Cookie (Java EE 5)

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.

Author:

Various

public Cookie(String name, String value)
构造带指定名称和值的 cookie。

名称必须遵守 RFC 2109。这意味着它只能包含 ASCII 字母数字字符，不能包含逗号、分号或空格，也不能以 $ 字符开头。cookie 的名称在创建之后不得更改。

该值可以是服务器选择发送的任何值。可能只有该服务器需要其值。cookie 的值在使用 setValue 方法创建后可以更改。

默认情况下，根据 Netscape cookie 规范创建 cookie。可以使用 setVersion 方法更改版本。

name	指定 cookie 名称的 String
value	指定 cookie 值的 String
Throws	IllegalArgumentException: 如果 cookie 名称包含非法字符（例如，逗号、空格或分号），或者它是为了供 cookie 协议使用而保留的标记之一
See also	setValue, setVersion

英文文档：

Cookie

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.

Parameters:

name - a String specifying the name of the cookie

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 Also:

setValue(java.lang.String), setVersion(int)

public void setComment(String purpose)
指定一个描述 cookie 用途的注释。如果浏览器向用户显示 cookie，则注释很有用。Netscape Version 0 cookie 不支持注释。

purpose	一个 String，指定要显示给用户的注释
See also	getComment

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setComment

public void setComment(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.

Parameters:

purpose - a String specifying the comment to display to the user

See Also:

getComment()

public String getComment()
返回描述此 cookie 用途的注释；如果该 cookie 没有注释，则返回 null。

return	包含注释的 String；如果没有注释，则返回 null
See also	setComment

英文文档：

getComment

public String getComment()

Returns the comment describing the purpose of this cookie, or null if the cookie has no comment.

Returns:

a String containing the comment, or null if none

See Also:

setComment(java.lang.String)

public void setDomain(String pattern)
指定应在其中显示此 cookie 的域。

RFC 2109 指定了域名的形式。域名以点 (.foo.com) 开头，意味着在指定域名系统（Domain Name System，DNS）区域中（例如，www.foo.com，但不是 a.b.foo.com）cookie 对于服务器是可见的。默认情况下，cookie 只返回给发送它们的服务器。

pattern	包含域名（在其中此 cookie 可见）的 String；域名形式符合 RFC 2109
See also	getDomain

英文文档：

setDomain

public void setDomain(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.

Parameters:

pattern - a String containing the domain name within which this cookie is visible; form is according to RFC 2109

See Also:

getDomain()

public String getDomain()
返回为此 cookie 设置的域名。域名形式是根据 RFC 2109 设置的。

return	包含域名的 String
See also	setDomain

英文文档：

getDomain

public String getDomain()

Returns the domain name set for this cookie. The form of the domain name is set by RFC 2109.

Returns:

a String containing the domain name

See Also:

setDomain(java.lang.String)

public void setMaxAge(int expiry)
设置 cookie 的最大生存时间，以秒为单位。

正值表示 cookie 将在经过该值表示的秒数后过期。注意，该值是 cookie 过期的最大 生存时间，不是 cookie 的当前生存时间。

负值意味着 cookie 不会被持久存储，将在 Web 浏览器退出时删除。0 值会导致删除 cookie。

expiry	指定 cookie 的最大生存时间（以秒为单位）的整数；如果为负数，则表示不存储该 cookie；如果为 0，则删除该 cookie
See also	getMaxAge

英文文档：

setMaxAge

public void setMaxAge(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.

Parameters:

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 Also:

getMaxAge()

public int getMaxAge()
返回以秒为单位指定的 cookie 的最大生存时间，默认情况下，-1 指示该 cookie 将保留到浏览器关闭为止。

return	指定 cookie 的最大生存时间（以秒为单位）的整数；如果为负数，则表示该 cookie 保留到浏览器关闭为止
See also	setMaxAge

英文文档：

getMaxAge

public int getMaxAge()

Returns the maximum age of the cookie, specified in seconds, By default, -1 indicating the cookie will persist until browser shutdown.

Returns:

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

See Also:

setMaxAge(int)

public void setPath(String uri)
指定客户端应该返回 cookie 的路径。

cookie 对于指定目录中的所有页面及该目录子目录中的所有页面都是可见的。cookie 的路径必须包括设置 cookie 的 servlet，例如 /catalog，它使 cookie 对于服务器上 /catalog 下的所有目录都是可见的。

有关设置 cookie 路径名称的更多信息，请参考 RFC 2109（可从 Internet 上获得）。

uri	指定路径的 String
See also	getPath

英文文档：

setPath

public void setPath(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.

