Java example source code file (Attributes.java)

This example Java source code file (Attributes.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attributes, classcastexception, content_type, hashmap, illegalargumentexception, implementation\-version, implementation_version, ioexception, name, object, sealed, string, stringbuffer, utf8, util

The Attributes.java Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.util.jar;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.Collection;
import java.util.AbstractSet;
import java.util.Iterator;
import sun.util.logging.PlatformLogger;
import java.util.Comparator;
import sun.misc.ASCIICaseInsensitiveComparator;

/**
 * The Attributes class maps Manifest attribute names to associated string
 * values. Valid attribute names are case-insensitive, are restricted to
 * the ASCII characters in the set [0-9a-zA-Z_-], and cannot exceed 70
 * characters in length. Attribute values can contain any characters and
 * will be UTF8-encoded when written to the output stream.  See the
 * <a href="../../../../technotes/guides/jar/jar.html">JAR File Specification
 * for more information about valid attribute names and values.
 *
 * @author  David Connelly
 * @see     Manifest
 * @since   1.2
 */
public class Attributes implements Map<Object,Object>, Cloneable {
    /**
     * The attribute name-value mappings.
     */
    protected Map<Object,Object> map;

    /**
     * Constructs a new, empty Attributes object with default size.
     */
    public Attributes() {
        this(11);
    }

    /**
     * Constructs a new, empty Attributes object with the specified
     * initial size.
     *
     * @param size the initial number of attributes
     */
    public Attributes(int size) {
        map = new HashMap<>(size);
    }

    /**
     * Constructs a new Attributes object with the same attribute name-value
     * mappings as in the specified Attributes.
     *
     * @param attr the specified Attributes
     */
    public Attributes(Attributes attr) {
        map = new HashMap<>(attr);
    }


    /**
     * Returns the value of the specified attribute name, or null if the
     * attribute name was not found.
     *
     * @param name the attribute name
     * @return the value of the specified attribute name, or null if
     *         not found.
     */
    public Object get(Object name) {
        return map.get(name);
    }

    /**
     * Returns the value of the specified attribute name, specified as
     * a string, or null if the attribute was not found. The attribute
     * name is case-insensitive.
     * <p>
     * This method is defined as:
     * <pre>
     *      return (String)get(new Attributes.Name((String)name));
     * </pre>
     *
     * @param name the attribute name as a string
     * @return the String value of the specified attribute name, or null if
     *         not found.
     * @throws IllegalArgumentException if the attribute name is invalid
     */
    public String getValue(String name) {
        return (String)get(new Attributes.Name(name));
    }

    /**
     * Returns the value of the specified Attributes.Name, or null if the
     * attribute was not found.
     * <p>
     * This method is defined as:
     * <pre>
     *     return (String)get(name);
     * </pre>
     *
     * @param name the Attributes.Name object
     * @return the String value of the specified Attribute.Name, or null if
     *         not found.
     */
    public String getValue(Name name) {
        return (String)get(name);
    }

    /**
     * Associates the specified value with the specified attribute name
     * (key) in this Map. If the Map previously contained a mapping for
     * the attribute name, the old value is replaced.
     *
     * @param name the attribute name
     * @param value the attribute value
     * @return the previous value of the attribute, or null if none
     * @exception ClassCastException if the name is not a Attributes.Name
     *            or the value is not a String
     */
    public Object put(Object name, Object value) {
        return map.put((Attributes.Name)name, (String)value);
    }

    /**
     * Associates the specified value with the specified attribute name,
     * specified as a String. The attributes name is case-insensitive.
     * If the Map previously contained a mapping for the attribute name,
     * the old value is replaced.
     * <p>
     * This method is defined as:
     * <pre>
     *      return (String)put(new Attributes.Name(name), value);
     * </pre>
     *
     * @param name the attribute name as a string
     * @param value the attribute value
     * @return the previous value of the attribute, or null if none
     * @exception IllegalArgumentException if the attribute name is invalid
     */
    public String putValue(String name, String value) {
        return (String)put(new Name(name), value);
    }

    /**
     * Removes the attribute with the specified name (key) from this Map.
     * Returns the previous attribute value, or null if none.
     *
     * @param name attribute name
     * @return the previous value of the attribute, or null if none
     */
    public Object remove(Object name) {
        return map.remove(name);
    }

