Cookie (Servlet and JavaServer Pages API Documentation)
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java.lang.Object | +--javax.servlet.http.Cookie
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
HttpServletResponse.addCookie(javax.servlet.http.Cookie)
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 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.
Constructor Summary | |
Cookie(java.lang.String name,
java.lang.String value)
Constructs a cookie with a specified name and value. |
Method Summary | |
java.lang.Object |
clone()
Overrides the standard java.lang.Object.clone
method to return a copy of this cookie. |
java.lang.String |
getComment()
Returns the comment describing the purpose of this cookie, or null if the cookie has no comment. |
java.lang.String |
getDomain()
Returns the domain name set for this cookie. |
int |
getMaxAge()
Returns the maximum age of the cookie, specified in seconds, By default, -1 indicating the cookie will persist
until browser shutdown. |
java.lang.String |
getName()
Returns the name of the cookie. |
java.lang.String |
getPath()
Returns the path on the server to which the browser returns this cookie. |
boolean |
getSecure()
Returns true if the browser is sending cookies
only over a secure protocol, or false if the
browser can send cookies using any protocol. |
java.lang.String |
getValue()
Returns the value of the cookie. |
int |
getVersion()
Returns the version of the protocol this cookie complies with. |
void |
setComment(java.lang.String purpose)
Specifies a comment that describes a cookie's purpose. |
void |
setDomain(java.lang.String pattern)
Specifies the domain within which this cookie should be presented. |
void |
setMaxAge(int expiry)
Sets the maximum age of the cookie in seconds. |
void |
setPath(java.lang.String uri)
Specifies a path for the cookie to which the client should return the cookie. |
void |
setSecure(boolean flag)
Indicates to the browser whether the cookie should only be sent using a secure protocol, such as HTTPS or SSL. |
void |
setValue(java.lang.String newValue)
Assigns a new value to a cookie after the cookie is created. |
void |
setVersion(int v)
Sets the version of the cookie protocol this cookie complies with. |
Methods inherited from class java.lang.Object |
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public Cookie(java.lang.String name, java.lang.String 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.
name
- a String
specifying the name of the cookievalue
- a String
specifying the value of the cookie
java.lang.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 protocolsetValue(java.lang.String)
,
setVersion(int)
Method Detail |
public void setComment(java.lang.String purpose)
purpose
- a String
specifying the comment
to display to the usergetComment()
public java.lang.String getComment()
null
if the cookie has no comment.
String
containing the comment,
or null
if nonesetComment(java.lang.String)
public void setDomain(java.lang.String pattern)
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.
pattern
- a String
containing the domain name
within which this cookie is visible;
form is according to RFC 2109getDomain()
public java.lang.String getDomain()
String
containing the domain namesetDomain(java.lang.String)
public void setMaxAge(int expiry)
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.
expiry
- an integer specifying the maximum age of the
cookie in seconds; if negative, means
the cookie is not stored; if zero, deletes
the cookiegetMaxAge()
public int getMaxAge()
-1
indicating the cookie will persist
until browser shutdown.
setMaxAge(int)
public void setPath(java.lang.String uri)
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.
uri
- a String
specifying a pathgetPath()
public java.lang.String getPath()
String
specifying a path that contains
a servlet name, for example, /catalogsetPath(java.lang.String)
public void setSecure(boolean flag)
The default value is false
.
flag
- if true
, sends the cookie from the browser
to the server using only when using a secure protocol;
if false
, sent on any protocolgetSecure()
public boolean getSecure()
true
if the browser is sending cookies
only over a secure protocol, or false
if the
browser can send cookies using any protocol.
true
if the browser uses a secure protocol;
otherwise, true
setSecure(boolean)
public java.lang.String getName()
String
specifying the cookie's namepublic void setValue(java.lang.String newValue)
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.
newValue
- a String
specifying the new valuegetValue()
,
Cookie
public java.lang.String getValue()
String
containing the cookie's
present valuesetValue(java.lang.String)
,
Cookie
public int getVersion()
setVersion(int)
public void setVersion(int v)
Since RFC 2109 is still somewhat new, consider version 1 as experimental; do not use it yet on production sites.
v
- 0 if the cookie should comply with
the original Netscape specification;
1 if the cookie should comply with RFC 2109getVersion()
public java.lang.Object clone()
java.lang.Object.clone
method to return a copy of this cookie.
clone
in class java.lang.Object
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