首页 > 代码库 > Java网络编程（一）

Java网络编程（一）

2024-07-24 17:39:15 221人阅读

一、综述

【参考：http://www.cnblogs.com/oubo/archive/2012/01/16/2394641.html】

二、Java网络编程常用类

1.InteAddress类

（1）重要API：

`static InetAddress[]`	`getAllByName(String host)` Given the name of a host, returns an array of its IP addresses, based on the configured name service on the system.
`static InetAddress`	`getByAddress(byte[] addr)` Returns an `InetAddress` object given the raw IP address .
`static InetAddress`	`getByAddress(String host, byte[] addr)` Creates an InetAddress based on the provided host name and IP address.
`static InetAddress`	`getByName(String host)` Determines the IP address of a host, given the host‘s name.
`String`	`getCanonicalHostName()` Gets the fully qualified domain name for this IP address.
`String`	`getHostAddress()` Returns the IP address string in textual presentation.
`String`	`getHostName()` Gets the host name for this IP address.

`boolean`	`isReachable(int timeout)` Test whether that address is reachable.
`boolean`	`isReachable(NetworkInterface netif, int ttl, int timeout)` Test whether that address is reachable.

（2）举例

package javanet;import java.net.InetAddress;public class TestInetAddress{    public static void main(String[] args)throws Exception{        InetAddress ip=InetAddress.getByName("www.baidu.com");        System.out.println(ip.getHostAddress()+","+ip.getHostName());        System.out.println(ip.getCanonicalHostName());        System.out.println("百度是否可达：" + ip.isReachable(2000));                //返回给定服务器对应IP地址组成的数组        InetAddress[] ip2=InetAddress.getAllByName("www.baidu.com");        for(InetAddress u:ip2)            System.out.println(u.toString());                    InetAddress local = InetAddress.getByAddress(new byte[]{127,0,0,1});        System.out.println(local.getHostAddress()+","+local.getHostName());        System.out.println(local.getCanonicalHostName());        System.out.println("本机是否可达：" + local.isReachable(3000));            }}

2.URL类

（1）URL的组成

protocol://resourceName
　　协议名（protocol）指明获取资源所使用的传输协议，如http、ftp、gopher、file等，资源名（resourceName）则应该是资源的完整地址，包括主机名、端口号、文件名或文件内部的一个引用。例如：
　　http://www.sun.com/ 协议名://主机名
　　http://home.netscape.com/home/welcome.html 协议名://机器名＋文件名
　　http://www.gamelan.com:80/Gamelan/network.html#BOTTOM 协议名://机器名＋端口号＋文件名＋内部引用.

（2）重要API

补充：URL类构造方法：<1>URL(String protocol, String host, int port, String file, URLStreamHandler handler)

Creates a URL object from the specified protocol, host, port number, file, and handler.

<2>URL(URL context, String spec, URLStreamHandler handler)

Creates a URL by parsing the given spec with the specified handler within a specified context.

<3>

`URLConnection`	`openConnection()` Returns a `URLConnection` instance that represents a connection to the remote object referred to by the`URL`.
`URLConnection`	`openConnection(Proxy proxy)` Same as `openConnection()`, except that the connection will be made through the specified proxy; Protocol handlers that do not support proxing will ignore the proxy parameter and make a normal connection.

（3）举例

<1> public URL (String spec);
　　　　　通过一个表示URL地址的字符串可以构造一个URL对象。
　　　　　URL urlBase=new URL("http://www. 263.net/")
<2> public URL(URL context, String spec);
　　　　　通过基URL和相对URL构造一个URL对象。
　　　　　URL net263=new URL ("http://www.263.net/");
　　　　　URL index263=new URL(net263, "index.html")
<3> public URL(String protocol, String host, String file);
　　　　　new URL("http", "www.gamelan.com", "/pages/Gamelan.net. html");
<4> public URL(String protocol, String host, int port, String file);
　　　　　URL gamelan=new URL("http", "www.gamelan.com", 80, "Pages/Gamelan.network.html");

