package javax.servlet.http;
import java.io.Serializable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.MessageFormat;
import java.util.BitSet;
import java.util.Locale;
import java.util.ResourceBundle;
/**
* 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.
* 创建一个 cookie， servlet 发给浏览器的一个小信息，被浏览器保存。之后再发送给服务器。
*
* A cookie's value can uniquely identify a client, so cookies are commonly used for
* session management.
* 一个 cookie 的值可以单独的标记出一个客户端，所以 cookies 一般被用来 session 管理。因为
* http 是一个 stateless 的协议。
*
* <p>
* 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.
* 一个 cookie 有一个 name，一个单独的 value，还有一些可选的属性，比如 注释，路径，域标记
* 最大存活时间和一个版本号。
* document.cookie 可以得到 httponly = false 的 cookie
*
*
* Some Web browsers have bugs in how they handle the optional attributes, so
* use them sparingly to improve the interoperability of your servlets.
* 一些 web browsers 在处怎样处理可选的属性有 bugs。提高 servlets 的互操作性，请慎用。
* <p>
* 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.
* servlet 用 HttpServletResponse#addCookie 向 http 的相应头添加 field, 之后发送给浏览器.
* 浏览器支持每一个 web server 保存 20 个 cookie. 每一个 cookie 的 size 可能被限制为 4
*
* <p>
* The browser returns cookies to the servlet by adding fields to HTTP request
* headers.
* 浏览器通过向 http 请求头添加 cookies 的方式返回给服务器.
*
* 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.
* 服务器通过 HttpServletRequest#getCookies 从请求中提取 cookies.
* 一些 cookie 可能有相同的 name 但是有不同的 path attribute.
*
* <p>
* 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.
* <p>
* This class supports both the RFC 2109 and the RFC 6265 specifications.
*
* By default, cookies are created using RFC 6265.
* 默认的, cookie 生成方式采用 RFC 6265. 本质所有的 Cookie 都是按规范生成的.
*/
public class Cookie implements Cloneable, Serializable {
// 校验 Cookie name
private static final CookieNameValidator validation;
static {
boolean strictServletCompliance; // 严格的 servlet
boolean strictNaming;
boolean allowSlash;
String propStrictNaming;
String propFwdSlashIsSeparator;
if (System.getSecurityManager() == null) {
strictServletCompliance = Boolean.getBoolean(
"org.apache.catalina.STRICT_SERVLET_COMPLIANCE");
propStrictNaming = System.getProperty(
"org.apache.tomcat.util.http.ServerCookie.STRICT_NAMING");
propFwdSlashIsSeparator = System.getProperty(
"org.apache.tomcat.util.http.ServerCookie.FWD_SLASH_IS_SEPARATOR");
} else {
strictServletCompliance = AccessController.doPrivileged(
new PrivilegedAction<Boolean>() {
@Override
public Boolean run() {
return Boolean.valueOf(System.getProperty(
"org.apache.catalina.STRICT_SERVLET_COMPLIANCE"));
}
}
).booleanValue();
propStrictNaming = AccessController.doPrivileged(
new PrivilegedAction<String>() {
@Override
public String run() {
return System.getProperty(
"org.apache.tomcat.util.http.ServerCookie.STRICT_NAMING");
}
}
);
propFwdSlashIsSeparator = AccessController.doPrivileged(
new PrivilegedAction<String>() {
@Override
public String run() {
return System.getProperty(
"org.apache.tomcat.util.http.ServerCookie.FWD_SLASH_IS_SEPARATOR");
}
}
);
}
if (propStrictNaming == null) {
strictNaming = strictServletCompliance;
} else {
strictNaming = Boolean.parseBoolean(propStrictNaming);
}
if (propFwdSlashIsSeparator == null) {
allowSlash = !strictServletCompliance;
} else {
allowSlash = !Boolean.parseBoolean(propFwdSlashIsSeparator);
}
if (strictNaming) {
validation = new RFC2109Validator(allowSlash);
} else {
validation = new RFC6265Validator();
}
}
private static final long serialVersionUID = 1L;
private final String name; // cookie name 一旦创建不能被修改
private String value; // cookie value
private int version = 0; // ;Version=1 ... means RFC 2109 style
// 默认的是 RFC 6265
//
// Attributes encoded in the header's cookie fields.