    /**
     * Returns true if this Map maps one or more attribute names (keys)
     * to the specified value.
     *
     * @param value the attribute value
     * @return true if this Map maps one or more attribute names to
     *         the specified value
     */
    public boolean containsValue(Object value) {
        return map.containsValue(value);
    }

    /**
     * Returns true if this Map contains the specified attribute name (key).
     *
     * @param name the attribute name
     * @return true if this Map contains the specified attribute name
     */
    public boolean containsKey(Object name) {
        return map.containsKey(name);
    }

    /**
     * Copies all of the attribute name-value mappings from the specified
     * Attributes to this Map. Duplicate mappings will be replaced.
     *
     * @param attr the Attributes to be stored in this map
     * @exception ClassCastException if attr is not an Attributes
     */
    public void putAll(Map<?,?> attr) {
        // ## javac bug?
        if (!Attributes.class.isInstance(attr))
            throw new ClassCastException();
        for (Map.Entry<?,?> me : (attr).entrySet())
            put(me.getKey(), me.getValue());
    }

    /**
     * Removes all attributes from this Map.
     */
    public void clear() {
        map.clear();
    }

    /**
     * Returns the number of attributes in this Map.
     */
    public int size() {
        return map.size();
    }

    /**
     * Returns true if this Map contains no attributes.
     */
    public boolean isEmpty() {
        return map.isEmpty();
    }

    /**
     * Returns a Set view of the attribute names (keys) contained in this Map.
     */
    public Set<Object> keySet() {
        return map.keySet();
    }

    /**
     * Returns a Collection view of the attribute values contained in this Map.
     */
    public Collection<Object> values() {
        return map.values();
    }

    /**
     * Returns a Collection view of the attribute name-value mappings
     * contained in this Map.
     */
    public Set<Map.Entry entrySet() {
        return map.entrySet();
    }

    /**
     * Compares the specified Attributes object with this Map for equality.
     * Returns true if the given object is also an instance of Attributes
     * and the two Attributes objects represent the same mappings.
     *
     * @param o the Object to be compared
     * @return true if the specified Object is equal to this Map
     */
    public boolean equals(Object o) {
        return map.equals(o);
    }

    /**
     * Returns the hash code value for this Map.
     */
    public int hashCode() {
        return map.hashCode();
    }

    /**
     * Returns a copy of the Attributes, implemented as follows:
     * <pre>
     *     public Object clone() { return new Attributes(this); }
     * </pre>
     * Since the attribute names and values are themselves immutable,
     * the Attributes returned can be safely modified without affecting
     * the original.
     */
    public Object clone() {
        return new Attributes(this);
    }

    /*
     * Writes the current attributes to the specified data output stream.
     * XXX Need to handle UTF8 values and break up lines longer than 72 bytes
     */
     void write(DataOutputStream os) throws IOException {
        Iterator<Map.Entry it = entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry<Object, Object> e = it.next();
            StringBuffer buffer = new StringBuffer(
                                        ((Name)e.getKey()).toString());
            buffer.append(": ");

            String value = (String)e.getValue();
            if (value != null) {
                byte[] vb = value.getBytes("UTF8");
                value = new String(vb, 0, 0, vb.length);
            }
            buffer.append(value);

            buffer.append("\r\n");
            Manifest.make72Safe(buffer);
            os.writeBytes(buffer.toString());
        }
        os.writeBytes("\r\n");
    }

    /*
     * Writes the current attributes to the specified data output stream,
     * make sure to write out the MANIFEST_VERSION or SIGNATURE_VERSION
     * attributes first.
     *
     * XXX Need to handle UTF8 values and break up lines longer than 72 bytes
     */
    void writeMain(DataOutputStream out) throws IOException
    {
        // write out the *-Version header first, if it exists
        String vername = Name.MANIFEST_VERSION.toString();
        String version = getValue(vername);
        if (version == null) {
            vername = Name.SIGNATURE_VERSION.toString();
            version = getValue(vername);
        }

        if (version != null) {
            out.writeBytes(vername+": "+version+"\r\n");
        }

        // write out all attributes except for the version
        // we wrote out earlier
        Iterator<Map.Entry it = entrySet().iterator();
        while (it.hasNext()) {
            Map.Entry<Object, Object> e = it.next();
            String name = ((Name)e.getKey()).toString();
            if ((version != null) && ! (name.equalsIgnoreCase(vername))) {

                StringBuffer buffer = new StringBuffer(name);
                buffer.append(": ");

