src/java.sql.rowset/share/classes/javax/sql/rowset/serial/SerialArray.java - master - githubmirror/jdk17u-dev

src/java.sql.rowset/share/classes/javax/sql/rowset/serial/SerialArray.java
668 строк28 KB
Lance Andersen
8251208: Add missing javadoc comments to java.sql and java.sql.rowsets
20 авг 2020, 19:38
20 авг 2020, 19:386160353
/*
 * Copyright (c) 2003, 2020, 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 javax.sql.rowset.serial;

import java.sql.*;
import java.io.*;
import java.util.Map;
import java.net.URL;
import java.util.Arrays;


/**
 * A serialized version of an <code>Array</code>
 * object, which is the mapping in the Java programming language of an SQL
 * <code>ARRAY</code> value.
 * <P>
 * The <code>SerialArray</code> class provides a constructor for creating
 * a <code>SerialArray</code> instance from an <code>Array</code> object,
 * methods for getting the base type and the SQL name for the base type, and
 * methods for copying all or part of a <code>SerialArray</code> object.
 * <P>
 *
 * Note: In order for this class to function correctly, a connection to the
 * data source
 * must be available in order for the SQL <code>Array</code> object to be
 * materialized (have all of its elements brought to the client server)
 * if necessary. At this time, logical pointers to the data in the data source,
 * such as locators, are not currently supported.
 *
 * <h2> Thread safety </h2>
 *
 * A SerialArray is not safe for use by multiple concurrent threads.  If a
 * SerialArray is to be used by more than one thread then access to the
 * SerialArray should be controlled by appropriate synchronization.
 *
 * @since 1.5
 */
public class SerialArray implements Array, Serializable, Cloneable {

    /**
     * A serialized array in which each element is an <code>Object</code>
     * in the Java programming language that represents an element
     * in the SQL <code>ARRAY</code> value.
     * @serial
     */
    @SuppressWarnings("serial") // Not statically typed as Serializable
    private Object[] elements;

    /**
     * The SQL type of the elements in this <code>SerialArray</code> object.  The
     * type is expressed as one of the constants from the class
     * <code>java.sql.Types</code>.
     * @serial
     */
    private int baseType;

    /**
     * The type name used by the DBMS for the elements in the SQL <code>ARRAY</code>
     * value that this <code>SerialArray</code> object represents.
     * @serial
     */
    private String baseTypeName;

    /**
     * The number of elements in this <code>SerialArray</code> object, which
     * is also the number of elements in the SQL <code>ARRAY</code> value
     * that this <code>SerialArray</code> object represents.
     * @serial
     */
    private int len;

    /**
     * Constructs a new <code>SerialArray</code> object from the given
     * <code>Array</code> object, using the given type map for the custom
     * mapping of each element when the elements are SQL UDTs.
     * <P>
     * This method does custom mapping if the array elements are a UDT
     * and the given type map has an entry for that UDT.
     * Custom mapping is recursive,
     * meaning that if, for instance, an element of an SQL structured type
     * is an SQL structured type that itself has an element that is an SQL
     * structured type, each structured type that has a custom mapping will be
     * mapped according to the given type map.
     * <P>
     * The new <code>SerialArray</code>
     * object contains the same elements as the <code>Array</code> object
     * from which it is built, except when the base type is the SQL type
     * <code>STRUCT</code>, <code>ARRAY</code>, <code>BLOB</code>,
     * <code>CLOB</code>, <code>DATALINK</code> or <code>JAVA_OBJECT</code>.
     * In this case, each element in the new
     * <code>SerialArray</code> object is the appropriate serialized form,
     * that is, a <code>SerialStruct</code>, <code>SerialArray</code>,
     * <code>SerialBlob</code>, <code>SerialClob</code>,
     * <code>SerialDatalink</code>, or <code>SerialJavaObject</code> object.
     * <P>
     * Note: (1) The <code>Array</code> object from which a <code>SerialArray</code>
     * object is created must have materialized the SQL <code>ARRAY</code> value's
     * data on the client before it is passed to the constructor.  Otherwise,
     * the new <code>SerialArray</code> object will contain no data.
     * <p>
     * Note: (2) If the <code>Array</code> contains <code>java.sql.Types.JAVA_OBJECT</code>
     * types, the <code>SerialJavaObject</code> constructor is called where checks
     * are made to ensure this object is serializable.
     * <p>
     * Note: (3) The <code>Array</code> object supplied to this constructor cannot
     * return <code>null</code> for any <code>Array.getArray()</code> methods.
     * <code>SerialArray</code> cannot serialize null array values.
     *
     *
     * @param array the <code>Array</code> object to be serialized
     * @param map a <code>java.util.Map</code> object in which
     *        each entry consists of 1) a <code>String</code> object
     *        giving the fully qualified name of a UDT (an SQL structured type or
     *        distinct type) and 2) the
     *        <code>Class</code> object for the <code>SQLData</code> implementation
     *        that defines how the UDT is to be mapped. The <i>map</i>
     *        parameter does not have any effect for <code>Blob</code>,
     *        <code>Clob</code>, <code>DATALINK</code>, or
     *        <code>JAVA_OBJECT</code> types.
     * @throws SerialException if an error occurs serializing the
     *        <code>Array</code> object
     * @throws SQLException if a database access error occurs or if the
     *        <i>array</i> or the <i>map</i> values are <code>null</code>
     */
     public SerialArray(Array array, Map<String,Class<?>> map)
         throws SerialException, SQLException
     {