//
private String comment; // ;Comment=VALUE ... describes cookie's use
private String domain; // ;Domain=VALUE ... domain that sees cookie 可以看到 cookie 的 domain
private int maxAge = -1; // ;Max-Age=VALUE ... cookies auto-expire
private String path; // ;Path=VALUE ... URLs that see the cookie 可以看到 cookie 的 urls
private boolean secure; // ;Secure ... e.g. use SSL 启用 ssl
private boolean httpOnly; // Not in cookie specs, but supported by browsers 不在 cookie 规范里, 但是被浏览器支持
/**
* Constructs a cookie with a specified name and value.
* <p>
* The name must conform to RFC 2109. cookie name 必须遵循 RFC 2109. 没办法,规范就是牛啊
* 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.
* 这意味着 cookie name 只能包含 ASCII 的字母, 数字, 不能包括逗号, 分号, 空格, 或者以
* $ 开头. cookie name 一旦创建不能被修改.
*
* <p>
* 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 <code>setValue</code> method.
* server 可以通过 cookie value 发送任何东西.
* <p>
* By default, cookies are created according to the Netscape cookie
* specification. The version can be changed with the
* <code>setVersion</code> method.
*
* @param name
* a <code>String</code> specifying the name of the cookie
* @param value
* a <code>String</code> 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
*/
public Cookie(String name, String value) {
// 首先进行 cookie name 的校验
validation.validate(name);
this.name = name;
this.value = value;
}
/**
* Specifies a comment that describes a cookie's purpose.
* 描述这个 cookie 的目的
* 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 <code>String</code> specifying the comment to display to the
* user
* @see #getComment
*/
public void setComment(String purpose) {
comment = purpose;
}
/**
* Returns the comment describing the purpose of this cookie, or
* <code>null</code> if the cookie has no comment.
*
* @return a <code>String</code> containing the comment, or
* <code>null</code> if none
* @see #setComment
*/
public String getComment() {
return comment;
}
/**
* Specifies the domain within which this cookie should be presented.
* 指定这个 cookie 可以出现在那个 domain
* <p>
* The form of the domain name is specified by RFC 2109. A domain name
* begins with a dot (<code>.foo.com</code>) and means that the cookie is
* visible to servers in a specified Domain Name System (DNS) zone (for
* example, <code>www.foo.com</code>, but not <code>a.b.foo.com</code>). By
* default, cookies are only returned to the server that sent them.
*
* domain name 的形式说明在 RFC 2109. domain name 以 dot 开头, 这意味着在一个特定的
* DNS 这个 cookie 是可见的. 默认的, 那个服务器发送的 cookie 返回给哪个服务器.
*
* @param pattern
* a <code>String</code> containing the domain name within which
* this cookie is visible; form is according to RFC 2109
* @see #getDomain
*/
public void setDomain(String pattern) {
domain = pattern.toLowerCase(Locale.ENGLISH); // IE allegedly needs this
}
/**
* Returns the domain name set for this cookie. The form of the domain name
* is set by RFC 2109.
*
* @return a <code>String</code> containing the domain name
* @see #setDomain
*/
public String getDomain() {
return domain;
}
/**
* Sets the maximum age of the cookie in seconds.
* cookie 最大存活的秒数
* <p>
* A positive value indicates that the cookie will expire after that many
* seconds have passed. Note that the value is the <i>maximum</i> age when
* the cookie will expire, not the cookie's current age.
* 一个正数表明 cookie 将在 maximun age 秒数后过期.
* <p>
* 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.
*
* 一个负数表示 cookie 不会被永久存储, 浏览器退出时将被删除.
* 0 删除这个 cookie
*
* @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
*/
public void setMaxAge(int expiry) {
maxAge = expiry;
}
/**
* Returns the maximum age of the cookie, specified in seconds, By default,
* <code>-1</code> 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
*/
public int getMaxAge() {
return maxAge;
}
/**
* Specifies a path for the cookie to which the client should return the
* cookie.
* 指定一个 path, 表示哪一个 client 应该把这个 cookie 返还给服务器.
*
* <p>
* 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, <i>/catalog</i>,
* which makes the cookie visible to all directories on the server under
* <i>/catalog</i>.
* <p>
* Consult RFC 2109 (available on the Internet) for more information on
* setting path names for cookies.
*
* @param uri
* a <code>String</code> specifying a path
* @see #getPath
*/
public void setPath(String uri) {
path = uri;
}
/**
* 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 <code>String</code> specifying a path that contains a servlet
* name, for example, <i>/catalog</i>
* @see #setPath
*/
public String getPath() {
return path;
}
/**
* Indicates to the browser whether the cookie should only be sent using a
* secure protocol, such as HTTPS or SSL.
