0
# Enterprise JavaBeans
1

2
EJB API for developing enterprise business components with transaction management, security, and lifecycle support.
3

4
## Session Bean Annotations
5

6
```java { .api }
7
@Target({ElementType.TYPE})
8
@Retention(RetentionPolicy.RUNTIME)
9
public @interface Stateless {
10
    String name() default "";
11
    String mappedName() default "";
12
    String description() default "";
13
}
14

15
@Target({ElementType.TYPE})
16
@Retention(RetentionPolicy.RUNTIME)
17
public @interface Stateful {
18
    String name() default "";
19
    String mappedName() default "";
20
    String description() default "";
21
    String passivationCapable() default "";
22
}
23

24
@Target({ElementType.TYPE})
25
@Retention(RetentionPolicy.RUNTIME)
26
public @interface Singleton {
27
    String name() default "";
28
    String mappedName() default "";
29
    String description() default "";
30
}
31
```
32

33
## EJB Context
34

35
```java { .api }
36
public interface EJBContext {
37
    EJBHome getEJBHome() throws IllegalStateException;
38
    EJBLocalHome getEJBLocalHome() throws IllegalStateException;
39
    Properties getEnvironment();
40
    Identity getCallerIdentity();
41
    Principal getCallerPrincipal();
42
    boolean isCallerInRole(Identity role);
43
    boolean isCallerInRole(String roleName);
44
    UserTransaction getUserTransaction() throws IllegalStateException;
45
    void setRollbackOnly() throws IllegalStateException;
46
    boolean getRollbackOnly() throws IllegalStateException;
47
    TimerService getTimerService() throws IllegalStateException;
48
    Object lookup(String name) throws IllegalArgumentException;
49
    Map<String, Object> getContextData();
50
}
51
```
52

53
## Lifecycle Callbacks
54

55
```java { .api }
56
@Target({ElementType.METHOD})
57
@Retention(RetentionPolicy.RUNTIME)
58
public @interface PostConstruct;
59

60
@Target({ElementType.METHOD})
61
@Retention(RetentionPolicy.RUNTIME)
62
public @interface PreDestroy;
63

64
@Target({ElementType.METHOD})
65
@Retention(RetentionPolicy.RUNTIME)
66
public @interface PostActivate;
67

68
@Target({ElementType.METHOD})
69
@Retention(RetentionPolicy.RUNTIME)
70
public @interface PrePassivate;
71
```
72

73
## Usage Example
74

75
```java
76
@Stateless
77
public class UserService {
78
    
79
    @PersistenceContext
80
    private EntityManager em;
81
    
82
    @PostConstruct
83
    public void init() {
84
        // Initialization logic
85
    }
86
    
87
    public User findUser(Long id) {
88
        return em.find(User.class, id);
89
    }
90
    
91
    @PreDestroy
92
    public void cleanup() {
93
        // Cleanup logic
94
    }
95
}
96
```