file_info.java

支持多线程的ftp下载源程序,没有用任何第三方组件

package ext.down;

import java.net.*;
import java.io.*;

public class File_info
{
	String sDown_file;

	public File_info(String s1)
	{
		sDown_file = s1;
	}

	public String get_url()
	{
		int nStart_number = sDown_file.indexOf("//");
		if (nStart_number == -1)
		{
			return "-1";// -1表明此地址不是ftp地址，不含有"//"
		}
		else
		{
			int nSecond_number = sDown_file.indexOf("/", nStart_number + 3);
			if (nSecond_number == -1)
			{
				return "-1"; // -1表明此地址不是ftp地址，不含有"/"
			}
			else
			{
				String url = sDown_file.substring(nStart_number + 2,
						nSecond_number);
				return url;
			}
		}
	}

	public String get_down_file()
	{
		int nStr_length = sDown_file.length();
		int nStart_number = sDown_file.indexOf("//");
		if (nStart_number == -1)
		{
			return "-1";// -1表明此地址不是ftp地址，不含有"//"
		}
		else
		{
			int nSecond_number = sDown_file.indexOf("/", nStart_number + 3);
			if (nSecond_number == -1)
			{
				return "-1"; // -1表明此地址不是ftp地址，不含有"/"
			}
			else
			{
				String url = sDown_file.substring(nSecond_number + 1,
						nStr_length);
				return url;
			}
		}
	}

	public String get_IP()
	{
		String url = this.get_url();
		try
		{
			String ip = InetAddress.getByName(url).toString();
			return ip;
		}
		catch (UnknownHostException e)
		{
			return "-1"; // -1表示错误的主机
		}
		catch (IOException e2)
		{
			return "-2";// -2表示错误的输入输出流
		}
	}

}