Java SQL Clob convert(Object o, Class targetType)

Description

convert

License

Open Source License

Declaration

public static Object convert(Object o, Class<?> targetType) 

Method Source Code

//package com.java2s;
/*//  www  . j a v a 2  s  . c  o m
 * Copyright 2004-2011 H2 Group. Multiple-Licensed under the H2 License,
 * Version 1.0, and under the Eclipse Public License, Version 1.0
 * (http://h2database.com/html/license.html).
 * Initial Developer: H2 Group
 */

import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;

import java.sql.Clob;

public class Main {
    private static final int BUFFER_BLOCK_SIZE = 4 * 1024;

    public static Object convert(Object o, Class<?> targetType) {
        if (o == null) {
            return null;
        }
        Class<?> currentType = o.getClass();
        if (targetType.isAssignableFrom(currentType)) {
            return o;
        }
        if (targetType == String.class) {
            if (Clob.class.isAssignableFrom(currentType)) {
                Clob c = (Clob) o;
                try {
                    Reader r = c.getCharacterStream();
                    return readStringAndClose(r, -1);
                } catch (Exception e) {
                    throw new RuntimeException("Error converting CLOB to String: " + e.toString(), e);
                }
            }
            return o.toString();
        }
        if (Number.class.isAssignableFrom(currentType)) {
            Number n = (Number) o;
            if (targetType == Byte.class) {
                return n.byteValue();
            } else if (targetType == Short.class) {
                return n.shortValue();
            } else if (targetType == Integer.class) {
                return n.intValue();
            } else if (targetType == Long.class) {
                return n.longValue();
            } else if (targetType == Double.class) {
                return n.doubleValue();
            } else if (targetType == Float.class) {
                return n.floatValue();
            }
        }
        throw new RuntimeException("Can not convert the value " + o + " from " + currentType + " to " + targetType);
    }

    /**
     * Read a number of characters from a reader and close it.
     *
     * @param in the reader
     * @param length the maximum number of characters to read, or -1 to read
     *            until the end of file
     * @return the string read
     */
    public static String readStringAndClose(Reader in, int length) throws IOException {
        try {
            if (length <= 0) {
                length = Integer.MAX_VALUE;
            }
            int block = Math.min(BUFFER_BLOCK_SIZE, length);
            StringWriter out = new StringWriter(length == Integer.MAX_VALUE ? block : length);
            char[] buff = new char[block];
            while (length > 0) {
                int len = Math.min(block, length);
                len = in.read(buff, 0, len);
                if (len < 0) {
                    break;
                }
                out.write(buff, 0, len);
                length -= len;
            }
            return out.toString();
        } finally {
            in.close();
        }
    }
}

Related

1. convertClob2String(Clob clob)
2. ConvertClobToString(StringBuffer sb, Clob clob)
3. convertToString(Object obj)
4. getClobToString(Clob clob)