serialvalue.java

jsr170接口的java实现。是个apache的开源项目。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.jackrabbit.rmi.value;

import java.io.InputStream;
import java.io.Serializable;
import java.util.Calendar;

import javax.jcr.RepositoryException;
import javax.jcr.Value;
import javax.jcr.ValueFormatException;

/**
 * Stateful value implementation. This class implements the Context
 * part of the State design pattern (GoF) used for managing the JCR Value
 * states.
 * <p>
 * Instances of this class are issued by the
 * {@link org.apache.jackrabbit.rmi.value.SerialValueFactory} and are
 * <code>Serializable</code>.
 *
 * @see org.apache.jackrabbit.rmi.value.SerialValueFactory
 */
final class SerialValue implements Value, Serializable {

    /** Static serial version UID. */
    static final long serialVersionUID = 6970955308427991717L;

    /**
     * Type of the underlying value. Note that this type is never changed
     * even if the value state changes. Thus the type is memorized in this
     * member variable when the value instance is created.
     */
    private int type;

    /**
     * The underlying value instance. This is the state reference that
     * changes during state transitions.
     */
    private StatefulValue value;

    /**
     * Creates a generic value instance.  A new InitialValue instance
     * that wraps the given static value instance is created to intercept
     * the first getter method. The created InitialValue instance has
     * the responsibility of changing the value state.
     *
     * @param value underlying static value instance
     */
    SerialValue(StatefulValue value) {
        this.type = value.getType();
        this.value = new InitialValue(this, value);
    }

    /**
     * Changes the value state. This method is invoked by the
     * {@link InitialValue InitialValue} class to commit the value state.
     *
     * @param value new value state
     */
    void setValue(StatefulValue value) {
        this.value = value;
    }

    /**
     * Returns the binary representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return binary value
     * @throws IllegalStateException if the value is in non-stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getStream()
     */
    public InputStream getStream() throws IllegalStateException,
            RepositoryException {
        return value.getStream();
    }

    /**
     * Returns the string representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return string value
     * @throws ValueFormatException if conversion to string is not possible
     * @throws IllegalStateException if the value is in stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getString()
     */
    public String getString() throws ValueFormatException,
            IllegalStateException, RepositoryException {
        return value.getString();
    }

    /**
     * Returns the long representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return long value
     * @throws ValueFormatException if conversion to long is not possible
     * @throws IllegalStateException if the value is in stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getLong()
     */
    public long getLong() throws ValueFormatException,
            IllegalStateException, RepositoryException {
        return value.getLong();
    }

    /**
     * Returns the double representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return double value
     * @throws ValueFormatException if conversion to double is not possible
     * @throws IllegalStateException if the value is in stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getDouble()
     */
    public double getDouble() throws ValueFormatException,
            IllegalStateException, RepositoryException {
        return value.getDouble();
    }

    /**
     * Returns the date representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return date value
     * @throws ValueFormatException if conversion to date is not possible
     * @throws IllegalStateException if the value is in stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getDate()
     */
    public Calendar getDate() throws ValueFormatException,
            IllegalStateException, RepositoryException {
        return value.getDate();
    }

    /**
     * Returns the boolean representation of the value. The actual behaviour
     * depends on the current state of the value, see the JCR documentation
     * for the details.
     *
     * @return boolean value
     * @throws ValueFormatException if conversion to boolean is not possible
     * @throws IllegalStateException if the value is in stream state
     * @throws RepositoryException if another error occurs
     * @see Value#getDouble()
     */
    public boolean getBoolean() throws ValueFormatException,
            IllegalStateException, RepositoryException {
        return value.getBoolean();
    }

    /**
     * Returns the value type. Note that value type remains the same even
     * if the underlying value is converted to another type during the
     * stream/non-stream state transition.
     *
     * @return value type
     * @see javax.jcr.PropertyType
     * @see Value#getType()
     */
    public int getType() {
        return type;
    }
}