stringtype.java

开源的axion的数据库代码

/*
 * $Id: StringType.java,v 1.5 2003/05/14 19:07:30 rwald Exp $
 * =======================================================================
 * Copyright (c) 2002-2003 Axion Development Team.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The names "Tigris", "Axion", nor the names of its contributors may
 *    not be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * 4. Products derived from this software may not be called "Axion", nor
 *    may "Tigris" or "Axion" appear in their names without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * =======================================================================
 */

package org.axiondb.types;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.sql.DatabaseMetaData;

import org.axiondb.DataType;

/**
 * A {@link DataType} representing a {@link String} value.
 *
 * @version $Revision: 1.5 $ $Date: 2003/05/14 19:07:30 $
 * @author Chuck Burdick
 * @author Rodney Waldhoff
 */
public class StringType extends BaseDataType {

    public StringType() {
    }

    public int getJdbcType() {
        return java.sql.Types.VARCHAR;
    }

    public String getPreferredValueClassName() {
        return "java.lang.String";
    }

    public int getColumnDisplaySize() {
        return 32;
    }
    
    public boolean isCaseSensitive() {
        return true;
    }

    /**
     * Returns <code>"string"</code>
     * @return <code>"string"</code>
     */
    public String toString() {
        return "string";
    }

    /**
     * Returns <code>true</code> iff <i>value</i> is <code>null</code>
     * or a {@link String String}.
     */
    public boolean accepts(Object value) {
        return true;
    }

    /**
     * Returns a {@link String} converted from the given <i>value</i>,
     * or throws {@link IllegalArgumentException} if the given <i>value</i>
     * isn't {@link #accepts acceptable}.
     */
    public Object convert(Object value) throws IllegalArgumentException {
        if(value instanceof String) {
            return (String)value;
        } else if(null == value) {
            return null;
        } else {
            return String.valueOf(value);
        }
    }

    public boolean supportsSuccessor() {
        return true;
    }

    public Object successor(Object value) throws IllegalArgumentException {
        String v = ((String)value);
        return v + "\0";
    }

    /**
     * @see #write
     */
    public Object read(DataInput in) throws IOException {
        String val = in.readUTF();
        if("null".equals(val)) {
            if(!in.readBoolean()) {
                return null;
            }
        }
        return val;
    }

    /**
     * Writes the given <i>value</i> to the given <code>DataOutput</code>.
     * <code>Null</code> values are written as <code>"null", false</code>,
     * the non-null String <code>"null"</code> is written as
     * <code>"null", true</code>, all other values are written directly.
     *
     * @param value the value to write, which must be {@link #accepts acceptable}
     */
    public void write(Object value, DataOutput out) throws IOException {
        if(null == value) {
            out.writeUTF("null");
            out.writeBoolean(false);
        } else if("null".equals(value)) {
            out.writeUTF("null");
            out.writeBoolean(true);
        } else {
            out.writeUTF( (String)value );
        }
    }

    public DataType makeNewInstance() {
        return new StringType();
    }

    public String getLiteralPrefix() {
        return "'";
    }

    public String getLiteralSuffix() {
        return "'";
    }

    public short getSearchableCode() {
        return DatabaseMetaData.typeSearchable;
    }
}