　　注意：类URL的构造方法都声明抛弃非运行时例外（MalformedURLException），因此生成URL对象时，我们必须要对这一例外进行处理，通常是用try-catch语句进行捕获。格式如下：

try{
　　　　　URL myURL= new URL(…)
　　}catch (MalformedURLException e){
　　…　　}

import java.net.*;import java.io.*;public class URLDemo{   public static void main(String [] args)   {      try      {         URL url = new URL("http://www.w3cschool.cc/index.html?language=cn#j2se");         System.out.println("URL is " + url.toString());         System.out.println("protocol is "                                    + url.getProtocol());         System.out.println("authority is "                                    + url.getAuthority());         System.out.println("file name is " + url.getFile());         System.out.println("host is " + url.getHost());         System.out.println("path is " + url.getPath());         System.out.println("port is " + url.getPort());         System.out.println("default port is "                                   + url.getDefaultPort());         System.out.println("query is " + url.getQuery());         System.out.println("ref is " + url.getRef());      }catch(IOException e)      {         e.printStackTrace();      }   }}

3.URLConnection类

（1）openConnection() 返回一个 java.net.URLConnection。

例如：

如果你连接HTTP协议的URL, openConnection() 方法返回 HttpURLConnection 对象。
如果你连接的URL为一个 JAR 文件, openConnection() 方法将返回 JarURLConnection 对象。

等等...

（2)重要API

（3）举例

import java.net.*;import java.io.*;public class URLConnDemo{   public static void main(String [] args)   {     //1. 向指定URL发送GET方法的请求      try      {         //创建URL对象         URL url = new URL("http://www.w3cschool.cc");         //建立URL连接         URLConnection urlConnection = url.openConnection();         HttpURLConnection connection = null;         if(urlConnection instanceof HttpURLConnection)         {            connection = (HttpURLConnection) urlConnection;         }         else         {            System.out.println("Please enter an HTTP URL.");            return;         }         //创建输入流来获取GET到的数据         BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream(),"utf-8"));         String urlString = "";         String current="";         while((current = in.readLine()) != null)         {            urlString += current;         }         //System.out.println(urlString);      }      catch(IOException e)      {         e.printStackTrace();      }            //2.向指定URL发送POST请求      try{        //创建URL对象          URL url = new URL("http://sso.jwc.whut.edu.cn/Certification//login.do");          //建立URL连接          URLConnection urlConnection2 = url.openConnection();          HttpURLConnection connection2 = null;          if(urlConnection2 instanceof HttpURLConnection)          {             connection2 = (HttpURLConnection) urlConnection2;          }          else          {             System.out.println("Please enter an HTTP URL.");             return;          }                            //发送POST请求必须设置如下两行             connection2.setDoOutput(true);             connection2.setDoInput(true);             //获取URLConnection对象对应的输出流             PrintWriter out = new PrintWriter(connection2.getOutputStream());             //发送请求参数             String postdata="http://www.mamicode.com/userName=0121201030106&password=0121201030106&type=xs&imageField.x=60&imageField.y=19";            out.print(postdata);             //flush输出流的缓冲             out.flush();           //创建输入流来获取GET到的数据          BufferedReader in = new BufferedReader(new InputStreamReader(connection2.getInputStream(),"utf-8"));          String urlString2 = "";          String current="";          while((current = in.readLine()) != null)          {             urlString2 += current;          }          System.out.println(urlString2);      }      catch(IOException e)      {          e.printStackTrace();       }   }}

4.URLEncoder类和URLDecoder类

（1）重要API

URLEncoder

`static String`	`encode(String s)` Deprecated. The resulting string may vary depending on the platform‘s default encoding. Instead, use the encode(String,String) method to specify the encoding.
`static String`	`encode(String s, String enc)` Translates a string into `application/x-www-form-urlencoded` format using a specific encoding scheme.

第二个encode方法可能会抛出UnsupportedEncodingException

URLDecoder

构造方法：URLDecoder()

`static String`	`decode(String s)` Deprecated. The resulting string may vary depending on the platform‘s default encoding. Instead, use the decode(String,String) method to specify the encoding.
`static String`	`decode(String s, String enc)` Decodes a `application/x-www-form-urlencoded` string using a specific encoding scheme.

参考：1)http://docs.oracle.com/javase/8/docs/api/

2)http://www.w3cschool.cc/java/java-url-processing.html

3)http://blog.csdn.net/chenzheng_java/article/details/6248066

Java网络编程（一）

声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉：投诉/举报工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。

联系
我们

首页 > 代码库 > Java网络编程（一）

Java网络编程（一）

看完仍有疑问？有类似问题直接问程序猿