2.3. Caching and Retrieving Data
Next, lets use the
Cache API to access a Node in the cache and then do some simple reads and writes to that node.
// Let's get a hold of the root node.
Node rootNode = cache.getRoot();
// Remember, JBoss Cache stores data in a tree structure.
// All nodes in the tree structure are identified by Fqn objects.
Fqn peterGriffinFqn = Fqn.fromString("/griffin/peter");
// Create a new Node
Node peterGriffin = rootNode.addChild(peterGriffinFqn);
// let's store some data in the node
peterGriffin.put("isCartoonCharacter", Boolean.TRUE);
peterGriffin.put("favoriteDrink", new Beer());
// some tests (just assume this code is in a JUnit test case)
assertTrue(peterGriffin.get("isCartoonCharacter"));
assertEquals(peterGriffinFqn, peterGriffin.getFqn());
assertTrue(rootNode.hasChild(peterGriffinFqn));
Set keys = new HashSet();
keys.add("isCartoonCharacter");
keys.add("favoriteDrink");
assertEquals(keys, peterGriffin.getKeys());
// let's remove some data from the node
peterGriffin.remove("favoriteDrink");
assertNull(peterGriffin.get("favoriteDrink");
// let's remove the node altogether
rootNode.removeChild(peterGriffinFqn);
assertFalse(rootNode.hasChild(peterGriffinFqn));
The
Cache interface also exposes put/get/remove operations that take an Section 2.4, “ The Fqn Class ” as an argument, for convenience:
Fqn peterGriffinFqn = Fqn.fromString("/griffin/peter");
cache.put(peterGriffinFqn, "isCartoonCharacter", Boolean.TRUE);
cache.put(peterGriffinFqn, "favoriteDrink", new Beer());
assertTrue(peterGriffin.get(peterGriffinFqn, "isCartoonCharacter"));
assertTrue(cache.getRootNode().hasChild(peterGriffinFqn));
cache.remove(peterGriffinFqn, "favoriteDrink");
assertNull(cache.get(peterGriffinFqn, "favoriteDrink");
cache.removeNode(peterGriffinFqn);
assertFalse(cache.getRootNode().hasChild(peterGriffinFqn));
2.3.1. Organizing Your Data and Using the Node Structure
A Node should be viewed as a named logical grouping of data. A node should be used to contain data for a single data record, for example information about a particular person or account. It should be kept in mind that all aspects of the cache - locking, cache loading, replication and eviction - happen on a per-node basis. As such, anything grouped together by being stored in a single node will be treated as a single atomic unit.
