Java-网络编程 url

Java URL处理

• 基本格式

    protocol://host:port/path?query#fragment
    //协议://主机:端口/文件路径?请求参数#定位元素
  

• URL类方法--可以通过java.net.URL构建和获取资源

  1. public URL(String protocol, String host, int port, String file) throws MalformedURLException 通过给定的参数（协议、主机名、端口号、文件名）创建URL

  2. public URL(String protocol, String host, String file) throws MalformedURLException 使用指定的协议、主机名、文件名创建URL，端口使用协议的默认端口

  3. public URLConnection openConnection() throws IOException 打开一个URL连接，并运行客户端访问资源

      import java.net.*;
      import java.io.*;
     
      public class URLDemo 
      {
      	public static void main(String [] args)
      	{
      		try{
      			URL url = new URL("http:/...");
      			System.out.println("URL 为:" + url.toString());
      			System.out.println("协议为:" + url.getProtocol());
      			System.out.println("验证信息:" + url.getAuthority());
      			System.out.println("文件名及请求参数:" + url.getFile());
      			System.out.println("主机名:" + url.getHost());
      			System.out.println("路径:" + url.getPath());
      			// 还有很多。。。
      		}catch(IOException e)
      		{
      			e.printStackTrace();
      		}
      	}
      }
     

• URLConnections类方法
  openConnection()返回一个java.net.URLConnection

    import java.net.*;
    import java.io.*;
  
    public class URLConnDemo
    {
    	try
    	{
    		URL url = new URL("http://...");
    		URLConnection urlConnection = url.openConnection();
    		HttpURLConnection connection = null;
    		if(urlConnection instanceof HttpURLConnection)
    		{
    			connection = (HttpURLConnection) urlConnection;
    		}
    		else
    		{
    			System.out.println("请输入URL地址");
    			return;
    		}
    		BufferedReader in = new BufferedReader(
    		new InputStreamReader(connection.getInputStream()));
    		String urlString = "";
    		String current;
    		while((current = in.readLine()) != null)
    		{
    			urlSrtring += current;
    		}
    		System.out.println(urlString);
    	}catch(IOException e)
    	{
    		e.printStackTrace();
    	}
    }