        if ((array == null) || (map == null)) {
            throw new SQLException("Cannot instantiate a SerialArray " +
            "object with null parameters");
        }

        if ((elements = (Object[])array.getArray()) == null) {
             throw new SQLException("Invalid Array object. Calls to Array.getArray() " +
                 "return null value which cannot be serialized");
         }

        elements = (Object[])array.getArray(map);
        baseType = array.getBaseType();
        baseTypeName = array.getBaseTypeName();
        len = elements.length;

        switch (baseType) {
            case java.sql.Types.STRUCT:
                for (int i = 0; i < len; i++) {
                    elements[i] = new SerialStruct((Struct)elements[i], map);
                }
            break;

            case java.sql.Types.ARRAY:
                for (int i = 0; i < len; i++) {
                    elements[i] = new SerialArray((Array)elements[i], map);
                }
            break;

            case java.sql.Types.BLOB:
            for (int i = 0; i < len; i++) {
                elements[i] = new SerialBlob((Blob)elements[i]);
            }
            break;

            case java.sql.Types.CLOB:
                for (int i = 0; i < len; i++) {
                    elements[i] = new SerialClob((Clob)elements[i]);
                }
            break;

            case java.sql.Types.DATALINK:
                for (int i = 0; i < len; i++) {
                    elements[i] = new SerialDatalink((URL)elements[i]);
                }
            break;

            case java.sql.Types.JAVA_OBJECT:
                for (int i = 0; i < len; i++) {
                elements[i] = new SerialJavaObject(elements[i]);
            }
        }
  }

    /**
     * This method frees the {@code SerialArray} object and releases the
     * resources that it holds. The object is invalid once the {@code free}
     * method is called. <p> If {@code free} is called multiple times, the
     * subsequent calls to {@code free} are treated as a no-op. </P>
     *
     * @throws SQLException if an error occurs releasing the SerialArray's resources
     * @since 1.6
     */
    public void free() throws SQLException {
        if (elements != null) {
            elements = null;
            baseTypeName= null;
        }
    }

    /**
     * Constructs a new <code>SerialArray</code> object from the given
     * <code>Array</code> object.
     * <P>
     * This constructor does not do custom mapping.  If the base type of the array
     * is an SQL structured type and custom mapping is desired, the constructor
     * <code>SerialArray(Array array, Map map)</code> should be used.
     * <P>
     * The new <code>SerialArray</code>
     * object contains the same elements as the <code>Array</code> object
     * from which it is built, except when the base type is the SQL type
     * <code>BLOB</code>,
     * <code>CLOB</code>, <code>DATALINK</code> or <code>JAVA_OBJECT</code>.
     * In this case, each element in the new
     * <code>SerialArray</code> object is the appropriate serialized form,
     * that is, a <code>SerialBlob</code>, <code>SerialClob</code>,
     * <code>SerialDatalink</code>, or <code>SerialJavaObject</code> object.
     * <P>
     * Note: (1) The <code>Array</code> object from which a <code>SerialArray</code>
     * object is created must have materialized the SQL <code>ARRAY</code> value's
     * data on the client before it is passed to the constructor.  Otherwise,
     * the new <code>SerialArray</code> object will contain no data.
     * <p>
     * Note: (2) The <code>Array</code> object supplied to this constructor cannot
     * return <code>null</code> for any <code>Array.getArray()</code> methods.
     * <code>SerialArray</code> cannot serialize <code>null</code> array values.
     *
     * @param array the <code>Array</code> object to be serialized
     * @throws SerialException if an error occurs serializing the
     *     <code>Array</code> object
     * @throws SQLException if a database access error occurs or the
     *     <i>array</i> parameter is <code>null</code>.
     */
     public SerialArray(Array array) throws SerialException, SQLException {
         if (array == null) {
             throw new SQLException("Cannot instantiate a SerialArray " +
                 "object with a null Array object");
         }

         if ((elements = (Object[])array.getArray()) == null) {
             throw new SQLException("Invalid Array object. Calls to Array.getArray() " +
                 "return null value which cannot be serialized");
         }

