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Cookie.javaAPI DocApache Tomcat 6.0.1414982Fri Jul 20 04:20:34 BST 2007javax.servlet.http

Cookie

public class Cookie extends Object implements Cloneable
Creates a cookie, a small amount of information sent by a servlet to a Web browser, saved by the browser, and later sent back to the server. A cookie's value can uniquely identify a client, so cookies are commonly used for session management.

A cookie has a name, a single value, and optional attributes such as a comment, path and domain qualifiers, a maximum age, and a version number. Some Web browsers have bugs in how they handle the optional attributes, so use them sparingly to improve the interoperability of your servlets.

The servlet sends cookies to the browser by using the {@link HttpServletResponse#addCookie} method, which adds fields to HTTP response headers to send cookies to the browser, one at a time. The browser is expected to support 20 cookies for each Web server, 300 cookies total, and may limit cookie size to 4 KB each.

The browser returns cookies to the servlet by adding fields to HTTP request headers. Cookies can be retrieved from a request by using the {@link HttpServletRequest#getCookies} method. Several cookies might have the same name but different path attributes.

Cookies affect the caching of the Web pages that use them. HTTP 1.0 does not cache pages that use cookies created with this class. This class does not support the cache control defined with HTTP 1.1.

This class supports both the Version 0 (by Netscape) and Version 1 (by RFC 2109) cookie specifications. By default, cookies are created using Version 0 to ensure the best interoperability.

author
Various
version
$Version$

Fields Summary
private static final String
LSTRING_FILE
private static ResourceBundle
lStrings
private String
name
private String
value
private String
comment
private String
domain
private int
maxAge
private String
path
private boolean
secure
private int
version
private static final String
tspecials
Constructors Summary
public Cookie(String name, String value)
Constructs a cookie with a specified name and value.

The name must conform to RFC 2109. That means it can contain only ASCII alphanumeric characters and cannot contain commas, semicolons, or white space or begin with a $ character. The cookie's name cannot be changed after creation.

The value can be anything the server chooses to send. Its value is probably of interest only to the server. The cookie's value can be changed after creation with the setValue method.

By default, cookies are created according to the Netscape cookie specification. The version can be changed with the setVersion method.

param
name a String specifying the name of the cookie
param
value a String specifying the value of the cookie
throws
IllegalArgumentException if the cookie name contains illegal characters (for example, a comma, space, or semicolon) or it is one of the tokens reserved for use by the cookie protocol
see
#setValue
see
#setVersion

	// ;Version=1 ... means RFC 2109++ style
    
    

                                                                                                             			         			         	      					      					         					            

         
	if (!isToken(name)
		|| name.equalsIgnoreCase("Comment")	// rfc2019
		|| name.equalsIgnoreCase("Discard")	// 2019++
		|| name.equalsIgnoreCase("Domain")
		|| name.equalsIgnoreCase("Expires")	// (old cookies)
		|| name.equalsIgnoreCase("Max-Age")	// rfc2019
		|| name.equalsIgnoreCase("Path")
		|| name.equalsIgnoreCase("Secure")
		|| name.equalsIgnoreCase("Version")
		|| name.startsWith("$")
	    ) {
	    String errMsg = lStrings.getString("err.cookie_name_is_token");
	    Object[] errArgs = new Object[1];
	    errArgs[0] = name;
	    errMsg = MessageFormat.format(errMsg, errArgs);
	    throw new IllegalArgumentException(errMsg);
	}

	this.name = name;
	this.value = value;
    
Methods Summary
public java.lang.Objectclone()
Overrides the standard java.lang.Object.clone method to return a copy of this cookie.

	try {
	    return super.clone();
	} catch (CloneNotSupportedException e) {
	    throw new RuntimeException(e.getMessage());
	}
    
public java.lang.StringgetComment()
Returns the comment describing the purpose of this cookie, or null if the cookie has no comment.

return
a String containing the comment, or null if none
see
#setComment

	return comment;
    
public java.lang.StringgetDomain()
Returns the domain name set for this cookie. The form of the domain name is set by RFC 2109.

return
a String containing the domain name
see
#setDomain

	return domain;
    
public intgetMaxAge()
Returns the maximum age of the cookie, specified in seconds, By default, -1 indicating the cookie will persist until browser shutdown.

return
an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie persists until browser shutdown
see
#setMaxAge

	return maxAge;
    
public java.lang.StringgetName()
Returns the name of the cookie. The name cannot be changed after creation.

return
a String specifying the cookie's name

	return name;
    
public java.lang.StringgetPath()
Returns the path on the server to which the browser returns this cookie. The cookie is visible to all subpaths on the server.

