/**
* Decodes a String from the database representing a clob object. See getDbDescription().
*
* @param os an ObjectStore that the clob is stored in
* @param description the description from the database
* @return a ClobAccess object, or a subclass
*/
public static ClobAccess decodeDbDescription(ObjectStore os, String description) {
String[] parts = description.split(",");
ClobAccess clob = new ClobAccess(os, new Clob(Integer.parseInt(parts[0])));
if (parts.length >= 3) {
int offset = Integer.parseInt(parts[1]);
int length = Integer.parseInt(parts[2]);
clob = clob.subSequence(offset, offset + length);
}
String className = null;
if (parts.length == 2) {
className = parts[1];
} else if (parts.length == 4) {
className = parts[3];
}
if (className != null) {
// So, className is a class that extends ClobAccess. We expect there to be a static
// method called getFactory() that returns a ClobAccessSubclassFactory object that we
// can store in a cache, which will call the constructor quickly.
Map<String, ClobAccessSubclassFactory> factoryCache = subclassFactoryCache.get();
ClobAccessSubclassFactory factory = factoryCache.get(className);
if (factory == null) {
try {
Class<?> subclass = Class.forName(className);
Method subMethod = subclass.getMethod("getFactory");
factory = (ClobAccessSubclassFactory) subMethod.invoke(null);
factoryCache.put(className, factory);
} catch (ClassNotFoundException e) {
throw new RuntimeException(
"Could not read Clob subclass " + className + " from database.", e);
} catch (NoSuchMethodException e) {
throw new RuntimeException(
"Could not read Clob subclass " + className + " from database.", e);
} catch (InvocationTargetException e) {
throw new RuntimeException(
"Could not read Clob subclass " + className + " from database.", e);
} catch (IllegalAccessException e) {
throw new RuntimeException(
"Could not read Clob subclass " + className + " from database.", e);
}
}
clob = factory.invokeConstructor(clob);
}
return clob;
}
public void testClob() throws Exception {
Clob clob = writer.createClob();
writer.replaceClob(clob, "Monkey");
ClobAccess ca = new ClobAccess(writer, clob);
assertEquals("Monkey", ca.toString());
StringBuilder longString = new StringBuilder();
for (int i = 0; i < 10000; i++) {
longString.append("Lots of monkeys. ");
}
writer.replaceClob(clob, longString.toString());
assertEquals("Monkey", ca.toString());
ca = new ClobAccess(writer, clob);
assertEquals(170000, ca.length());
assertEquals(longString.toString(), ca.toString());
assertEquals('L', ca.charAt(1700));
assertEquals('L', ca.charAt(16983));
ClobAccess sub = ca.subSequence(85000, 85016);
assertEquals("Lots of monkeys.", sub.toString());
assertEquals(16, sub.length());
}