说明：

上节，实现HTTP/HTTPS代理服务器，其中Http代理就是普通代理，https代理就是隧道代理，服务端已实现，本节的目标是，Java作为客户端是如何使用普通代理及隧道代理，案例如下。

HttpURLConnection使用代理：

场景，使用HTTP代理，发起http调用。

package com.what21.netty03.demo02; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.InetSocketAddress; import java.net.Proxy; import java.net.ProxySelector; import java.net.URI; import java.net.URL; import java.util.List; public class HttpProxyClientForHttp { /** * 通过系统属性设置代理 * * @param proxyAddr * @param proxyPort */ private static void setProxy(String proxyAddr, int proxyPort) { System.setProperty("java.net.useSystemProxies", "true"); // HTTP代理 System.setProperty("http.proxyHost", proxyAddr); System.setProperty("http.proxyPort", proxyPort + ""); // HTTPS代理 System.setProperty("https.proxyHost", proxyAddr); System.setProperty("https.proxyPort", proxyPort + ""); } /** * @param uri * @return */ private static Proxy getSystemProxy(String uri) { Proxy proxy = null; try { ProxySelector ps = ProxySelector.getDefault(); List<Proxy> proxyList = ps.select(new URI(uri)); for (Proxy p : proxyList) { // System.out.println("代理类型 : " + p.type()); InetSocketAddress addr = (InetSocketAddress) p.address(); if (addr == null) { System.out.println("没有代理"); } else { proxy = p; System.out.println("代理主机 : " + addr.getHostName()); System.out.println("代理端口 : " + addr.getPort()); } } } catch (Exception e) { e.printStackTrace(); } return proxy; } /** * @param use */ private static void invoke(boolean use) { // 通过系统属性设置代理 setProxy("127.0.0.1",8888); String urlStr = ""; // 获取代理 Proxy proxy = getSystemProxy(urlStr); try { URL url = new URL(urlStr); HttpURLConnection conn = null; if (use) { // 使用代理代开资源 conn = (HttpURLConnection) url.openConnection(proxy); System.out.println("使用了代理代开资源"); } else { conn = (HttpURLConnection) url.openConnection(); } conn.setRequestProperty("Content-Type", "text/xml; charset=UTF-8"); // 超时时间 conn.setConnectTimeout(10000); InputStream is = conn.getInputStream(); BufferedReader in = new BufferedReader(new InputStreamReader(is)); StringBuffer text = new StringBuffer(); String line = null; while ((line = in.readLine()) != null) { text.append(line); } if (is != null) { is.close(); } if (conn != null) { conn.disconnect(); } // 打印内容 System.out.println(text.toString()); } catch (Exception e) { e.printStackTrace(); } } /** * @param args */ public static void main(String[] args) { invoke(false); } }

HttpsURLConnection使用代理：

场景，使用HTTPS代理，发起https调用。

package com.what21.netty03.demo02; import javax.net.ssl.HttpsURLConnection; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.net.Authenticator; import java.net.InetSocketAddress; import java.net.PasswordAuthentication; import java.net.Proxy; import java.net.URL; public class HttpProxyClientForHttps { /** * 设置代理 * * @param proxyAddr * @param proxyPort */ private static Proxy createProxy(String proxyAddr, int proxyPort) { // 设置认证 Authenticator.setDefault(new Authenticator() { protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication("username", "password" .toCharArray()); } }); // 设置HTTP代理 Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress(proxyAddr, proxyPort)); return proxy; } /** * @param use */ private static void invoke(boolean use) { String urlStr = ""; // 创建代理对象 Proxy proxy = createProxy("127.0.0.1", 8888); try { URL url = new URL(urlStr); HttpsURLConnection conn = null; if (use) { // 使用代理代开资源 conn = (HttpsURLConnection) url.openConnection(); System.out.println("使用了代理代开资源"); } else { conn = (HttpsURLConnection) url.openConnection(); } conn.setRequestProperty("Charset", "UTF-8"); conn.setRequestProperty("Content-Type", "text/xml; charset=UTF-8"); // 超时时间 conn.setConnectTimeout(10000); InputStream is = conn.getInputStream(); BufferedReader in = new BufferedReader(new InputStreamReader(is)); StringBuffer text = new StringBuffer(); String line = null; while ((line = in.readLine()) != null) { text.append(line); } if (is != null) { is.close(); } if (conn != null) { conn.disconnect(); } // 打印内容 System.out.println(text.toString()); } catch (Exception e) { e.printStackTrace(); } } /** * @param args */ public static void main(String[] args) { invoke(true); } }