Spring Boot Annotations — Master List

Topic 1: Application Bootstrap

1. @SpringBootApplication

  • Bootstraps the entire Spring Boot application
  • Parameters: scanBasePackages (packages to scan), exclude (auto-configs to disable)
  • Example: @SpringBootApplication(scanBasePackages = "com.akash")

2. @Configuration

  • Marks a class as a source of bean definitions
  • Parameters: proxyBeanMethods (default: true)
  • Example: @Configuration public class AppConfig {}

3. @ComponentScan

  • Tells Spring which packages to scan for beans
  • Parameters: basePackages, excludeFilters, includeFilters
  • Example: @ComponentScan(basePackages = "com.akash")

4. @EnableAutoConfiguration

  • Auto-configures beans based on classpath dependencies
  • Parameters: exclude (disable specific auto-configs), excludeName
  • Example: @EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})

Topic 2: Bean Annotations

5. @Component

  • Generic stereotype to register any class as a Spring bean
  • Parameters: value (custom bean name, default: className in camelCase)
  • Example: @Component("emailSvc") public class EmailService {}

6. @Service

  • Specialization of @Component for the business/service layer
  • Parameters: value (custom bean name)
  • Example: @Service public class UserService {}

7. @Repository

  • Specialization of @Component for data access layer; adds exception translation
  • Parameters: value (custom bean name)
  • Example: @Repository public class UserRepository {}

8. @Controller

  • Marks an MVC controller that handles web requests and returns view names
  • Parameters: value (custom bean name)
  • Example: @Controller public class UserController {}

9. @RestController

  • Combines @Controller + @ResponseBody; returns JSON/XML directly
  • Parameters: value (custom bean name)
  • Example: @RestController public class UserApi {}

10. @Bean

  • Manually declares a method's return value as a Spring bean
  • Parameters: name (bean name), initMethod, destroyMethod
  • Example: @Bean public PasswordEncoder encoder() { return new BCryptPasswordEncoder(); }

Topic 3: Scope & Lifecycle

11. @Scope

  • Controls how many instances Spring creates for a bean
  • Parameters: value (singleton / prototype / request / session), proxyMode
  • Example: @Scope("prototype")

12. @PostConstruct

  • Method runs once after dependency injection is complete
  • Parameters: none
  • Example: @PostConstruct public void init() { loadCache(); }

13. @PreDestroy

  • Method runs just before the bean is removed from the container
  • Parameters: none
  • Example: @PreDestroy public void cleanup() { connection.close(); }

Topic 4: Dependency Injection

14. @Autowired

  • Injects a matching bean automatically from the Spring container
  • Parameters: required (throw exception if no bean found, default: true)
  • Example: @Autowired private UserRepository repository;

15. @Primary

  • Marks one bean as the default when multiple candidates of the same type exist
  • Parameters: none
  • Example: @Primary @Component public class MySqlDatabase implements Database {}

16. @Qualifier

  • Explicitly names which bean to inject when multiple candidates exist
  • Parameters: value (bean name to inject — required)
  • Example: @Autowired @Qualifier("oracleDatabase") private Database db;

17. @Lazy

  • Delays bean creation until it is first accessed
  • Parameters: value (true = lazy, false = eager, default: true)
  • Example: @Lazy @Component public class HeavyReportService {}

18. @Value

  • Injects a value from application.properties or a hardcoded literal
  • Parameters: value (property placeholder or SpEL expression — required)
  • Example: @Value("${app.name}") private String appName;

19. @ConditionalOnProperty

  • Registers a bean only when a property exists and matches a given value
  • Parameters: name (property key), havingValue, matchIfMissing (default: false), prefix
  • Example: @ConditionalOnProperty(name = "app.cache.enabled", havingValue = "true")

Topic 5: Spring MVC & RESTful APIs — Presentation Layer

20. @RequestMapping

  • Maps HTTP requests to a controller class or method; base path for all routes in a controller
  • Parameters: value / path (URL), method (GET/POST etc.), produces, consumes
  • Example: @RequestMapping("/api/users")

21. @ResponseBody

  • Tells Spring to serialize the return value directly to HTTP response body as JSON/XML
  • Parameters: none
  • Example: @ResponseBody public User getUser() { return user; }

22. @GetMapping

  • Handles HTTP GET requests; used to fetch/read data
  • Parameters: value / path (URL), produces, params, headers
  • Example: @GetMapping("/users/{id}")

23. @PostMapping

  • Handles HTTP POST requests; used to create new resources
  • Parameters: value / path (URL), consumes, produces
  • Example: @PostMapping("/users")

24. @PutMapping

  • Handles HTTP PUT requests; used to replace an entire resource
  • Parameters: value / path (URL), consumes, produces
  • Example: @PutMapping("/users/{id}")

25. @PatchMapping

  • Handles HTTP PATCH requests; used to partially update a resource
  • Parameters: value / path (URL), consumes, produces
  • Example: @PatchMapping("/users/{id}")

26. @DeleteMapping

  • Handles HTTP DELETE requests; used to remove a resource
  • Parameters: value / path (URL), produces
  • Example: @DeleteMapping("/users/{id}")

