How to convert a CLOB data type to a String in Hibernate?

user_1391249 0
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In hibernate (3.2.1.GA), I use the following method to insert CLOB type data into Oracle (10g) database.

Hibernate.createClob(parameters.get("txtCatImage"));

parameters is a Map where all the request parameters have been stored. While retrieving the Clob data type from the database directly something like this entityObj.getCatImage() would not work.

Seen this and this questions but couldn't find the way.

The following is the entity that uses a Clob type property.

public class Category  implements java.io.Serializable {

    private Long catId; // Primary key.
    private Clob catImage; // CLOB type field.
    // Other fields.
    private static final long serialVersionUID = 1L;

    public Category() {}

    // Overloaded constructs + getters + setters + hashcode() + equals() + toString().
}

The Clob field in the database just stores an image file name, in this case.

clob oracle10g hibernate spring
5 Answers

The solution from Dev (see above) to use "Clob.getSubString(long, int)" will be cost a lot of memory. I prefer the following solution.

private static String getAsString(Clob clob) {
    Reader reader = null;
    BufferedReader bufferedReader = null;
    try {
        reader = clob.getCharacterStream();
        bufferedReader = new BufferedReader(reader);
        return IOUtils.toString(bufferedReader);

    } catch (Exception e) {
        throw new RuntimeException("Error while reading String from CLOB", e);
    } finally {
        IOUtils.closeQuietly(reader);
        IOUtils.closeQuietly(bufferedReader);
    }
}
user_70478630

You can use this to read everything: 

new BufferedReader(new InputStreamReader(clob.getAsciiStream())).lines().collect(Collectors.joining());
user_36693100
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