attribute.java

一个用于搜索本地文件内容的小型搜索引擎

    public Attribute setName(final String name) {
        final String reason  = Verifier.checkAttributeName(name);
        if (reason != null) {
            throw new IllegalNameException(name, "attribute", reason);
        }
        this.name = name;
        return this;
    }

    /**
     * This will retrieve the qualified name of the <code>Attribute</code>.
     * For any XML attribute whose name is
     * <code>[namespacePrefix]:[elementName]</code>,
     * the qualified name of the attribute would be
     * everything (both namespace prefix and
     * element name). When the attribute has no
     * namespace, the qualified name is simply the attribute's
     * local name.
     * <p>
     * To obtain the local name of the attribute, the
     * <code>{@link #getName()}</code> method should be used.
     * <p>
     * To obtain the namespace prefix for this attribute,
     * the <code>{@link #getNamespacePrefix()}</code>
     * method should be used.
     *
     * @return <code>String</code> - full name for this element.
     */
    public String getQualifiedName() {
        // Note: Any changes here should be reflected in
        // XMLOutputter.printQualifiedName()
        final String prefix = namespace.getPrefix();
        
        // no prefix found
        if ((prefix == null) || ("".equals(prefix))) {
            return getName();
        } else {
            return new StringBuffer(prefix)
                .append(':')
                .append(getName())
                .toString();
        }
    }

    /**
     * This will retrieve the namespace prefix of the
     * <code>Attribute</code>. For any XML attribute
     * which appears as
     * <code>[namespacePrefix]:[attributeName]</code>,
     * the namespace prefix of the attribute would be
     * <code>[namespacePrefix]</code>. When the attribute
     * has no namespace, an empty <code>String</code> is returned.
     *
     * @return <code>String</code> - namespace prefix of this
     *                               attribute.
     */
    public String getNamespacePrefix() {
        return namespace.getPrefix();
    }

    /**
     * This returns the URI mapped to this <code>Attribute</code>'s
     * prefix. If no mapping is found, an empty <code>String</code> is
     * returned.
     *
     * @return <code>String</code> - namespace URI for this <code>Attribute</code>.
     */
    public String getNamespaceURI() {
        return namespace.getURI();
    }

    /**
     * This will return this <code>Attribute</code>'s
     * <code>{@link Namespace}</code>.
     *
     * @return <code>Namespace</code> - Namespace object for this <code>Attribute</code>
     */
    public Namespace getNamespace() {
        return namespace;
    }

    /**
     * This sets this <code>Attribute</code>'s <code>{@link Namespace}</code>.
     * If the provided namespace is null, the attribute will have no namespace.
     * The namespace must have a prefix.
     *
     * @param namespace the new namespace
     * @return <code>Element</code> - the element modified.
     * @throws IllegalNameException if the new namespace is the default
     *         namespace. Attributes cannot be in a default namespace.
     */
    public Attribute setNamespace(Namespace namespace) {
        if (namespace == null) {
            namespace = Namespace.NO_NAMESPACE;
        }

        // Verify the attribute isn't trying to be in a default namespace
        // Attributes can't be in a default namespace
        if (namespace != Namespace.NO_NAMESPACE &&
            "".equals(namespace.getPrefix())) {
            throw new IllegalNameException("", "attribute namespace",
                "An attribute namespace without a prefix can only be the " +
                "NO_NAMESPACE namespace");
        }
        this.namespace = namespace;
        return this;
    }

    /**
     * This will return the actual textual value of this
     * <code>Attribute</code>.  This will include all text
     * within the quotation marks.
     *
     * @return <code>String</code> - value for this attribute.
     */
    public String getValue() {
        return value;
    }

    /**
     * This will set the value of the <code>Attribute</code>.
     *
     * @param value <code>String</code> value for the attribute.
     * @return <code>Attribute</code> - this Attribute modified.
     * @throws IllegalDataException if the given attribute value is
     *         illegal character data (as determined by
     *         {@link org.jdom.Verifier#checkCharacterData}).
     */
    public Attribute setValue(final String value) {
        final String reason = Verifier.checkCharacterData(value);
        if (reason != null) {
            throw new IllegalDataException(value, "attribute", reason);
        }
        this.value = value;
        return this;
    }

    /**
     * This will return the actual declared type of this
     * <code>Attribute</code>.
     *
     * @return <code>int</code> - type for this attribute.
     */
    public int getAttributeType() {
        return type;
    }

    /**
     * This will set the type of the <code>Attribute</code>.
     *
     * @param type <code>int</code> type for the attribute.
     * @return <code>Attribute</code> - this Attribute modified.
     * @throws IllegalDataException if the given attribute type is
     *         not one of the supported types.
     */
    public Attribute setAttributeType(final int type) {
        if ((type < UNDECLARED_TYPE) || (type > ENUMERATED_TYPE)) {
            throw new IllegalDataException(String.valueOf(type),
                                        "attribute", "Illegal attribute type");
        }
        this.type = type;
        return this;
    }

    /**
     * This returns a <code>String</code> representation of the
     * <code>Attribute</code>, suitable for debugging.
     *
     * @return <code>String</code> - information about the
     *         <code>Attribute</code>
     */
    public String toString() {
        return new StringBuffer()
            .append("[Attribute: ")
            .append(getQualifiedName())
            .append("=\"")
            .append(value)
            .append("\"")
            .append("]")
            .toString();
    }

    /**
     * This tests for equality of this <code>Attribute</code> to the supplied
     * <code>Object</code>.
     *
     * @param ob <code>Object</code> to compare to.
     * @return <code>boolean</code> - whether the <code>Attribute</code> is
     *         equal to the supplied <code>Object</code>.
     */
    public final boolean equals(final Object ob) {
        return (ob == this);
    }

    /**
     * This returns the hash code for this <code>Attribute</code>.
     *
     * @return <code>int</code> - hash code.
     */
    public final int hashCode() {
        return super.hashCode();
    }

    /**
     * This will return a clone of this <code>Attribute</code>.
     *
     * @return <code>Object</code> - clone of this <code>Attribute</code>.
     */
    public Object clone() {
        Attribute attribute = null;
        try {
            attribute = (Attribute) super.clone();
        }
        catch (final CloneNotSupportedException ignore) {
            // Won't happen
        }

        // Name, namespace, and value are references to imutable objects
        // and are copied by super.clone() (aka Object.clone())

        // super.clone() copies reference to set parent to null
        attribute.parent = null;
        return attribute;
    }

    /////////////////////////////////////////////////////////////////
    // Convenience Methods below here
    /////////////////////////////////////////////////////////////////

    /**
     * This gets the value of the attribute, in
     * <code>int</code> form, and if no conversion
     * can occur, throws a
     * <code>{@link DataConversionException}</code>
     *
     * @return <code>int</code> value of attribute.
     * @throws DataConversionException when conversion fails.
     */
    public int getIntValue() throws DataConversionException {
        try {
            return Integer.parseInt(value.trim());
        } catch (final NumberFormatException e) {
            throw new DataConversionException(name, "int");
        }
    }

    /**
     * This gets the value of the attribute, in
     * <code>long</code> form, and if no conversion
     * can occur, throws a
     * <code>{@link DataConversionException}</code>
     *
     * @return <code>long</code> value of attribute.
     * @throws DataConversionException when conversion fails.
     */
    public long getLongValue() throws DataConversionException {
        try {
            return Long.parseLong(value.trim());
        } catch (final NumberFormatException e) {
            throw new DataConversionException(name, "long");
        }
    }

    /**
     * This gets the value of the attribute, in
     * <code>float</code> form, and if no conversion
     * can occur, throws a
     * <code>{@link DataConversionException}</code>
     *
     * @return <code>float</code> value of attribute.
     * @throws DataConversionException when conversion fails.
     */
    public float getFloatValue() throws DataConversionException {
        try {
            // Avoid Float.parseFloat() to support JDK 1.1
            return Float.valueOf(value.trim()).floatValue();
        } catch (final NumberFormatException e) {
            throw new DataConversionException(name, "float");
        }
    }

    /**
     * This gets the value of the attribute, in
     * <code>double</code> form, and if no conversion
     * can occur, throws a
     * <code>{@link DataConversionException}</code>
     *
     * @return <code>double</code> value of attribute.
     * @throws DataConversionException when conversion fails.
     */
    public double getDoubleValue() throws DataConversionException {
        try {
            // Avoid Double.parseDouble() to support JDK 1.1
            return Double.valueOf(value.trim()).doubleValue();
        } catch (final NumberFormatException e) {
            // Specially handle INF and -INF that Double.valueOf doesn't do
            String v = value.trim();
            if ("INF".equals(v)) {
                return Double.POSITIVE_INFINITY;
            }
            if ("-INF".equals(v)) {
                return Double.NEGATIVE_INFINITY;
            }
            throw new DataConversionException(name, "double");
        }
    }

    /**
     * This gets the effective boolean value of the attribute, or throws a
     * <code>{@link DataConversionException}</code> if a conversion can't be
     * performed.  True values are: "true", "on", "1", and "yes".  False
     * values are: "false", "off", "0", and "no".  Values are trimmed before
     * comparison.  Values other than those listed here throw the exception.
     *
     * @return <code>boolean</code> value of attribute.
     * @throws DataConversionException when conversion fails.
     */
    public boolean getBooleanValue() throws DataConversionException {
        final String valueTrim = value.trim();
        if (
            (valueTrim.equalsIgnoreCase("true")) ||
            (valueTrim.equalsIgnoreCase("on")) ||
            (valueTrim.equalsIgnoreCase("1")) ||
            (valueTrim.equalsIgnoreCase("yes"))) {
            return true;
        } else if (
            (valueTrim.equalsIgnoreCase("false")) ||
            (valueTrim.equalsIgnoreCase("off")) ||
            (valueTrim.equalsIgnoreCase("0")) ||
            (valueTrim.equalsIgnoreCase("no"))
        ) {
            return false;
        } else {
            throw new DataConversionException(name, "boolean");
        }
    }

    // Support a custom Namespace serialization so no two namespace
    // object instances may exist for the same prefix/uri pair
    private void writeObject(final ObjectOutputStream out) throws IOException {

        out.defaultWriteObject();

        // We use writeObject() and not writeUTF() to minimize space
        // This allows for writing pointers to already written strings
        out.writeObject(namespace.getPrefix());
        out.writeObject(namespace.getURI());
    }

    private void readObject(final ObjectInputStream in)
        throws IOException, ClassNotFoundException {

        in.defaultReadObject();

        namespace = Namespace.getNamespace(
            (String) in.readObject(), (String) in.readObject());
    }
}