ExternalIpAddressFetcher.java
package com.tyust.common; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.MalformedURLException; import java.net.URL; import java.util.regex.Matcher; import java.util.regex.Pattern; /** * 获取本机外网IP地址 * 思想是访问网站http://checkip.dyndns.org/，得到返回的文本后解析出本机在外网的IP地址 * @author Administrator * */ public class ExternalIpAddressFetcher { // 外网IP提供者的网址 private String externalIpProviderUrl; // 本机外网IP地址 private String myExternalIpAddress; public ExternalIpAddressFetcher(String externalIpProviderUrl) { this.externalIpProviderUrl = externalIpProviderUrl; String returnedhtml = fetchExternalIpProviderHTML(externalIpProviderUrl); parse(returnedhtml); } /** * 从外网提供者处获得包含本机外网地址的字符串 * 从http://checkip.dyndns.org返回的字符串如下 * <html><head><title>Current IP Check</title></head><body>Current IP Address: 123.147.226.222</body></html> * @param externalIpProviderUrl * @return */ private String fetchExternalIpProviderHTML(String externalIpProviderUrl) { // 输入流 InputStream in = null; // 到外网提供者的Http连接 HttpURLConnection httpConn = null; try { // 打开连接 URL url = new URL(externalIpProviderUrl); httpConn = (HttpURLConnection) url.openConnection(); // 连接设置 HttpURLConnection.setFollowRedirects(true); httpConn.setRequestMethod("GET"); httpConn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows 2000)"); // 获取连接的输入流 in = httpConn.getInputStream(); byte[] bytes=new byte[1024];// 此大小可根据实际情况调整 // 读取到数组中 int offset = 0; int numRead = 0; while (offset < bytes.length && (numRead=in.read(bytes, offset, bytes.length-offset)) >= 0) { offset += numRead; } // 将字节转化为为UTF-8的字符串 String receivedString=new String(bytes,"UTF-8"); // 返回 return receivedString; } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { in.close(); httpConn.disconnect(); } catch (Exception ex) { ex.printStackTrace(); } } // 出现异常则返回空 return null; } /** * 使用正则表达式解析返回的HTML文本,得到本机外网地址 * @param html */ private void parse(String html){ Pattern pattern=Pattern.compile("(\\d{1,3})[.](\\d{1,3})[.](\\d{1,3})[.](\\d{1,3})", Pattern.CASE_INSENSITIVE); Matcher matcher=pattern.matcher(html); while(matcher.find()){ myExternalIpAddress=matcher.group(0); } } /** * 得到本机外网地址,得不到则为空 * @return */ public String getMyExternalIpAddress() { return myExternalIpAddress; } public static void main(String[] args){ ExternalIpAddressFetcher fetcher=new ExternalIpAddressFetcher("http://checkip.dyndns.org/"); System.out.println(fetcher.getMyExternalIpAddress()); } }
也可以直接访问网站:
