Interpret the "identity mapping 'framework design principle in the Java class library
Identity Mapping is a common design pattern in the Java class library, which is used to maximize the identity of an object to a identifier.In this framework, the identifier can be the value of any of the object, such as the primary key, memory address or customized unique identifier of the database table.
The identity mapping framework allows developers to manage the relationship between objects by using these identifies to improve the performance and maintenance of the application.The design principles of some identity mapping frameworks will be introduced below, and related Java code examples are provided.
1. Identifier Generator: The identity mapping framework usually provides a identifier generator to generate a unique identifier for each object.You can use an additional sequence, UUID (universal unique identifier) or other algorithms to generate identifiers.The following is an example of using UUID as a identifier:
import java.util.UUID;
public class IdentifierGenerator {
public static String generateIdentifier() {
return UUID.randomUUID().toString();
}
}
2. Identity Mapping Store: The identity mapping framework also provides a storage unit to save the mapping relationship between the object and its identifier.Storage can be implemented using hash tables, database tables or other data structures.The following is an example of using hash table implementation:
import java.util.HashMap;
public class IdentityMappingStore {
private final HashMap<String, Object> identityMap;
public IdentityMappingStore() {
identityMap = new HashMap<>();
}
public void addObject(String identifier, Object object) {
identityMap.put(identifier, object);
}
public Object getObject(String identifier) {
return identityMap.get(identifier);
}
public void removeObject(String identifier) {
identityMap.remove(identifier);
}
}
3. Identity Mapping Manager: The identity mapping framework usually also provides a manager for managing the mapping relationship between the object and the identifier.Manager allows developers to share and access the identity mapping storage on different contexts.The following is an example of a simple identity mapping manager:
public class IdentityMappingManager {
private static final IdentityMappingStore mappingStore = new IdentityMappingStore();
public static void addObject(String identifier, Object object) {
mappingStore.addObject(identifier, object);
}
public static Object getObject(String identifier) {
return mappingStore.getObject(identifier);
}
public static void removeObject(String identifier) {
mappingStore.removeObject(identifier);
}
}
Use identity mapping framework can bring the following benefits:
-A improve performance: By using identity mapping, you can avoid repeating the same objects, thereby reducing the consumption of memory and CPU resources.
-Simplify object relationship management: It can easily manage the relationship between objects through identifiers, without relying on complex relationship mapping configuration.
-Chopenize the object: the object can last for the longitudinality of the object to the database, thereby achieving the persistence of the object and sharing of cross -session.
In short, the identity mapping framework provides Java developers with a method of effective management and tracking object identity.Through the identifier, we can uniquely identify objects and share and access them in different contexts.This design model is particularly useful in the development of large applications, which can help us better organize and manage the relationship between objects.
