：https://blog.csdn.net/qq_38653981/article/details/129066422