27. @PathVariable

  • Extracts a value from the URL path and binds it to a method parameter
  • Parameters: value (path variable name), required (default: true)
  • Example: @GetMapping("/users/{id}") public User get(@PathVariable Long id)

28. @RequestParam

  • Extracts a query parameter from the URL and binds it to a method parameter
  • Parameters: value (param name), required (default: true), defaultValue
  • Example: @GetMapping("/users") public List<User> search(@RequestParam String name)

29. @RequestBody

  • Deserializes the HTTP request body (JSON/XML) into a Java object
  • Parameters: required (default: true)
  • Example: @PostMapping("/users") public User create(@RequestBody UserDto dto)

Topic 6: Persistence Layer & JPA

30. @Entity

  • Marks a class as a JPA entity mapped to a database table
  • Parameters: name (entity name, default: class name)
  • Example: @Entity public class User {}

31. @Table

  • Specifies the database table name and schema for an entity
  • Parameters: name (table name), schema, catalog, uniqueConstraints
  • Example: @Table(name = "departments")

32. @Id

  • Marks a field as the primary key of the entity
  • Parameters: none
  • Example: @Id private Long id;

33. @GeneratedValue

  • Defines the strategy for auto-generating primary key values
  • Parameters: strategy (AUTO / IDENTITY / SEQUENCE / TABLE), generator
  • Example: @GeneratedValue(strategy = GenerationType.IDENTITY)

34. @Column

  • Maps a field to a specific database column with custom constraints
  • Parameters: name, nullable (default: true), unique, length, insertable, updatable
  • Example: @Column(name = "email", nullable = false, unique = true)

35. @OneToMany

  • Defines a one-to-many relationship between two entities
  • Parameters: mappedBy, cascade, fetch (LAZY/EAGER), orphanRemoval
  • Example: @OneToMany(mappedBy = "department", cascade = CascadeType.ALL)

36. @ManyToOne

  • Defines a many-to-one relationship between two entities
  • Parameters: fetch (default: EAGER), cascade, optional
  • Example: @ManyToOne @JoinColumn(name = "dept_id") private Department dept;

37. @JoinColumn

  • Specifies the foreign key column for a relationship
  • Parameters: name (column name), nullable, unique, referencedColumnName
  • Example: @JoinColumn(name = "department_id")

Topic 7: Lombok Annotations

38. @Getter

  • Auto-generates getter methods for all fields (or a specific field)
  • Parameters: value (access level: PUBLIC/PROTECTED/PRIVATE, default: PUBLIC)
  • Example: @Getter public class User { private String name; }

39. @Setter

  • Auto-generates setter methods for all fields (or a specific field)
  • Parameters: value (access level, default: PUBLIC)
  • Example: @Setter public class User { private String name; }

40. @AllArgsConstructor

  • Generates a constructor with one parameter for every field
  • Parameters: access (access level), staticName (creates static factory method)
  • Example: @AllArgsConstructor public class User {}

41. @NoArgsConstructor

  • Generates a no-argument constructor (required by JPA)
  • Parameters: access (access level), force (initializes final fields to defaults)
  • Example: @NoArgsConstructor public class User {}

42. @RequiredArgsConstructor

  • Generates a constructor only for final and @NonNull fields
  • Parameters: access, staticName
  • Example: @RequiredArgsConstructor public class UserService {}

43. @Data

  • Shortcut for @Getter + @Setter + @ToString + @EqualsAndHashCode + @RequiredArgsConstructor
  • Parameters: staticConstructor
  • Example: @Data public class UserDto {}

44. @Builder

  • Generates a builder pattern for the class
  • Parameters: toBuilder (add toBuilder() method), builderClassName, buildMethodName
  • Example: @Builder public class User {} → User.builder().name("Akash").build()

45. @ToString

  • Generates a toString() method
  • Parameters: exclude (fields to skip), includeFieldNames (default: true), callSuper
  • Example: @ToString(exclude = "password")

Topic 8: JSON Annotations

46. @JsonProperty

  • Maps a Java field to a different JSON key name during serialization/deserialization
  • Parameters: value (JSON key name), access (READ_ONLY / WRITE_ONLY / READ_WRITE)
  • Example: @JsonProperty("full_name") private String fullName;

47. @JsonIgnore

  • Excludes a field from both serialization and deserialization
  • Parameters: value (default: true)
  • Example: @JsonIgnore private String password;

48. @JsonIgnoreProperties

  • Ignores unknown JSON properties or specified fields at class level
  • Parameters: value (field names to ignore), ignoreUnknown (default: false)
  • Example: @JsonIgnoreProperties(ignoreUnknown = true)

49. @JsonInclude

  • Controls when a field is included in serialization (e.g. skip nulls)
  • Parameters: value (NON_NULL / NON_EMPTY / ALWAYS / NON_DEFAULT)
  • Example: @JsonInclude(JsonInclude.Include.NON_NULL)

50. @JsonFormat

  • Specifies format for dates, numbers, or enums during serialization
  • Parameters: shape, pattern (date pattern), timezone
  • Example: @JsonFormat(pattern = "yyyy-MM-dd") private LocalDate dob;

