Java面试--SpringMVC常用的注解

标记这个类是一个SpringMVC Controller

标注在类或者method上面，使其的返回值是一个json字符串

这个注解结合了上面的注解的功能，是一个SpringMVC Controller 类并且返回值是一个json

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@documented
@Controller
@ResponseBody
public @interface RestController {
    @AliasFor(
        annotation = Controller.class
    )
    String value() default "";
}

实现前后端的跨域请求

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface CrossOrigin {
    
    @Deprecated
    String[] DEFAULT_ORIGINS = new String[]{"*"};
    
    @Deprecated
    String[] DEFAULT_ALLOWED_HEADERS = new String[]{"*"};
    
    @Deprecated
    boolean DEFAULT_ALLOW_CREDENTIALS = false;
    
    @Deprecated
    long DEFAULT_MAX_AGE = 1800L;

    @AliasFor("origins")
    String[] value() default {};

    @AliasFor("value")
    String[] origins() default {};

    String[] originPatterns() default {};

    String[] allowedHeaders() default {};

    String[] exposedHeaders() default {};

    RequestMethod[] methods() default {};

    String allowCredentials() default "";

    long maxAge() default -1L;
}

将实例对象放到容器中

@Target({ElementType.CONSTRUCTOR, ElementType.METHOD, ElementType.PARAMETER, ElementType.FIELD, ElementType.ANNOTATION_TYPE})
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface Autowired {
    boolean required() default true;
}

获取相应前端地址发送过来的任何形式的请求数据

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@documented
@Mapping
public @interface RequestMapping {
    String name() default "";

    @AliasFor("path")
    String[] value() default {};

    @AliasFor("value")
    String[] path() default {};

    RequestMethod[] method() default {};

    String[] params() default {};

    String[] headers() default {};

    String[] consumes() default {};

    String[] produces() default {};
}

@GetMapping
@PostMapping
@DeleteMapping
@PutMapping
这四个注解分别是接受了get、post、delete、put方式从前端传送过来的请求