Java之网络编程

Java之网络编程

   java 为网络支持提供了java.net包.

1. 该包下的URL和URLConnection类提供了以编程方式访问Web服务的功能

2. URLDecoder和URLEncoder提供普通字符串和application/x-www-form-urlencoded MIME

3. InetAddress类代表IP地址

程序清单:InetAddressTest.java

import java.net.InetAddress;

public class InetAddressTest {

    public static void main(String[] args) throws Exception {

        InetAddress ia = InetAddress.getByName("www.163.com");

        System.out.println("是否可到达:" + ia.isReachable(5000));

        //获取ia对象的Ip和主机名

        System.out.println(ia.getHostAddress() + "~" +ia.getHostName());

        //getCanonicalHostName返回结果是Ip地址

        System.out.println(ia.getCanonicalHostName());

        InetAddress ia1 = InetAddress.getByAddress(new byte[] {10,17,8,61});

        System.out.println("是否可到达:" + ia1.isReachable(5000));

        System.out.println(ia1.getCanonicalHostName());

    }

}

程序清单:URLDecoderTest.java

import java.net.URLDecoder;

import java.net.URLEncoder;

public class URLDecoderTest {

    public static void main(String[] args) throws Exception

    {

        //将application/x-www-form-urlencoded字符串转换成普通字符串

        //编码方式不同,结果不同

        System.out.println("utf-8:" + URLEncoder.encode("未知数据" , "utf-8"));

        System.out.println("GBK:" + URLEncoder.encode("未知数据" , "GBK"));

        //将普通字符串转换成application/x-www-form-urlencoded字符串

        System.out.println("utf-8:" + URLDecoder.decode("%E6%9C%AA%E7%9F%A5%E6%95%B0%E6%8D%AE", "utf-8"));

        System.out.println("GBK:" + URLDecoder.decode("%CE%B4%D6%AA%CA%FD%BE%DD", "GBK"));

    }

}

 

Q:上面的getCanonicalHostName()不知道有什么作用,不知道各位大虾有没有了解的?

上网google了一下,在C:\WINDOWS\system32\drivers\etc\hosts中设置了servername,就可以通过该方法获取到,否则返回IP地址.