사용자가 웹브라우저에서 웹페이지를 요청하면 웹브라우저는 웹서버로 많은 정보를 전달하게 되는데 이 정보들은 모두 HTTP request 의 헤더 내에 포함되어 전달된다. HTTP Protocol 에 대한 내용은 링크를 참조하기 바란다.
아래 내용은 브라우저에서 웹서버쪽으로 보내는 정보 중에 중요한 헤더 정보를 간추린 것입니다.
Header | Description |
---|---|
Accept | This header specifies the MIME types that the browser or other clients can handle. Values of image/png or image/jpeg are the two most common possibilities. |
Accept-Charset | This header specifies the character sets the browser can use to display the information. For example ISO-8859-1. |
Accept-Encoding | This header specifies the types of encodings that the browser knows how to handle. Values of gzip or compress are the two most common possibilities. |
Accept-Language | This header specifies the client's preferred languages in case the servlet can produce results in more than one language. For example en, en-us, ru, etc. |
Authorization | This header is used by clients to identify themselves when accessing password-protected Web pages. |
Connection | This header indicates whether the client can handle persistent HTTP connections. Persistent connections permit the client or other browser to retrieve multiple files with a single request. A value of Keep-Alive means that persistent connections should be used |
Content-Length | This header is applicable only to POST requests and gives the size of the POST data in bytes. |
Cookie | This header returns cookies to servers that previously sent them to the browser. |
Host | This header specifies the host and port as given in the original URL. |
If-Modified-Since | This header indicates that the client wants the page only if it has been changed after the specified date. The server sends a code, 304 which means Not Modified header if no newer result is available. |
If-Unmodified-Since | This header is the reverse of If-Modified-Since; it specifies that the operation should succeed only if the document is older than the specified date. |
Referer | This header indicates the URL of the referring Web page. For example, if you are at Web page 1 and click on a link to Web page 2, the URL of Web page 1 is included in the Referer header when the browser requests Web page 2. |
User-Agent | This header identifies the browser or other client making the request and can be used to return different content to different types of browsers. |
HttpServletRequest 객체에서 제공하는 메소드들은 아래와 같습니다.
S.N. | Method & Description |
---|---|
1 | Cookie[] getCookies() Returns an array containing all of the Cookie objects the client sent with this request. |
2 | Enumeration getAttributeNames() Returns an Enumeration containing the names of the attributes available to this request. |
3 | Enumeration getHeaderNames() Returns an enumeration of all the header names this request contains. |
4 | Enumeration getParameterNames() Returns an Enumeration of String objects containing the names of the parameters contained in this request. |
5 | HttpSession getSession() Returns the current session associated with this request, or if the request does not have a session, creates one. |
6 | HttpSession getSession(boolean create) Returns the current HttpSession associated with this request or, if if there is no current session and create is true, returns a new session. |
7 | Locale getLocale() Returns the preferred Locale that the client will accept content in, based on the Accept-Language header |
8 | Object getAttribute(String name) Returns the value of the named attribute as an Object, or null if no attribute of the given name exists. |
9 | ServletInputStream getInputStream() Retrieves the body of the request as binary data using a ServletInputStream. |
10 | String getAuthType() Returns the name of the authentication scheme used to protect the servlet, for example, "BASIC" or "SSL," or null if the JSP was not protected |
11 | String getCharacterEncoding() Returns the name of the character encoding used in the body of this request. |
12 | String getContentType() Returns the MIME type of the body of the request, or null if the type is not known. |
13 | String getContextPath() Returns the portion of the request URI that indicates the context of the request. |
14 | String getHeader(String name) Returns the value of the specified request header as a String. |
15 | String getMethod() Returns the name of the HTTP method with which this request was made, for example, GET, POST, or PUT. |
16 | String getParameter(String name) Returns the value of a request parameter as a String, or null if the parameter does not exist. |
17 | String getPathInfo() Returns any extra path information associated with the URL the client sent when it made this request. |
18 | String getProtocol() Returns the name and version of the protocol the request. |
19 | String getQueryString() Returns the query string that is contained in the request URL after the path. |
20 | String getRemoteAddr() Returns the Internet Protocol (IP) address of the client that sent the request. |
21 | String getRemoteHost() Returns the fully qualified name of the client that sent the request. |
22 | String getRemoteUser() Returns the login of the user making this request, if the user has been authenticated, or null if the user has not been authenticated. |
23 | String getRequestURI() Returns the part of this request's URL from the protocol name up to the query string in the first line of the HTTP request. |
24 | String getRequestedSessionId() Returns the session ID specified by the client. |
25 | String getServletPath() Returns the part of this request's URL that calls the JSP. |
26 | String[] getParameterValues(String name) Returns an array of String objects containing all of the values the given request parameter has, or null if the parameter does not exist. |
27 | boolean isSecure() Returns a boolean indicating whether this request was made using a secure channel, such as HTTPS. |
28 | int getContentLength() Returns the length, in bytes, of the request body and made available by the input stream, or -1 if the length is not known. |
29 | int getIntHeader(String name) Returns the value of the specified request header as an int. |
30 | int getServerPort() Returns the port number on which this request was received. |
아래는 HttpServletRequest의 getHeaderNames()메소드 예제입니다. 이 메소드는 현재 요청에 대한 HTTP header 정보를 읽어와서 Enumeration을 반환합니다. Enumeration을 얻어오면 우리는 hasMoreElements() 메소드를 이용해서 루프를 돌면서 nextElement() 메소드를 이용해서 헤더명을 가져올 수 있습니다. 아래 예제는 그렇게 얻어온 헤더명을 이용해서 해당 헤더명에 대한 실제 값까지 얻어와서 화면에 출력하는 기능을 하는 페이지입니다.
<%@ page import="java.io.*,java.util.*" %> <html> <head> <title>HTTP Header Request Example</title> </head> <body> <center> <h2>HTTP Header Request Example</h2> <table width="100%" border="1" align="center"> <tr bgcolor="#949494"> <th>Header Name</th><th>Header Value(s)</th> </tr> <% Enumeration headerNames = request.getHeaderNames(); while(headerNames.hasMoreElements()) { String paramName = (String)headerNames.nextElement(); out.print("<tr><td>" + paramName + "</td>\n"); String paramValue = request.getHeader(paramName); out.println("<td> " + paramValue + "</td></tr>\n"); } %> </table> </center> </body> </html>
위 소스코드를 main.jsp 파일에 넣고 웹브라우저에서 요청해보세요. 아래와 같은 결과를 얻을 수 있을것입니다.
Header Name | Header Value(s) |
---|---|
accept | */* |
accept-language | en-us |
user-agent | Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; InfoPath.2; MS-RTC LM 8) |
accept-encoding | gzip, deflate |
host | localhost:8080 |
connection | Keep-Alive |
cache-control | no-cache |
Reference : http://www.tutorialspoint.com/jsp/jsp_client_request.htm
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