Topic 9: Validation Annotations

51. @Valid

  • Triggers validation on a method parameter (cascades into nested objects)
  • Parameters: none
  • Example: public User create(@Valid @RequestBody UserDto dto)

52. @Validated

  • Spring's variant of @Valid; supports group-based validation
  • Parameters: value (validation groups)
  • Example: @Validated(OnCreate.class)

53. @NotNull

  • Field must not be null (empty string is allowed)
  • Parameters: message (custom error message), groups
  • Example: @NotNull(message = "Name is required") private String name;

54. @Null

  • Field must be null (rarely used, mainly for update-group scenarios)
  • Parameters: message, groups
  • Example: @Null private Long id;

55. @NotEmpty

  • Field must not be null and must have at least one character / element
  • Parameters: message, groups
  • Example: @NotEmpty private String username;

56. @NotBlank

  • Field must not be null, empty, or whitespace only (stricter than @NotEmpty)
  • Parameters: message, groups
  • Example: @NotBlank private String email;

57. @Pattern

  • Field must match a given regular expression
  • Parameters: regexp (regex — required), flags, message
  • Example: @Pattern(regexp = "^[0-9]{10}$") private String phone;

58. @Size

  • Validates length of strings, arrays, or collections
  • Parameters: min (default: 0), max (default: Integer.MAX_VALUE), message
  • Example: @Size(min = 2, max = 50) private String name;

59. @Min

  • Field value must be greater than or equal to the specified minimum
  • Parameters: value (minimum — required), message
  • Example: @Min(18) private int age;

60. @Max

  • Field value must be less than or equal to the specified maximum
  • Parameters: value (maximum — required), message
  • Example: @Max(100) private int score;

61. @Email

  • Field must be a valid email address format
  • Parameters: message, regexp (custom email regex), flags
  • Example: @Email private String email;

62. @Positive

  • Numeric field must be strictly greater than zero
  • Parameters: message, groups
  • Example: @Positive private int quantity;

63. @PositiveOrZero

  • Numeric field must be zero or greater
  • Parameters: message, groups
  • Example: @PositiveOrZero private int stock;

64. @Negative

  • Numeric field must be strictly less than zero
  • Parameters: message, groups
  • Example: @Negative private int temperature;

65. @NegativeOrZero

  • Numeric field must be zero or less
  • Parameters: message, groups
  • Example: @NegativeOrZero private int balance;

66. @Past

  • Date/time must be in the past (strictly before now)
  • Parameters: message, groups
  • Example: @Past private LocalDate birthDate;

67. @PastOrPresent

  • Date/time must be in the past or exactly now
  • Parameters: message, groups
  • Example: @PastOrPresent private LocalDate joinDate;

68. @Future

  • Date/time must be strictly in the future
  • Parameters: message, groups
  • Example: @Future private LocalDate expiryDate;

69. @FutureOrPresent

  • Date/time must be now or in the future
  • Parameters: message, groups
  • Example: @FutureOrPresent private LocalDate scheduledDate;

70. @Digits

  • Numeric field must have at most the specified integer and fraction digits
  • Parameters: integer (max integer digits — required), fraction (max fraction digits — required), message
  • Example: @Digits(integer = 6, fraction = 2) private BigDecimal price;

71. @DecimalMin

  • Field value must be greater than or equal to the given decimal string
  • Parameters: value (decimal string — required), inclusive (default: true), message
  • Example: @DecimalMin("0.1") private BigDecimal rate;

72. @DecimalMax

  • Field value must be less than or equal to the given decimal string
  • Parameters: value (decimal string — required), inclusive (default: true), message
  • Example: @DecimalMax("999.99") private BigDecimal price;

73. @AssertTrue

  • Boolean field must be true
  • Parameters: message, groups
  • Example: @AssertTrue private boolean termsAccepted;

74. @AssertFalse

  • Boolean field must be false
  • Parameters: message, groups
  • Example: @AssertFalse private boolean deleted;

75. @Constraint

  • Meta-annotation used to create custom validation annotations
  • Parameters: validatedBy (validator class — required)
  • Example: @Constraint(validatedBy = PhoneValidator.class) public @interface ValidPhone {}

Topic 10: Exception Handling

76. @ExceptionHandler

  • Handles specific exceptions thrown within a controller or globally
  • Parameters: value (exception class(es) to handle — required)
  • Example: @ExceptionHandler(ResourceNotFoundException.class) public ResponseEntity<?> handle(...)

77. @RestControllerAdvice

  • Global exception handler for all REST controllers; combines @ControllerAdvice + @ResponseBody
  • Parameters: basePackages, assignableTypes, annotations
  • Example: @RestControllerAdvice public class GlobalExceptionHandler {}

78. @ResponseStatus

  • Sets the HTTP status code returned by a handler method or exception class
  • Parameters: value / code (HttpStatus — required), reason (message)
  • Example: @ResponseStatus(HttpStatus.NOT_FOUND)


Tags

#Annotations #Java