《我要进大厂》- Spring/SpringBoot 常用注解 夺命连环11问，你能坚持到第几问？（Spring/SpringBoot注解篇）（二）

@Component
@PropertySource("classpath:website.properties")
class WebSite {
    @Value("${url}")
    private String url;
  省略getter/setter
  ......
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Person {
    @NotNull(message = "classId 不能为空")
    private String classId;
    @Size(max = 33)
    @NotNull(message = "name 不能为空")
    private String name;
    @Pattern(regexp = "((^Man$|^Woman$|^UGM$))", message = "sex 值不在可选范围")
    @NotNull(message = "sex 不能为空")
    private String sex;
    @Email(message = "email 格式不正确")
    @NotNull(message = "email 不能为空")
    private String email;
}

@RestController
@RequestMapping("/api")
public class PersonController {
    @PostMapping("/person")
    public ResponseEntity<Person> getPerson(@RequestBody @Valid Person person) {
        return ResponseEntity.ok().body(person);
    }
}

@RestController
@RequestMapping("/api")
@Validated
public class PersonController {
    @GetMapping("/person/{id}")
    public ResponseEntity<Integer> getPersonByID(@Valid @PathVariable("id") @Max(value = 5,message = "超过 id 的范围了") Integer id) {
        return ResponseEntity.ok().body(id);
    }
}

@ControllerAdvice
@ResponseBody
public class GlobalExceptionHandler {
    /**
     * 请求参数异常处理
     */
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResponseEntity<?> handleMethodArgumentNotValidException(MethodArgumentNotValidException ex, HttpServletRequest request) {
       ......
    }
}

@Entity
@Table(name = "role")
public class Role {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String description;
    省略getter/setter......
}

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

public enum GenerationType {
    /**
     * 使用一个特定的数据库表格来保存主键
     * 持久化引擎通过关系数据库的一张特定的表格来生成主键,
     */
    TABLE,
    /**
     *在某些数据库中,不支持主键自增长,比如Oracle、PostgreSQL其提供了一种叫做"序列(sequence)"的机制生成主键
     */
    SEQUENCE,
    /**
     * 主键自增长
     */
    IDENTITY,
    /**
     *把主键生成策略交给持久化引擎(persistence engine),
     *持久化引擎会根据数据库在以上三种主键生成 策略中选择其中一种
     */
    AUTO
}

public @interface GeneratedValue {
    GenerationType strategy() default AUTO;
    String generator() default "";
}

@Id
@GeneratedValue(generator = "IdentityIdGenerator")
@GenericGenerator(name = "IdentityIdGenerator", strategy = "identity")
private Long id;

public class DefaultIdentifierGeneratorFactory
    implements MutableIdentifierGeneratorFactory, Serializable, ServiceRegistryAwareService {
  @SuppressWarnings("deprecation")
  public DefaultIdentifierGeneratorFactory() {
    register( "uuid2", UUIDGenerator.class );
    register( "guid", GUIDGenerator.class );      // can be done with UUIDGenerator + strategy
    register( "uuid", UUIDHexGenerator.class );     // "deprecated" for new use
    register( "uuid.hex", UUIDHexGenerator.class );   // uuid.hex is deprecated
    register( "assigned", Assigned.class );
    register( "identity", IdentityGenerator.class );
    register( "select", SelectGenerator.class );
    register( "sequence", SequenceStyleGenerator.class );
    register( "seqhilo", SequenceHiLoGenerator.class );
    register( "increment", IncrementGenerator.class );
    register( "foreign", ForeignGenerator.class );
    register( "sequence-identity", SequenceIdentityGenerator.class );
    register( "enhanced-sequence", SequenceStyleGenerator.class );
    register( "enhanced-table", TableGenerator.class );
  }
  public void register(String strategy, Class generatorClass) {
    LOG.debugf( "Registering IdentifierGenerator strategy [%s] -> [%s]", strategy, generatorClass.getName() );
    final Class previous = generatorStrategyToClassNameMap.put( strategy, generatorClass );
    if ( previous != null ) {
      LOG.debugf( "    - overriding [%s]", previous.getName() );
    }
  }
}

@Column(name = "user_name", nullable = false, length=32)
private String userName;

@Entity(name="USER")
public class User {
    ......
    @Transient
    private String secrect; // not persistent because of @Transient
}

static String secrect; // not persistent because of static
final String secrect = "Satish"; // not persistent because of final
transient String secrect; // not persistent because of transient