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Cookie.java

/**
 *
 * Copyright 2003-2004 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.
 */

//
// This source code implements specifications defined by the Java
// Community Process. In order to remain compliant with the specification
// DO NOT add / change / or delete method signatures!
//

00024 package javax.servlet.http;

import java.text.MessageFormat;
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.
 *
 * @version $Revision: 1.8 $ $Date: 2004/09/23 08:05:29 $
 */

// XXX would implement java.io.Serializable too, but can't do that
// so long as sun.servlet.* must run on older JDK 1.02 JVMs which
// don't include that support.

00069 public class Cookie implements Cloneable {
    private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
    private static ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);

    //
    // 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


    /**
     * Constructs a cookie with a specified name and value.
     *
     * <p>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.
     *
     * <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 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
     */
00122     public Cookie(String name, String value) {
        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
     */
00156     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
     */
00169     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 pattern a <code>String</code> containing the domain name
     * within which this cookie is visible; form is according to RFC 2109
     *
     * @see #getDomain
     */
00188     public void setDomain(String pattern) {
        domain = pattern.toLowerCase(); // 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
     */
00200     public String getDomain() {
        return domain;
    }

    /**
     * Sets the maximum age of the cookie in seconds.
     *
     * <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
     */
00223     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
     */
00238     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
     */
00259     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
     */
00273     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
     */
00289     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
     */
00303     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
     */
00313     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.
     *
     * <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
     */
00332     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
     */
00345     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
     */
00361     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 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
     */
00378     public void setVersion(int v) {
        version = v;
    }

    // Note -- disabled for now to allow full Netscape compatibility
    // from RFC 2068, token special case characters
    //
    // private static final String tspecials = "()<>@,;:\\\"/[]?={} \t";

    private static final String tspecials = ",; ";

    /**
     * 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
     */
00398     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.
     */
00414     public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            throw new RuntimeException(e.getMessage());
        }
    }
}


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