SpringMVC注解分析01-RequestMapping

╰+攻爆jí腚メ 2022-08-14 04:59 133阅读 0赞

当你对某事疑惑的时候，特别是技术上的疑点，最好立即解决。

# 1、注解的结构 #

![Image 1][]![Center][]

# 2.元数据 #

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

Target表明该注解作用在方法上；

Retention表明该注解是在运行时起作用；RetentionPolicy 保留策略（SOURCE，）

@Target({ElementType.ANNOTATION_TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface Mapping {
    
    }

# 3.方法 #

/**
 	 * Assign a name to this mapping.
 	 * Supported at the type level as well as at the method level!
 	 * When used on both levels, a combined name is derived by concatenation
 	 * with "#" as separator.
 	 * @see org.springframework.web.servlet.mvc.method.annotation.MvcUriComponentsBuilder
 	 * @see org.springframework.web.servlet.handler.HandlerMethodMappingNamingStrategy
 	 */
 	String name() default "";

应用场景，在Controller类中的方法上加

@RequestMapping("/view")

代表以/view为路径的URL可以映射到该方法上。

/**
 	 * The HTTP request methods to map to, narrowing the primary mapping:
 	 * GET, POST, HEAD, OPTIONS, PUT, PATCH, DELETE, TRACE.
 	 * Supported at the type level as well as at the method level!
 	 * When used at the type level, all method-level mappings inherit
 	 * this HTTP method restriction (i.e. the type-level restriction
 	 * gets checked before the handler method is even resolved).
 	 * Supported for Servlet environments as well as Portlet 2.0 environments.
 	 */
 	RequestMethod[] method() default {};

用于设定http提交方式

/**
 	 * The parameters of the mapped request, narrowing the primary mapping.
 	 * Same format for any environment: a sequence of "myParam=myValue" style
 	 * expressions, with a request only mapped if each such parameter is found
 	 * to have the given value. Expressions can be negated by using the "!=" operator,
 	 * as in "myParam!=myValue". "myParam" style expressions are also supported,
 	 * with such parameters having to be present in the request (allowed to have
 	 * any value). Finally, "!myParam" style expressions indicate that the
 	 * specified parameter is not supposed to be present in the request.
 	 * Supported at the type level as well as at the method level!
 	 * When used at the type level, all method-level mappings inherit
 	 * this parameter restriction (i.e. the type-level restriction
 	 * gets checked before the handler method is even resolved).
 	 * In a Servlet environment, parameter mappings are considered as restrictions
 	 * that are enforced at the type level. The primary path mapping (i.e. the
 	 * specified URI value) still has to uniquely identify the target handler, with
 	 * parameter mappings simply expressing preconditions for invoking the handler.
 	 * In a Portlet environment, parameters are taken into account as mapping
 	 * differentiators, i.e. the primary portlet mode mapping plus the parameter
 	 * conditions uniquely identify the target handler. Different handlers may be
 	 * mapped onto the same portlet mode, as long as their parameter mappings differ.
 	 */
 	String[] params() default {};

接收请求发送的参数信息。

[Image 1]: 
[Center]: /images/20220731/a8225c272edd4043a9f8a10a204b3cc2.png