在Java编程中，如何查找系统的代理设置？
以下示例显示如何使用HttpURLConnection类的systemSetting()方法和getResponse()方法的put方法在系统上查找代理设置并创建代理连接。
package com.yiibai;
import java.net.HttpURLConnection; import java.net.URL; import java.util.Properties; import java.net.InetSocketAddress; import java.net.Proxy; import java.net.ProxySelector; import java.net.URI; public class FindProxySettings{ public static void main(String s[]) throws Exception { try { Properties systemSettings = System.getProperties(); systemSettings.put("proxySet", "true"); systemSettings.put("http.proxyHost", "proxy.yiibai.local"); systemSettings.put("http.proxyPort", "80"); URL u = new URL("http://www.google.com"); HttpURLConnection con = (HttpURLConnection)u.openConnection(); System.out.println(con.getResponseCode() + " : " + con.getResponseMessage()); System.out.println(con.getResponseCode() == HttpURLConnection.HTTP_OK); } catch (Exception e) { e.printStackTrace(); System.out.println(false); } System.setProperty("java.net.useSystemProxies", "true"); Proxy proxy = (Proxy) ProxySelector.getDefault().select(new URI( "http://www.baidu.com/")).iterator(). next();; System.out.println("proxy hostname : " + proxy.type()); InetSocketAddress addr = (InetSocketAddress)proxy.address(); if (addr == null) { System.out.println("No Proxy"); } else { System.out.println("proxy hostname : " + addr.getHostName()); System.out.println("proxy port : " + addr.getPort()); } } } 上述代码示例将产生以下结果 -
200 : OK
true
proxy hostname : HTTP
proxy hostname : proxy.yiibai.local
proxy port : 80
示例-2
以下是查找系统的代理设置的另一个示例：
package com.yiibai;
import java.net.InetSocketAddress; import java.net.Proxy; import java.net.ProxySelector; import java.net.URI; import java.util.Iterator; import java.util.List; public class FindProxySettings2 { public static void main(String[] args) { try { System.setProperty("java.net.useSystemProxies", "true"); List<Proxy> l = ProxySelector.getDefault().select(new URI("http://www.google.com/")); for (Iterator<Proxy> iter = l.iterator(); iter.hasNext();) { Proxy proxy = iter.next(); System.out.println("proxy hostname : " + proxy.type()); InetSocketAddress addr = (InetSocketAddress) proxy.address(); if (addr == null) { System.out.println("No Proxy"); } else { System.out.println("proxy hostname : " + addr.getHostName()); System.out.println("proxy port : " + addr.getPort()); } } } catch (Exception e) { e.printStackTrace(); } } } 上述代码示例将产生以下结果 -
proxy hostname : DIRECT
No Proxy