1 package cz.cuni.amis.pogamut.base.factory.guice;
2
3 import com.google.inject.Guice;
4 import com.google.inject.Injector;
5
6 import cz.cuni.amis.utils.NullCheck;
7
8 /**
9 * Abstract Guice-based factory that uses {@link GuiceAgentModule} for the bindings.
10 * <p><p>
11 * It simply wraps the Guice's {@link Injector}, which it creates based on the passed module.
12 * <p><p>
13 * The module can be reset using {@link AbstractGuiceAgentFactory#setAgentModule(GuiceAgentModule)}.
14 *
15 * @author Jimmy
16 */
17 public abstract class AbstractGuiceAgentFactory {
18
19 /**
20 * Custom module used to initialize the {@link AbstractGuiceAgentFactory#injector}.
21 */
22 private GuiceAgentModule module;
23
24 /**
25 * Injector created using {@link AbstractGuiceAgentFactory#module}. Lazy-initialized inside {@link AbstractGuiceAgentFactory#getInjector()}.
26 */
27 private Injector injector;
28
29 /**
30 * Parameter-less constructor that can be utilized in situations when you have to set the {@link GuiceAgentModule}
31 * later. (DO NOT FORGET TO DO IT VIA {@link AbstractGuiceAgentFactory#setAgentModule(GuiceAgentModule)} :-)
32 */
33 public AbstractGuiceAgentFactory() {
34 }
35
36 /**
37 * Creates a Guice-based factory that will use {@link Injector} created using the 'module'.
38 *
39 * @param module module that configures bindings between classes, may be null (specify module later using {@link AbstractGuiceAgentFactory#setAgentModule(GuiceAgentModule)})
40 */
41 public AbstractGuiceAgentFactory(GuiceAgentModule module) {
42 this.module = module;
43 }
44
45 /**
46 * Returns the module that the factory is working with. Can be utilized to slip run-time dependencies
47 * into the module.
48 *
49 * @return factory module
50 */
51 protected GuiceAgentModule getAgentModule() {
52 return module;
53 }
54
55 /**
56 * Sets new agent module into the factory, it invalidates the {@link AbstractGuiceAgentFactory#injector}
57 * so the new one is created when {@link AbstractGuiceAgentFactory#getInjector()} is called.
58 *
59 * @param module new module
60 */
61 protected synchronized void setAgentModule(GuiceAgentModule module) {
62 if (module == this.module) return;
63 this.module = module;
64 this.injector = null;
65 }
66
67 /**
68 * Injector that should be used to instantiates new objects according to the module.
69 * <p><p>
70 * Lazy-initialized using {@link GuiceAgentFactory#getAgentModule()}.
71 *
72 * @return injector configured by {@link GuiceAgentFactory#getAgentModule()}
73 */
74 protected synchronized Injector getInjector() {
75 if (this.injector == null) {
76 GuiceAgentModule module = getAgentModule();
77 NullCheck.check(module, "getAgentModule()");
78 this.injector = Guice.createInjector(module);
79 NullCheck.check(this.injector, "Guice.createInjector(getAgentModule())");
80 }
81 return this.injector;
82 }
83
84 }