Parameters:

uri - a String specifying a path

See Also:

getPath()

public String getPath()
返回浏览器将此 cookie 返回到的服务器上的路径。cookie 对于服务器上的所有子路径都是可见的。

return	指定包含 servlet 名称的路径的 String，例如 /catalog
See also	setPath

英文文档：

getPath

public String getPath()

Returns the path on the server to which the browser returns this cookie. The cookie is visible to all subpaths on the server.

Returns:

a String specifying a path that contains a servlet name, for example, /catalog

See Also:

setPath(java.lang.String)

public void setSecure(boolean flag)
指示浏览器是否只能使用安全协议（如 HTTPS 或 SSL）发送 cookie。

默认值为 false。

flag	如果为 true，则仅在使用安全协议时将 cookie 从浏览器发送到服务器；如果为 false，则在使用任何协议时都可以发送
See also	getSecure

英文文档：

setSecure

public void setSecure(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.

Parameters:

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 Also:

getSecure()

public boolean getSecure()
如果浏览器仅通过安全协议发送 cookie，则返回 true；如果浏览器可以使用任何协议发送 cookie，则返回 false。

return	如果浏览器使用的是安全协议，则返回 true；否则返回 false
See also	setSecure

英文文档：

getSecure

public 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.

Returns:

true if the browser uses a secure protocol; otherwise, true

See Also:

setSecure(boolean)

public String getName()
返回 cookie 的名称。名称在创建之后不得更改。

return

指定 cookie 名称的 String

英文文档：

getName

public String getName()

Returns the name of the cookie. The name cannot be changed after creation.

Returns:

a String specifying the cookie's name

public void setValue(String newValue)
在创建 cookie 之后将新值分配给 cookie。如果使用二进制值，则可能需要使用 BASE64 编码。

对于 Version 0 cookie，值不应包含空格、方括号、圆括号、等号、逗号、双引号、斜杠、问号、at 符号、冒号和分号。空值在所有浏览器上的行为不一定相同。

newValue	指定新值的 String
See also	getValue, javax.servlet.http.Cookie

英文文档：

setValue

public void setValue(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.

Parameters:

newValue - a String specifying the new value

See Also:

getValue(), Cookie

public String getValue()
返回 cookie 的值。

return	包含 cookie 当前值的 String
See also	setValue, javax.servlet.http.Cookie

英文文档：

getValue

public String getValue()

Returns the value of the cookie.

Returns:

a String containing the cookie's present value

See Also:

setValue(java.lang.String), Cookie

public int getVersion()
返回此 cookie 遵守的协议版本。版本 1 遵守 RFC 2109，版本 0 遵守根据 Netscape 起草的原始 cookie 规范。浏览器提供的 cookie 使用并标识该浏览器的 cookie 版本。

return	如果 cookie 遵守原始 Netscape 规范，则返回 0；如果 cookie 遵守 RFC 2109，则返回 1
See also	setVersion

英文文档：

getVersion

public int getVersion()

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.

Returns:

0 if the cookie complies with the original Netscape specification; 1 if the cookie complies with RFC 2109

See Also:

setVersion(int)

public void setVersion(int v)
设置此 cookie 遵守的 cookie 协议版本。版本 0 遵守原始 Netscape cookie 规范。版本 1 遵守 RFC 2109。

因为 RFC 2109 仍然有点新，所以根据经验可考虑使用版本 1；但在生产网站上不要使用它。

v	如果 cookie 应该遵守原始 Netscape 规范，则该参数为 0；如果 cookie 应该遵守 RFC 2109，则该参数为 1
See also	getVersion

英文文档：

setVersion

public void setVersion(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.

Parameters:

v - 0 if the cookie should comply with the original Netscape specification; 1 if the cookie should comply with RFC 2109

See Also:

getVersion()

public Object clone()
重写标准 java.lang.Object.clone 方法以返回此 cookie 的副本。

英文文档：

clone

public Object clone()

Overrides the standard java.lang.Object.clone method to return a copy of this cookie.

Overrides:

clone in class Object

Copyright 2007 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.