         //elements = (Object[])array.getArray();
         baseType = array.getBaseType();
         baseTypeName = array.getBaseTypeName();
         len = elements.length;

        switch (baseType) {

        case java.sql.Types.BLOB:
            for (int i = 0; i < len; i++) {
                elements[i] = new SerialBlob((Blob)elements[i]);
            }
            break;

        case java.sql.Types.CLOB:
            for (int i = 0; i < len; i++) {
                elements[i] = new SerialClob((Clob)elements[i]);
            }
            break;

        case java.sql.Types.DATALINK:
            for (int i = 0; i < len; i++) {
                elements[i] = new SerialDatalink((URL)elements[i]);
            }
            break;

        case java.sql.Types.JAVA_OBJECT:
            for (int i = 0; i < len; i++) {
                elements[i] = new SerialJavaObject(elements[i]);
            }
            break;

        }


    }

    /**
     * Returns a new array that is a copy of this <code>SerialArray</code>
     * object.
     *
     * @return a copy of this <code>SerialArray</code> object as an
     *         <code>Object</code> in the Java programming language
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public Object getArray() throws SerialException {
        isValid();
        Object dst = new Object[len];
        System.arraycopy((Object)elements, 0, dst, 0, len);
        return dst;
    }

    /**
     * Returns a new array that is a copy of this <code>SerialArray</code>
     * object, using the given type map for the custom
     * mapping of each element when the elements are SQL UDTs.
     * <P>
     * This method does custom mapping if the array elements are a UDT
     * and the given type map has an entry for that UDT.
     * Custom mapping is recursive,
     * meaning that if, for instance, an element of an SQL structured type
     * is an SQL structured type that itself has an element that is an SQL
     * structured type, each structured type that has a custom mapping will be
     * mapped according to the given type map.
     *
     * @param map a <code>java.util.Map</code> object in which
     *        each entry consists of 1) a <code>String</code> object
     *        giving the fully qualified name of a UDT and 2) the
     *        <code>Class</code> object for the <code>SQLData</code> implementation
     *        that defines how the UDT is to be mapped
     * @return a copy of this <code>SerialArray</code> object as an
     *         <code>Object</code> in the Java programming language
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public Object getArray(Map<String, Class<?>> map) throws SerialException {
        isValid();
        Object dst[] = new Object[len];
        System.arraycopy((Object)elements, 0, dst, 0, len);
        return dst;
    }

    /**
     * Returns a new array that is a copy of a slice
     * of this <code>SerialArray</code> object, starting with the
     * element at the given index and containing the given number
     * of consecutive elements.
     *
     * @param index the index into this <code>SerialArray</code> object
     *              of the first element to be copied;
     *              the index of the first element is <code>0</code>
     * @param count the number of consecutive elements to be copied, starting
     *              at the given index
     * @return a copy of the designated elements in this <code>SerialArray</code>
     *         object as an <code>Object</code> in the Java programming language
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public Object getArray(long index, int count) throws SerialException {
        isValid();
        Object dst = new Object[count];
        System.arraycopy((Object)elements, (int)index, dst, 0, count);
        return dst;
    }

    /**
     * Returns a new array that is a copy of a slice
     * of this <code>SerialArray</code> object, starting with the
     * element at the given index and containing the given number
     * of consecutive elements.
     * <P>
     * This method does custom mapping if the array elements are a UDT
     * and the given type map has an entry for that UDT.
     * Custom mapping is recursive,
     * meaning that if, for instance, an element of an SQL structured type
     * is an SQL structured type that itself has an element that is an SQL
     * structured type, each structured type that has a custom mapping will be
     * mapped according to the given type map.
     *
     * @param index the index into this <code>SerialArray</code> object
     *              of the first element to be copied; the index of the
     *              first element in the array is <code>0</code>
     * @param count the number of consecutive elements to be copied, starting
     *              at the given index
     * @param map a <code>java.util.Map</code> object in which
     *        each entry consists of 1) a <code>String</code> object
     *        giving the fully qualified name of a UDT and 2) the
     *        <code>Class</code> object for the <code>SQLData</code> implementation
     *        that defines how the UDT is to be mapped
     * @return a copy of the designated elements in this <code>SerialArray</code>
     *         object as an <code>Object</code> in the Java programming language
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public Object getArray(long index, int count, Map<String,Class<?>> map)
        throws SerialException
    {
        isValid();
        Object dst = new Object[count];
        System.arraycopy((Object)elements, (int)index, dst, 0, count);
        return dst;
    }

