JAVA 获取指定网址的IP地址 实例

如今买票是一大难事,在高峰时段 打开12306网站,慢的像蜗牛,想到以前用修改hosts文件来登录Google(Hosts是一个没有扩展名的系统文件，可以用记事本等工具打开，其作用就是将一些常用的网址域名与其对应的IP地址建立一个关联“数据库”，当用户在浏览器中输入一个需要登录的网址时，系统会首先自动从Hosts文件中寻找对应的IP地址，一旦找到，系统会立即打开对应网页，如果没有找到，则系统再会将网址提交DNS域名解析服务器进行IP地址的解析。),那么我也来试试这种方法来登录下12306,用搜索找到几个解析IP的网站,试了下,果然奏效(现在).为了方便使用,我把IP写到本地文件.

下面是JAVA的相关代码,显示把IP写到D盘的ip.txt中.

package Demo;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class testREG_IP {

	// 指定文件路径和名称
	private static String path = "D:/ip.txt";
	private static File fileName = new File(path);
	private static String readStr = "";
	private static BufferedReader bufferReader;

	public static void main(String[] args) throws IOException {
		//网址
		String path = "http://www.17ce.com/site/http/201401_17ccef99e3d1ca9c19aea3c3d19136dc.html";
		//正则表达式,过滤IP格式
		String regex = "\\d+\\.\\d+\\.\\d+\\.\\d+";
		String ipText = getWeb(path, regex);
		createTxtFile();
		readTxtFile();
		System.out.println(ipText);
		writeTxtFile(ipText);
	}
	/**
	 * 创建文件
	 *
	 * @throws IOException
	 */
	private static void createTxtFile() throws IOException {
		if (!fileName.exists()) {
			fileName.createNewFile();
			System.err.println(fileName + " 已创建！");
		}
	}

	/**
	 * 读文件
	 */
	public static String readTxtFile() {
		String read;
		FileReader fileread;
		try {
			fileread = new FileReader(fileName);
			bufferReader = new BufferedReader(fileread);
			try {
				while ((read = bufferReader.readLine()) != null) {
					readStr = readStr + read + "\r\n";
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
		return readStr;
	}

	/**
	 * 写文件
	 */
	public static void writeTxtFile(String newStr) throws IOException {
		// 追加内容
		String filein = newStr + "\r\n" + readStr + "\r\n";
		RandomAccessFile mm = null;
		try {
			mm = new RandomAccessFile(fileName, "rw");
			mm.writeBytes(filein);
			System.out.println("写入成功");
		} catch (IOException e1) {
			System.out.println("写入失败");
			e1.printStackTrace();
		} finally {
			if (mm != null) {
				try {
					mm.close();
				} catch (IOException e2) {
					System.out.println("写入失败");
					e2.printStackTrace();
				}
			}
		}
	}
        //获取ip
	public static String getWeb(String ip, String regex) {
		URL url;
		final StringBuffer stringBuffer = new StringBuffer();
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String time = formatter.format(new Date());
		stringBuffer.append("\r\n----------" + time + "-----------\r\n\r\n\r\n");
		try {
			url = new URL(ip);
			HttpURLConnection urlConnection = (HttpURLConnection) url
					.openConnection();
			urlConnection.connect();
			InputStream in = urlConnection.getInputStream();
			byte[] data = new byte[1024];
			while (in.read(data) > 0) { // 读取流文件
				String tempString = new String(data);
				Matcher m = Pattern.compile(regex).matcher(tempString);
				while (m.find()) {
					stringBuffer.append(m.group());
					stringBuffer.append("\r\n");
				}
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		return stringBuffer.toString();
	}

}