Most efficient solution for reading CLOB to String, and String to CLOB in Java?

java stringbuilder clob
Jonas picture Jonas · Jan 30, 2010 · Viewed 152.2k times · Source

I have a big CLOB (more than 32kB) that I want to read to a String, using StringBuilder. How do I do this in the most efficient way? I can not use the "int length" constructor for StringBuilder since the lenght of my CLOB is longer than a "int" and needs a "long" value.

I am not that confortable with the Java I/O classes, and would like to get some guidance.

Edit - I have tried with this code for clobToString():

private String clobToString(Clob data) {
    StringBuilder sb = new StringBuilder();
    try {
        Reader reader = data.getCharacterStream();
        BufferedReader br = new BufferedReader(reader);

        String line;
        while(null != (line = br.readLine())) {
            sb.append(line);
        }
        br.close();
    } catch (SQLException e) {
        // handle this exception
    } catch (IOException e) {
        // handle this exception
    }
    return sb.toString();
}

Answer

Omar Al Kababji picture Omar Al Kababji · Jan 30, 2010

Ok I will suppose a general use, first you have to download apache commons, there you will find an utility class named IOUtils which has a method named copy();

Now the solution is: get the input stream of your CLOB object using getAsciiStream() and pass it to the copy() method.

InputStream in = clobObject.getAsciiStream();
StringWriter w = new StringWriter();
IOUtils.copy(in, w);
String clobAsString = w.toString();

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