return
a String specifying a path that contains a servlet name, for example, /catalog
see
#setPath

	return path;
    
public booleangetSecure()
Returns true if the browser is sending cookies only over a secure protocol, or false if the browser can send cookies using any protocol.

return
true if the browser uses a secure protocol; otherwise, true
see
#setSecure

	return secure;
    
public java.lang.StringgetValue()
Returns the value of the cookie.

return
a String containing the cookie's present value
see
#setValue
see
Cookie

	return value;
    
public intgetVersion()
Returns the version of the protocol this cookie complies with. Version 1 complies with RFC 2109, and version 0 complies with the original cookie specification drafted by Netscape. Cookies provided by a browser use and identify the browser's cookie version.

return
0 if the cookie complies with the original Netscape specification; 1 if the cookie complies with RFC 2109
see
#setVersion

	return version;
    
private booleanisToken(java.lang.String value)

    
    
    

    /*
     * Tests a string and returns true if the string counts as a 
     * reserved token in the Java language.
     * 
     * @param value		the <code>String</code> to be tested
     *
     * @return			<code>true</code> if the <code>String</code> is
     *				a reserved token; <code>false</code>
     *				if it is not			
     */

        
	int len = value.length();

	for (int i = 0; i < len; i++) {
	    char c = value.charAt(i);

	    if (c < 0x20 || c >= 0x7f || tspecials.indexOf(c) != -1)
		return false;
	}
	return true;
    
public voidsetComment(java.lang.String purpose)
Specifies a comment that describes a cookie's purpose. The comment is useful if the browser presents the cookie to the user. Comments are not supported by Netscape Version 0 cookies.

param
purpose a String specifying the comment to display to the user
see
#getComment

	comment = purpose;
    
public voidsetDomain(java.lang.String pattern)
Specifies the domain within which this cookie should be presented.

The form of the domain name is specified by RFC 2109. A domain name begins with a dot (.foo.com) and means that the cookie is visible to servers in a specified Domain Name System (DNS) zone (for example, www.foo.com, but not a.b.foo.com). By default, cookies are only returned to the server that sent them.

param
pattern a String containing the domain name within which this cookie is visible; form is according to RFC 2109
see
#getDomain

	domain = pattern.toLowerCase();	// IE allegedly needs this
    
public voidsetMaxAge(int expiry)
Sets the maximum age of the cookie in seconds.

A positive value indicates that the cookie will expire after that many seconds have passed. Note that the value is the maximum age when the cookie will expire, not the cookie's current age.

A negative value means that the cookie is not stored persistently and will be deleted when the Web browser exits. A zero value causes the cookie to be deleted.

param
expiry an integer specifying the maximum age of the cookie in seconds; if negative, means the cookie is not stored; if zero, deletes the cookie
see
#getMaxAge

	maxAge = expiry;
    
public voidsetPath(java.lang.String uri)
Specifies a path for the cookie to which the client should return the cookie.

The cookie is visible to all the pages in the directory you specify, and all the pages in that directory's subdirectories. A cookie's path must include the servlet that set the cookie, for example, /catalog, which makes the cookie visible to all directories on the server under /catalog.

Consult RFC 2109 (available on the Internet) for more information on setting path names for cookies.

param
uri a String specifying a path
see
#getPath

	path = uri;
    
public voidsetSecure(boolean flag)
Indicates to the browser whether the cookie should only be sent using a secure protocol, such as HTTPS or SSL.

The default value is false.

param
flag if true, sends the cookie from the browser to the server only when using a secure protocol; if false, sent on any protocol
see
#getSecure

	secure = flag;
    
public voidsetValue(java.lang.String newValue)
Assigns a new value to a cookie after the cookie is created. If you use a binary value, you may want to use BASE64 encoding.

With Version 0 cookies, values should not contain white space, brackets, parentheses, equals signs, commas, double quotes, slashes, question marks, at signs, colons, and semicolons. Empty values may not behave the same way on all browsers.

param
newValue a String specifying the new value
see
#getValue
see
Cookie

	value = newValue;
    
public voidsetVersion(int v)
Sets the version of the cookie protocol this cookie complies with. Version 0 complies with the original Netscape cookie specification. Version 1 complies with RFC 2109.

Since RFC 2109 is still somewhat new, consider version 1 as experimental; do not use it yet on production sites.

param
v 0 if the cookie should comply with the original Netscape specification; 1 if the cookie should comply with RFC 2109
see
#getVersion

	version = v;