java网络编程中常用的类
1、InetAddress
用于封装计算机的IP地址和DNS(Domain Name System域名系统)（没有端口信息）
InetAddress没有构造器，要得到对象只能通过静态方法实现
/**
* 使用getLocalHost的方法创建InetAddress对象
*/
package com.InetAddress;
import java.net.InetAddress;
public class Test1 {
public static void main(String[] args) throws Exception {
InetAddress addr = InetAddress.getLocalHost();
System.out.println("HostAddress:"+addr.getHostAddress());
System.out.println("HostName:"+addr.getHostName());
}
}
/**
* 根据域名得到InetAddress对象
*/
package com.InetAddress;
import java.net.InetAddress;
public class Test2 {
public static void main(String[] args) throws Exception {
InetAddress addr = InetAddress.getByName("www.sxt.cn");//返回sxt服务器的ip
System.out.println(addr.getHostAddress());
System.out.println(addr.getHostName());
}
}
/**
* 根据IP得到InetAddress对象
*/
package com.InetAddress;
import java.net.InetAddress;
public class Test3 {
public static void main(String[] args) throws Exception{
InetAddress addr = InetAddress.getByName("59.110.14.7");
System.out.println(addr.getHostName());
System.out.println(addr.getHostAddress());
}
}
2、InetSocketAddress
用于包含IP地址和端口信息，常用于socket编程
package com.InetSocketAddress;
import java.net.InetSocketAddress;
public class Test1 {
public static void main(String[] args) {
InetSocketAddress addr1 = new InetSocketAddress("127.0.0.1",8080);
InetSocketAddress addr2 = new InetSocketAddress("localhost",9000);
System.out.println(addr1.getHostName());
System.out.println(addr2.getAddress());
}
}
127.0.0.1
localhost/127.0.0.1
3、URL
统一资源定位符，标识计算机上的资源，是指向互联网资源的指针
资源可以是简单的文件或目录，也可以是更为复杂的对象引用，例如数据库或搜索引擎进行查询
/**
* URL类的使用
*/
package com.URL;
import java.net.URL;
public class Test1 {
public static void main(String[] args) throws Exception{
URL u = new URL("http://google.cn.80/webhp#aa?canhu=33");
System.out.println("获取与此URL关联的协议默认端口："+u.getDefaultPort());
System.out.println("port:"+u.getPort());//端口，如果是www.google.cn:80 则返回80，否则返回-1
System.out.println("file:"+u.getFile());//端口后面的内容
System.out.println("path:"+u.getPath());//路径，端口号后、参数前的内容
System.out.println("protocol:"+u.getProtocol());//协议
System.out.println("query:"+u.getQuery());//参数部分
System.out.println("host:"+u.getHost());//主机名
System.out.println("ref:"+u.getRef());//描点
URL u1 = new URL("http://www.abc.com/aa/");
URL u2 = new URL(u1,"a.html");
System.out.println(u2.toString());
}
}
获取与此URL关联的协议默认端口：80
port:-1
file:/webhp
path:/webhp
protocol:http
query:null
host:google.cn.80
ref:aa?canhu=33
http://www.abc.com/aa/a.html
4、最简单的网络爬虫
/**
* 最简单的网络爬虫
*/
package com.BasicSpider;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
public class Test1 {
public static void main(String[] args) {
URL url = null;
InputStream is = null;
BufferedReader br = null;
StringBuilder sb = new StringBuilder();
String temp = "";
try {
url = new URL("http://www.baidu.com");
is = url.openStream();
br = new BufferedReader(new InputStreamReader(is));
while((temp=br.readLine())!=null){
sb.append(temp);
}
System.out.println(sb);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally {
try {
br.close();
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
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结果：
