不用java编码快速转换CLOB到String

Question

ResultSet rs = ... 
while (rs.next()){ 
   Clob clob = rs.getClob(3); 
   String s = clob.getSubString(1, MAX_TEXTITEM_LENGTH); 
   ... 

更新。麻烦在于：“By drivers使用SQL locator（Clob）实现Clob对象，这意味着Clob对象包含一个指向SQL Clob数据的逻辑指针，而不是数据本身。”如何将CLOB值内联（当我使用next（）时）？

附言。因为英语不好。

Answer 1

我尝试使用以下方法：

public static String clobToString(Clob data) {
    long dataL = System.currentTimeMillis();
    StringBuilder sb = new StringBuilder();
    if (data != null) {
        Reader reader = null;
        BufferedReader br = null;
        try {
            reader = data.getCharacterStream();
            br = new BufferedReader(reader);
            String line;
            while (null != (line = br.readLine())) {
                sb.append(line);
            }
        } catch (SQLException e) {
            logger.error(getClassAndMethodNameRuntime(), e);
        } catch (IOException e) {
            logger.error(getClassAndMethodNameRuntime(), e);
        } finally {
            closeObject(br);
            closeObject(reader);
        }
    }
    logger.trace("CLOB CONVERSION TIME1 ms: " + (System.currentTimeMillis() - dataL) + " Character: " + sb.length());
    return sb.toString();
}

和

public static String clobToString2(Clob data) {
    long dataL = System.nanoTime();
    String result = "";
    int MAX_TEXTITEM_LENGTH = 8000;

    if (data != null) {
        try {
            result = data.getSubString(1, MAX_TEXTITEM_LENGTH);
        } catch (SQLException e) {
            logger.error(getClassAndMethodNameRuntime(), e);
        }
    }
    logger.trace("CLOB CONVERSION TIME2 ms: " + ((double)(System.nanoTime() - dataL)) / 1000000 + " Character: " + result.length());
    return result;
}

转换时间变化很大：

null

select dbms_lob.substr(dettXML__C, 4000, 1) from TABLE