What are the commonly used annotation tags in spring?

Spring commonly used annotation tags are: 1. "@Controller" tag; 2. "@RequestMapping" tag; 3. "@PathVariable" tag; 4. "@ModelAttribute" tag; 5. "@SessionAttributes" Tags and more.

Commonly used annotation tags in spring include: @Controller means to include the annotated class into the spring container, @RequestMapping is an annotation used to handle emergency address mapping, and @PathVariable Wait

spring common annotation tags

1, @Controller

corresponds to the Bean of the presentation layer, which is Action. Incorporate classes marked with this annotation into the spring container for management

2. @RequestMapping

RequestMapping is an annotation used to handle request address mapping and can be used for classes or method. Used on a class, it means that all methods in the class that respond to requests use this address as the parent path.

3, @Resource and @Autowired

@Resource and @Autowired are used for bean injection. In fact, @Resource is not an annotation of Spring. The package is javax.annotation.Resource and needs to be imported, but Spring supports the injection of this annotation.

4, @ModelAttribute and @SessionAttributes

represents: before calling all methods of the Controller, execute this @ModelAttribute method first, which can be used for annotations and methods In the parameters, you can apply this @ModelAttribute attribute to BaseController. All Controllers inherit BaseController, so that when calling the Controller, the @ModelAttribute method is executed first. @SessionAttributes puts the value into the session scope and writes it on the class.

5, @PathVariable

is used to map the template variables in the request URL to the parameters of the function processing method, that is, take out the variables in the uri template as parameters.

6, @requestParam

@requestParam is mainly used to obtain parameters in the SpringMVC background control layer. A similar one is request.getParameter("name"), which has three Commonly used parameters: defaultValue = "0", required = false, value = "isApp"; defaultValue means setting the default value, required is a boolean setting whether it is a parameter that must be passed in, and the value value indicates the type of parameters that are accepted. .

7, @ResponseBody

Function: This annotation is used to convert the object returned by the Controller method into the specified format through the appropriate HttpMessageConverter, and then writes it to the Response The body data area of ​​the object.

Usage timing: Use it when the returned data is not a page with html tags, but data in some other format (such as json, xml, etc.);

8, @Component

is equivalent to a general annotation, used when you don’t know which layer some classes belong to, but it is not recommended.

9. @Repository

is used to annotate the dao layer and annotate it on the daoImpl class.

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