* <p>
* The default value is <code>false</code>.
*
* @param flag
* if <code>true</code>, sends the cookie from the browser to the
* server only when using a secure protocol; if
* <code>false</code>, sent on any protocol
* @see #getSecure
*/
public void setSecure(boolean flag) {
secure = flag;
}
/**
* Returns <code>true</code> if the browser is sending cookies only over a
* secure protocol, or <code>false</code> if the browser can send cookies
* using any protocol.
*
* @return <code>true</code> if the browser uses a secure protocol;
* otherwise, <code>true</code>
* @see #setSecure
*/
public boolean getSecure() {
return secure;
}
/**
* Returns the name of the cookie. The name cannot be changed after
* creation.
*
* @return a <code>String</code> specifying the cookie's name
*/
public String getName() {
return name;
}
/**
* 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.
* cookie 被创建后, 给 value 指定一个值. 如果使用二进制的值, 采用 BASE64 的编码方式.
*
* <p>
* 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 <code>String</code> specifying the new value
* @see #getValue
* @see Cookie
*/
public void setValue(String newValue) {
value = newValue;
}
/**
* Returns the value of the cookie.
*
* @return a <code>String</code> containing the cookie's present value
* @see #setValue
* @see Cookie
*/
public String getValue() {
return value;
}
/**
* 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 被 RFC 6265 淘汰
* @see #setVersion
*/
public int getVersion() {
return version;
}
/**
* Sets the version of the cookie protocol this cookie complies with.
* Version 0 complies with the original Netscape cookie specification.
* version 0 遵守原始的 netscape cookie 说明
* Version 1 complies with RFC 2109.
* version 1 遵守 RFC 2109 规范
* <p>
* 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
*/
public void setVersion(int v) {
version = v;
}
/**
* Overrides the standard <code>java.lang.Object.clone</code> method to
* return a copy of this cookie.
*/
@Override
public Object clone() {
try {
return super.clone();
} catch (CloneNotSupportedException e) {
throw new RuntimeException(e);
}
}
/**
* Sets the flag that controls if this cookie will be hidden from scripts on
* the client side.
*
* true 不能被 js document.cookie 操作
*
* @param httpOnly The new value of the flag
*
* @since Servlet 3.0
*/
public void setHttpOnly(boolean httpOnly) {
this.httpOnly = httpOnly;
}
/**
* Gets the flag that controls if this cookie will be hidden from scripts on
* the client side.
*
* @return <code>true</code> if the cookie is hidden from scripts, else
* <code>false</code>
* @since Servlet 3.0
*/
public boolean isHttpOnly() {
return httpOnly;
}
}
class CookieNameValidator {
// 拿到 properties 文件的方法 ResourceBundle
private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
protected static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);
protected final BitSet allowed;
protected CookieNameValidator(String separators) {
allowed = new BitSet(128);
allowed.set(0x20, 0x7f); // any CHAR except CTLs or separators
for (int i = 0; i < separators.length(); i++) {
char ch = separators.charAt(i);
allowed.clear(ch);
}
}
void validate(String name) {
// cookie name 不允许为 null 或者长度为 0
if (name == null || name.length() == 0) {
throw new IllegalArgumentException(lStrings.getString("err.cookie_name_blank"));
}
if (!isToken(name)) {
String errMsg = lStrings.getString("err.cookie_name_is_token");
throw new IllegalArgumentException(MessageFormat.format(errMsg, name));
}
}
private boolean isToken(String possibleToken) {
int len = possibleToken.length();
for (int i = 0; i < len; i++) {
char c = possibleToken.charAt(i);
if (!allowed.get(c)) {
return false;
}
}
return true;
}
}
class RFC6265Validator extends CookieNameValidator {
private static final String RFC2616_SEPARATORS = "()<>@,;:\\\"/[]?={} \t";
RFC6265Validator() {
super(RFC2616_SEPARATORS);
}
}
class RFC2109Validator extends RFC6265Validator {
RFC2109Validator(boolean allowSlash) {
// special treatment to allow for FWD_SLASH_IS_SEPARATOR property
if (allowSlash) {
allowed.set('/');
}
}
@Override
void validate(String name) {
super.validate(name);
// cookie name 不允许 $ 开头
if (name.charAt(0) == '$') {
String errMsg = lStrings.getString("err.cookie_name_is_token");
throw new IllegalArgumentException(MessageFormat.format(errMsg, name));
}
}
}