java类库详细讲解

				
				
				
				Getting the Response Headers from an HTTP Connection
				(Java Developers Almanac Example)
				
				
				
				
				
				
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				The Java Developers Almanac 1.4
				
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				    java.net
				         [27 examples]
				        
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				        HTTP
				             [4 examples]
				            
				
				  
				    e140.  
				    Getting the Response Headers from an HTTP Connection
				
				
				
				
				    try {
				        // Create a URLConnection object for a URL
				        URL url = new URL("http://hostname:80");
				        URLConnection conn = url.openConnection();
				    
				        // List all the response headers from the server.
				        // Note: The first call to getHeaderFieldKey() will implicit send
				        // the HTTP request to the server.
				        for (int i=0; ; i++) {
				            String headerName = conn.getHeaderFieldKey(i);
				            String headerValue = conn.getHeaderField(i);
				    
				            if (headerName == null && headerValue == null) {
				                // No more headers
				                break;
				            }
				            if (headerName == null) {
				                // The header value contains the server's HTTP version
				            }
				        }
				    } catch (Exception e) {
				    }
				
				Here's a sample of headers from a website:
				
				
				    Key=Value
				    
				    null=HTTP/1.1 200 OK
				    Server=Netscape-Enterprise/4.1
				    Date=Mon, 11 Feb 2002 09:23:26 GMT
				    Cache-control=public
				    Content-type=text/html
				    Etag="9fa67d2a-58-71-3bbdad3283"
				    Last-modified=Fri, 05 Oct 2001 12:53:06 GMT
				    Content-length=115
				    Accept-ranges=bytes
				    Connection=close
				
				
				
				
				             Related Examples
				        
				
				
				
				
				e141. 
				    Getting the Cookies from an HTTP Connection
				
				
				
				e142. 
				    Sending a Cookie to an HTTP Server
				
				
				
				e143. 
				    Preventing Automatic Redirects in a HTTP Connection
				
				
				
				
				
				
				
				
				        See also: 
				
				    Datagram
				  
				
				
				    Encodings
				  
				
				
				    Hostnames and IP Addresses
				  
				
				
				    Multicast
				  
				
				
				    Sockets
				  
				
				
				    URLs
				  
				
				
				
				
				
				
				
				
				
				© 2002 Addison-Wesley.