Java tutorial
/* * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved. * Copyright 2004 The Apache Software Foundation * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package javax.servlet.http; import java.io.Serializable; import java.text.MessageFormat; 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. * A cookie's value can uniquely * identify a client, so cookies are commonly used for session management. * * <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. Some Web browsers have bugs in how they handle the * optional attributes, so use them sparingly to improve the interoperability * of your servlets. * * <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. * * <p>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. * * <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 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 class Cookie implements Cloneable, Serializable { private static final long serialVersionUID = -6454587001725327448L; private static final String TSPECIALS; private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings"; private static ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE); static { if (Boolean.valueOf(System.getProperty("org.glassfish.web.rfc2109_cookie_names_enforced", "true"))) { TSPECIALS = "/()<>@,;:\\\"[]?={} \t"; } else { TSPECIALS = ",; "; } } // // The value of the cookie itself. // private String name; // NAME= ... "$Name" style is reserved private String value; // value of NAME // // Attributes encoded in the header's cookie fields. // private String comment; // ;Comment=VALUE ... describes cookie's use // ;Discard ... implied by maxAge < 0 private String domain; // ;Domain=VALUE ... domain that sees cookie private int maxAge = -1; // ;Max-Age=VALUE ... cookies auto-expire private String path; // ;Path=VALUE ... URLs that see the cookie private boolean secure; // ;Secure ... e.g. use SSL private int version = 0; // ;Version=1 ... means RFC 2109++ style private boolean isHttpOnly = false; /** * Constructs a cookie with the specified name and value. * * <p>The name must conform to RFC 2109. However, vendors may * provide a configuration option that allows cookie names conforming * to the original Netscape Cookie Specification to be accepted. * * <p>The name of a cookie cannot be changed once the cookie has * been created. * * <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. * * <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 the name of the cookie * * @param value the value of the cookie * * @throws IllegalArgumentException if the cookie name is null or * empty or contains any illegal characters (for example, a comma, * space, or semicolon) or matches a token reserved for use by the * cookie protocol * * @see #setValue * @see #setVersion */ public Cookie(String name, String value) { if (name == null || name.length() == 0) { throw new IllegalArgumentException(lStrings.getString("err.cookie_name_blank")); } 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; } /** * 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 <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 the comment of the cookie, or <code>null</code> if unspecified * * @see #setComment */ public String getComment() { return comment; } /** * * Specifies the domain within which this cookie should be presented. * * <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. * * @param domain the domain name within which this cookie is visible; * form is according to RFC 2109 * * @see #getDomain */ public void setDomain(String domain) { this.domain = domain.toLowerCase(Locale.ENGLISH); // IE allegedly needs this } /** * Gets the domain name of this Cookie. * * <p>Domain names are formatted according to RFC 2109. * * @return the domain name of this Cookie * * @see #setDomain */ public String getDomain() { return domain; } /** * Sets the maximum age in seconds for this Cookie. * * <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. * * <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. * * @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; } /** * Gets the maximum age in seconds of this Cookie. * * <p>By default, <code>-1</code> is returned, which indicates that * 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. * * <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, * <code>false</code> otherwise * * @see #setSecure */ public boolean getSecure() { return secure; } /** * Returns the name of the cookie. The name cannot be changed after * creation. * * @return the name of the cookie */ public String getName() { return name; } /** * Assigns a new value to this Cookie. * * <p>If you use a binary value, you may want to use BASE64 encoding. * * <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 the new value of the cookie * * @see #getValue */ public void setValue(String newValue) { value = newValue; } /** * Gets the current value of this Cookie. * * @return the current value of this Cookie * * @see #setValue */ 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 * * @see #setVersion */ public int getVersion() { return version; } /** * Sets the version of the cookie protocol that this Cookie complies * with. * * <p>Version 0 complies with the original Netscape cookie * specification. Version 1 complies with RFC 2109. * * <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; } /* * 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> otherwise */ private boolean isToken(String value) { 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; } /** * Overrides the standard <code>java.lang.Object.clone</code> * method to return a copy of this Cookie. */ public Object clone() { try { return super.clone(); } catch (CloneNotSupportedException e) { throw new RuntimeException(e.getMessage()); } } /** * Marks or unmarks this Cookie as <i>HttpOnly</i>. * * <p>If <tt>isHttpOnly</tt> is set to <tt>true</tt>, this cookie is * marked as <i>HttpOnly</i>, by adding the <tt>HttpOnly</tt> attribute * to it. * * <p><i>HttpOnly</i> cookies are not supposed to be exposed to * client-side scripting code, and may therefore help mitigate certain * kinds of cross-site scripting attacks. * * @param isHttpOnly true if this cookie is to be marked as * <i>HttpOnly</i>, false otherwise * * @since Servlet 3.0 */ public void setHttpOnly(boolean isHttpOnly) { this.isHttpOnly = isHttpOnly; } /** * Checks whether this Cookie has been marked as <i>HttpOnly</i>. * * @return true if this Cookie has been marked as <i>HttpOnly</i>, * false otherwise * * @since Servlet 3.0 */ public boolean isHttpOnly() { return isHttpOnly; } }