                String value = (String)e.getValue();
                if (value != null) {
                    byte[] vb = value.getBytes("UTF8");
                    value = new String(vb, 0, 0, vb.length);
                }
                buffer.append(value);

                buffer.append("\r\n");
                Manifest.make72Safe(buffer);
                out.writeBytes(buffer.toString());
            }
        }
        out.writeBytes("\r\n");
    }

    /*
     * Reads attributes from the specified input stream.
     * XXX Need to handle UTF8 values.
     */
    void read(Manifest.FastInputStream is, byte[] lbuf) throws IOException {
        String name = null, value = null;
        byte[] lastline = null;

        int len;
        while ((len = is.readLine(lbuf)) != -1) {
            boolean lineContinued = false;
            if (lbuf[--len] != '\n') {
                throw new IOException("line too long");
            }
            if (len > 0 && lbuf[len-1] == '\r') {
                --len;
            }
            if (len == 0) {
                break;
            }
            int i = 0;
            if (lbuf[0] == ' ') {
                // continuation of previous line
                if (name == null) {
                    throw new IOException("misplaced continuation line");
                }
                lineContinued = true;
                byte[] buf = new byte[lastline.length + len - 1];
                System.arraycopy(lastline, 0, buf, 0, lastline.length);
                System.arraycopy(lbuf, 1, buf, lastline.length, len - 1);
                if (is.peek() == ' ') {
                    lastline = buf;
                    continue;
                }
                value = new String(buf, 0, buf.length, "UTF8");
                lastline = null;
            } else {
                while (lbuf[i++] != ':') {
                    if (i >= len) {
                        throw new IOException("invalid header field");
                    }
                }
                if (lbuf[i++] != ' ') {
                    throw new IOException("invalid header field");
                }
                name = new String(lbuf, 0, 0, i - 2);
                if (is.peek() == ' ') {
                    lastline = new byte[len - i];
                    System.arraycopy(lbuf, i, lastline, 0, len - i);
                    continue;
                }
                value = new String(lbuf, i, len - i, "UTF8");
            }
            try {
                if ((putValue(name, value) != null) && (!lineContinued)) {
                    PlatformLogger.getLogger("java.util.jar").warning(
                                     "Duplicate name in Manifest: " + name
                                     + ".\n"
                                     + "Ensure that the manifest does not "
                                     + "have duplicate entries, and\n"
                                     + "that blank lines separate "
                                     + "individual sections in both your\n"
                                     + "manifest and in the META-INF/MANIFEST.MF "
                                     + "entry in the jar file.");
                }
            } catch (IllegalArgumentException e) {
                throw new IOException("invalid header field name: " + name);
            }
        }
    }

    /**
     * The Attributes.Name class represents an attribute name stored in
     * this Map. Valid attribute names are case-insensitive, are restricted
     * to the ASCII characters in the set [0-9a-zA-Z_-], and cannot exceed
     * 70 characters in length. Attribute values can contain any characters
     * and will be UTF8-encoded when written to the output stream.  See the
     * <a href="../../../../technotes/guides/jar/jar.html">JAR File Specification
     * for more information about valid attribute names and values.
     */
    public static class Name {
        private String name;
        private int hashCode = -1;

        /**
         * Constructs a new attribute name using the given string name.
         *
         * @param name the attribute string name
         * @exception IllegalArgumentException if the attribute name was
         *            invalid
         * @exception NullPointerException if the attribute name was null
         */
        public Name(String name) {
            if (name == null) {
                throw new NullPointerException("name");
            }
            if (!isValid(name)) {
                throw new IllegalArgumentException(name);
            }
            this.name = name.intern();
        }

        private static boolean isValid(String name) {
            int len = name.length();
            if (len > 70 || len == 0) {
                return false;
            }
            for (int i = 0; i < len; i++) {
                if (!isValid(name.charAt(i))) {
                    return false;
                }
            }
            return true;
        }

        private static boolean isValid(char c) {
            return isAlpha(c) || isDigit(c) || c == '_' || c == '-';
        }

        private static boolean isAlpha(char c) {
            return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
        }

        private static boolean isDigit(char c) {
            return c >= '0' && c <= '9';
        }

        /**
         * Compares this attribute name to another for equality.
         * @param o the object to compare
         * @return true if this attribute name is equal to the
         *         specified attribute object
         */
        public boolean equals(Object o) {
            if (o instanceof Name) {
                Comparator<String> c = ASCIICaseInsensitiveComparator.CASE_INSENSITIVE_ORDER;
                return c.compare(name, ((Name)o).name) == 0;
            } else {
                return false;
            }
        }