    /**
     * Retrieves the SQL type of the elements in this <code>SerialArray</code>
     * object.  The <code>int</code> returned is one of the constants in the class
     * <code>java.sql.Types</code>.
     *
     * @return one of the constants in <code>java.sql.Types</code>, indicating
     *         the SQL type of the elements in this <code>SerialArray</code> object
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public int getBaseType() throws SerialException {
        isValid();
        return baseType;
    }

    /**
     * Retrieves the DBMS-specific type name for the elements in this
     * <code>SerialArray</code> object.
     *
     * @return the SQL type name used by the DBMS for the base type of this
     *         <code>SerialArray</code> object
     * @throws SerialException if an error occurs;
     * if {@code free} had previously been called on this object
     */
    public String getBaseTypeName() throws SerialException {
        isValid();
        return baseTypeName;
    }

    /**
     * Retrieves a <code>ResultSet</code> object holding the elements of
     * the subarray that starts at
     * index <i>index</i> and contains up to <i>count</i> successive elements.
     * This method uses the connection's type map to map the elements of
     * the array if the map contains
     * an entry for the base type. Otherwise, the standard mapping is used.
     *
     * @param index the index into this <code>SerialArray</code> object
     *         of the first element to be copied; the index of the
     *         first element in the array is <code>0</code>
     * @param count the number of consecutive elements to be copied, starting
     *         at the given index
     * @return a <code>ResultSet</code> object containing the designated
     *         elements in this <code>SerialArray</code> object, with a
     *         separate row for each element
     * @throws SerialException if called with the cause set to
     *         {@code UnsupportedOperationException}
     */
    public ResultSet getResultSet(long index, int count) throws SerialException {
        SerialException se = new SerialException();
        se.initCause(new UnsupportedOperationException());
        throw  se;
    }

    /**
     *
     * Retrieves a <code>ResultSet</code> object that contains all of
     * the elements of the SQL <code>ARRAY</code>
     * value represented by this <code>SerialArray</code> object. This method uses
     * the specified map for type map customizations unless the base type of the
     * array does not match a user-defined type (UDT) in <i>map</i>, in
     * which case it uses the
     * standard mapping. This version of the method <code>getResultSet</code>
     * uses either the given type map or the standard mapping; it never uses the
     * type map associated with the connection.
     *
     * @param map a <code>java.util.Map</code> object in which
     *        each entry consists of 1) a <code>String</code> object
     *        giving the fully qualified name of a UDT and 2) the
     *        <code>Class</code> object for the <code>SQLData</code> implementation
     *        that defines how the UDT is to be mapped
     * @return a <code>ResultSet</code> object containing all of the
     *         elements in this <code>SerialArray</code> object, with a
     *         separate row for each element
     * @throws SerialException if called with the cause set to
     *         {@code UnsupportedOperationException}
     */
    public ResultSet getResultSet(Map<String, Class<?>> map)
        throws SerialException
    {
        SerialException se = new SerialException();
        se.initCause(new UnsupportedOperationException());
        throw  se;
    }

    /**
     * Retrieves a <code>ResultSet</code> object that contains all of
     * the elements in the <code>ARRAY</code> value that this
     * <code>SerialArray</code> object represents.
     * If appropriate, the elements of the array are mapped using the connection's
     * type map; otherwise, the standard mapping is used.
     *
     * @return a <code>ResultSet</code> object containing all of the
     *         elements in this <code>SerialArray</code> object, with a
     *         separate row for each element
     * @throws SerialException if called with the cause set to
     *         {@code UnsupportedOperationException}
     */
    public ResultSet getResultSet() throws SerialException {
        SerialException se = new SerialException();
        se.initCause(new UnsupportedOperationException());
        throw  se;
    }


