How to silently truncate strings while storing them when they are longer than the column length definition?

One can truncate a string according to the JPA annotations in the setter for the corresponding field:

public void setX(String x) {
    try {
        int size = getClass().getDeclaredField("x").getAnnotation(Column.class).length();
        int inLength = x.length();
        if (inLength>size)
        {
            x = x.substring(0, size);
        }
    } catch (NoSuchFieldException ex) {
    } catch (SecurityException ex) {
    }
    this.x = x;
}

The annotation itself should look like:

@Column(name = "x", length=100)
private String x;

(Based on https://stackoverflow.com/a/1946901/16673)

The annotations can be recreated from the database if the database changes, as hinted in the comment to https://stackoverflow.com/a/7648243/16673