        /**
         * Computes the hash value for this attribute name.
         */
        public int hashCode() {
            if (hashCode == -1) {
                hashCode = ASCIICaseInsensitiveComparator.lowerCaseHashCode(name);
            }
            return hashCode;
        }

        /**
         * Returns the attribute name as a String.
         */
        public String toString() {
            return name;
        }

        /**
         * <code>Name object for Manifest-Version
         * manifest attribute. This attribute indicates the version number
         * of the manifest standard to which a JAR file's manifest conforms.
         * @see <a href="../../../../technotes/guides/jar/jar.html#JAR_Manifest">
         *      Manifest and Signature Specification</a>
         */
        public static final Name MANIFEST_VERSION = new Name("Manifest-Version");

        /**
         * <code>Name object for Signature-Version
         * manifest attribute used when signing JAR files.
         * @see <a href="../../../../technotes/guides/jar/jar.html#JAR_Manifest">
         *      Manifest and Signature Specification</a>
         */
        public static final Name SIGNATURE_VERSION = new Name("Signature-Version");

        /**
         * <code>Name object for Content-Type
         * manifest attribute.
         */
        public static final Name CONTENT_TYPE = new Name("Content-Type");

        /**
         * <code>Name object for Class-Path
         * manifest attribute. Bundled extensions can use this attribute
         * to find other JAR files containing needed classes.
         * @see <a href="../../../../technotes/guides/extensions/spec.html#bundled">
         *      Extensions Specification</a>
         */
        public static final Name CLASS_PATH = new Name("Class-Path");

        /**
         * <code>Name object for Main-Class manifest
         * attribute used for launching applications packaged in JAR files.
         * The <code>Main-Class attribute is used in conjunction
         * with the <code>-jar command-line option of the
         * <tt>java application launcher.
         */
        public static final Name MAIN_CLASS = new Name("Main-Class");

        /**
         * <code>Name object for Sealed manifest attribute
         * used for sealing.
         * @see <a href="../../../../technotes/guides/extensions/spec.html#sealing">
         *      Extension Sealing</a>
         */
        public static final Name SEALED = new Name("Sealed");

       /**
         * <code>Name object for Extension-List manifest attribute
         * used for declaring dependencies on installed extensions.
         * @see <a href="../../../../technotes/guides/extensions/spec.html#dependency">
         *      Installed extension dependency</a>
         */
        public static final Name EXTENSION_LIST = new Name("Extension-List");

        /**
         * <code>Name object for Extension-Name manifest attribute
         * used for declaring dependencies on installed extensions.
         * @see <a href="../../../../technotes/guides/extensions/spec.html#dependency">
         *      Installed extension dependency</a>
         */
        public static final Name EXTENSION_NAME = new Name("Extension-Name");

        /**
         * <code>Name object for Extension-Name manifest attribute
         * used for declaring dependencies on installed extensions.
         * @see <a href="../../../../technotes/guides/extensions/spec.html#dependency">
         *      Installed extension dependency</a>
         */
        public static final Name EXTENSION_INSTALLATION = new Name("Extension-Installation");

        /**
         * <code>Name object for Implementation-Title
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name IMPLEMENTATION_TITLE = new Name("Implementation-Title");

        /**
         * <code>Name object for Implementation-Version
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name IMPLEMENTATION_VERSION = new Name("Implementation-Version");

        /**
         * <code>Name object for Implementation-Vendor
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name IMPLEMENTATION_VENDOR = new Name("Implementation-Vendor");

        /**
         * <code>Name object for Implementation-Vendor-Id
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name IMPLEMENTATION_VENDOR_ID = new Name("Implementation-Vendor-Id");

       /**
         * <code>Name object for Implementation-URL
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name IMPLEMENTATION_URL = new Name("Implementation-URL");

        /**
         * <code>Name object for Specification-Title
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name SPECIFICATION_TITLE = new Name("Specification-Title");

        /**
         * <code>Name object for Specification-Version
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name SPECIFICATION_VERSION = new Name("Specification-Version");

        /**
         * <code>Name object for Specification-Vendor
         * manifest attribute used for package versioning.
         * @see <a href="../../../../technotes/guides/versioning/spec/versioning2.html#wp90779">
         *      Java Product Versioning Specification</a>
         */
        public static final Name SPECIFICATION_VENDOR = new Name("Specification-Vendor");
    }
}