Spring框架注解

痛定思痛。 2022-03-17 01:14 210阅读 0赞

## 获取配置信息 ##

> spring-beans模块【spring-beans-4.3.12.RELEASE.jar】

*  @Value注解，获取配置文件中的值

@Value("${up_excel_path}")
    private String excelPath;
    @Value("${categoryCode}")
    private String categoryCode;

*  源码

@Target({ ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface Value { 
    
    	/** * The actual value expression: e.g. "#{systemProperties.myProp}". */
    	String value();
    
    }

## 常用注解 ##

> 源码在Spring核心模块之一Context【**spring-context-4.3.12.RELEASE.jar**】中

*  Component 注解

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface Component { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected * component. * @return the suggested component name, if any */
    	String value() default "";
    
    }

*  Controller 注解

@Target({ ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Component
    public @interface Controller { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected component. * @return the suggested component name, if any */
    	String value() default "";
    
    }

*  Repository 注解

@Target({ ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Component
    public @interface Repository { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected component. * @return the suggested component name, if any */
    	String value() default "";
    
    }

*  Service 注解

@Target({ ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Component
    public @interface Service { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected component. * @return the suggested component name, if any */
    	String value() default "";
    
    }

## 事务相关注解 ##

> 源码在Spring【**spring-tx-4.3.12.RELEASE.jar**】中

*  [Transactional 注解][Transactional]

@Target({ ElementType.METHOD, ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Inherited
    @Documented
    public @interface Transactional { 
    
    	@AliasFor("transactionManager")
    	String value() default "";
    
    	@AliasFor("value")
    	String transactionManager() default "";
    
    	Propagation propagation() default Propagation.REQUIRED;
    
    	Isolation isolation() default Isolation.DEFAULT;
    
    	int timeout() default TransactionDefinition.TIMEOUT_DEFAULT;
    
    	boolean readOnly() default false;
    
    	Class<? extends Throwable>[] rollbackFor() default { };
    
    	String[] rollbackForClassName() default { };
    
    	Class<? extends Throwable>[] noRollbackFor() default { };
    
    	String[] noRollbackForClassName() default { };
    
    }

## WEB相关注解 ##

> 源码在Spring的WEB模块【**spring-web-4.3.12.RELEASE.jar**】中

*  ResponseBody 注解

@Target({ ElementType.TYPE, ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface ResponseBody { 
    
    }

*  RestController 注解

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Controller
    @ResponseBody
    public @interface RestController { 
    
    	/** * The value may indicate a suggestion for a logical component name, * to be turned into a Spring bean in case of an autodetected component. * @return the suggested component name, if any * @since 4.0.1 */
    	String value() default "";
    
    }

*  PathVariable 注解

@Target(ElementType.PARAMETER)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface PathVariable { 
    
    	/** * Alias for {@link #name}. */
    	@AliasFor("name")
    	String value() default "";
    
    	/** * The name of the path variable to bind to. * @since 4.3.3 */
    	@AliasFor("value")
    	String name() default "";
    
    	/** * Whether the path variable is required. * <p>Defaults to {@code true}, leading to an exception being thrown if the path * variable is missing in the incoming request. Switch this to {@code false} if * you prefer a {@code null} or Java 8 {@code java.util.Optional} in this case. * e.g. on a {@code ModelAttribute} method which serves for different requests. * @since 4.3.3 */
    	boolean required() default true;
    
    }

*  RequestParam 注解

@Target(ElementType.PARAMETER)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface RequestParam { 
    
    	/** * Alias for {@link #name}. */
    	@AliasFor("name")
    	String value() default "";
    
    	/** * The name of the request parameter to bind to. * @since 4.2 */
    	@AliasFor("value")
    	String name() default "";
    
    	/** * Whether the parameter is required. * <p>Defaults to {@code true}, leading to an exception being thrown * if the parameter is missing in the request. Switch this to * {@code false} if you prefer a {@code null} value if the parameter is * not present in the request. * <p>Alternatively, provide a {@link #defaultValue}, which implicitly * sets this flag to {@code false}. */
    	boolean required() default true;
    
    	/** * The default value to use as a fallback when the request parameter is * not provided or has an empty value. * <p>Supplying a default value implicitly sets {@link #required} to * {@code false}. */
    	String defaultValue() default ValueConstants.DEFAULT_NONE;
    
    }

## @Import注解 ##

@Import只能用在类上 ，@Import通过快速导入的方式实现把实例加入spring的IOC容器中

[Transactional]: https://www.cnblogs.com/yepei/p/4716112.html