    /**
     * Retrieves a result set holding the elements of the subarray that starts at
     * Retrieves a <code>ResultSet</code> object that contains a subarray of the
     * elements in this <code>SerialArray</code> object, starting at
     * index <i>index</i> and containing up to <i>count</i> successive
     * elements. This method uses
     * the specified map for type map customizations unless the base type of the
     * array does not match a user-defined type (UDT) in <i>map</i>, in
     * which case it uses the
     * standard mapping. This version of the method <code>getResultSet</code> uses
     * either the given type map or the standard mapping; it never uses the type
     * map associated with the connection.
     *
     * @param index the index into this <code>SerialArray</code> object
     *              of the first element to be copied; the index of the
     *              first element in the array is <code>0</code>
     * @param count the number of consecutive elements to be copied, starting
     *              at the given index
     * @param map a <code>java.util.Map</code> object in which
     *        each entry consists of 1) a <code>String</code> object
     *        giving the fully qualified name of a UDT and 2) the
     *        <code>Class</code> object for the <code>SQLData</code> implementation
     *        that defines how the UDT is to be mapped
     * @return a <code>ResultSet</code> object containing the designated
     *         elements in this <code>SerialArray</code> object, with a
     *         separate row for each element
     * @throws SerialException if called with the cause set to
     *         {@code UnsupportedOperationException}
     */
    public ResultSet getResultSet(long index, int count,
                                  Map<String,Class<?>> map)
        throws SerialException
    {
        SerialException se = new SerialException();
        se.initCause(new UnsupportedOperationException());
        throw  se;
    }


    /**
     * Compares this SerialArray to the specified object.  The result is {@code
     * true} if and only if the argument is not {@code null} and is a {@code
     * SerialArray} object whose elements are identical to this object's elements
     *
     * @param  obj The object to compare this {@code SerialArray} against
     *
     * @return  {@code true} if the given object represents a {@code SerialArray}
     *          equivalent to this SerialArray, {@code false} otherwise
     *
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (obj instanceof SerialArray) {
            SerialArray sa = (SerialArray)obj;
            return baseType == sa.baseType &&
                    baseTypeName.equals(sa.baseTypeName) &&
                    Arrays.equals(elements, sa.elements);
        }
        return false;
    }

    /**
     * Returns a hash code for this SerialArray. The hash code for a
     * {@code SerialArray} object is computed using the hash codes
     * of the elements of the  {@code SerialArray} object
     *
     * @return  a hash code value for this object.
     */
    public int hashCode() {
        return (((31 + Arrays.hashCode(elements)) * 31 + len)  * 31 +
                baseType) * 31 + baseTypeName.hashCode();
    }

    /**
     * Returns a clone of this {@code SerialArray}. The copy will contain a
     * reference to a clone of the underlying objects array, not a reference
     * to the original underlying object array of this {@code SerialArray} object.
     *
     * @return a clone of this SerialArray
     */
    public Object clone() {
        try {
            SerialArray sa = (SerialArray) super.clone();
            sa.elements = (elements != null) ? Arrays.copyOf(elements, len) : null;
            return sa;
        } catch (CloneNotSupportedException ex) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError();
        }

    }

    /**
     * readObject is called to restore the state of the {@code SerialArray} from
     * a stream.
     * @param s the {@code ObjectInputStream} to read from.
     *
     * @throws  ClassNotFoundException if the class of a serialized object
     *          could not be found.
     * @throws  IOException if an I/O error occurs.
     */
    private void readObject(ObjectInputStream s)
            throws IOException, ClassNotFoundException {

       ObjectInputStream.GetField fields = s.readFields();
       Object[] tmp = (Object[])fields.get("elements", null);
       if (tmp == null)
           throw new InvalidObjectException("elements is null and should not be!");
       elements = tmp.clone();
       len = fields.get("len", 0);
       if(elements.length != len)
           throw new InvalidObjectException("elements is not the expected size");

       baseType = fields.get("baseType", 0);
       baseTypeName = (String)fields.get("baseTypeName", null);
    }

    /**
     * writeObject is called to save the state of the {@code SerialArray}
     * to a stream.
     * @param s the {@code ObjectOutputStream} to write to.
     * @throws  IOException if an I/O error occurs.
     */
    private void writeObject(ObjectOutputStream s)
            throws IOException {

        ObjectOutputStream.PutField fields = s.putFields();
        fields.put("elements", elements);
        fields.put("len", len);
        fields.put("baseType", baseType);
        fields.put("baseTypeName", baseTypeName);
        s.writeFields();
    }

    /**
     * Check to see if this object had previously had its {@code free} method
     * called
     *
     * @throws SerialException
     */
    private void isValid() throws SerialException {
        if (elements == null) {
            throw new SerialException("Error: You cannot call a method on a "
                    + "SerialArray instance once free() has been called.");
        }
    }

    /**
     * The identifier that assists in the serialization of this <code>SerialArray</code>
     * object.
     */
    static final long serialVersionUID = -8466174297270688520L;
}