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This article will explain in detail the common annotations of springmvc and the example analysis of operation input parameters. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Common annotations for springmvc. The parameter @ RequestParam is passed in for operation.

It is generally used to specify jsp parameter names and background method parameters, corresponding to

/ * * value=name when the parameters of jsp and the parameters on the method do not match, you can specify that * required () default true; default true must pass * * / public String testRequestParam (@ RequestParam (name = "name", required = false) String username) {System.out.println ("executed."); System.out.println (username); return "success";} testRequestParam

No parameters are passed, required () is set to false, and the method has parameters.

test

@ RequestBody

It is generally used to obtain the method body of the post request. The jsp parameter format is a key-value pair, that is, key-value.

This comment is not suitable for get requests and is generally used for post requests, such as form submission

If you want to use it for get requests, you need to

@ RequestBody (required = false)

Otherwise, an error is reported, and the method parameter is null.

@ RequestMapping (path = "testRequestBody") public String testRequestBody (@ RequestBody (required = false) String body) {System.out.println ("executed."); System.out.println (body); return "success";} user name:

Password:

test

@ PathVariable

URL placeholder, restful style, pass parameter format url address after / 10

Restful request method: get,post,put with comments @ RequestMapping sets the request method

@ RequestMapping (path = "testPathVariable/ {sid}", method = RequestMethod.GET) @ RequestMapping (path = "testPathVariable/ {sid}", method = RequestMethod.GET) / * * {sid} means that the URL placeholder * boolean required () default true; default parameter must pass * / public String testPathVariable (@ PathVariable ("sid") String id) {System.out.println ("executed.") System.out.println (id); return "success";} testPathVariable

You can download the postman client and simulate different ways of sending requests

Test:

@ RequestHeader

It is not commonly used to get some attribute values of the request header, such as browser type, version, etc.

@ RequestMapping (path = "testRequestHeader", method = RequestMethod.GET) / * get some attribute values of the request header, such as browser type, version, etc. / public String testRequestHeader (@ RequestHeader (value = "Accept") String head) {System.out.println ("executed."); System.out.println (head); return "success";} testRequestHeader

@ CookieValue

Get the value of JSESSIONID

@ RequestMapping (path = "testCookieValue", method = RequestMethod.GET) public String testCookieValue (@ CookieValue (value = "JSESSIONID") String JSESSIONID) {System.out.println ("executed."); System.out.println (JSESSIONID); return "success";} testCookieValue

@ ModelAttribute

The data used for encapsulation does not fully complete the data, or check scenarios such as encapsulated data

Can act on methods and parameters

The modification method, the method input parameter needs to be the same parameter type as the controller method, this method takes precedence over the controller, and the classification has return value and no return value.

If there is a return value, the return value of the method is the same as the input parameter of the controller

If there is no return value, the parameter of the method is not only the same as the input parameter of the controller, but also needs to add a map type parameter map.

Example:

The method of annotation modification is the return value writing method.

@ RequestMapping (path = "testModelAttribute") public String testModelAttribute (User user) {System.out.println ("executed."); System.out.println (user); return "success" } @ ModelAttribute / / modifier method, which takes precedence over the execution of public User showUser (User user) {/ * simulates the incomplete data encapsulated by user transmitted by jsp before the controller, and returns the full user object * / user.setBirthday (new Date ()) by querying the corresponding information of the database by name; return user;} user name:

Age:

The method of annotation modification has no return value.

@ RequestMapping (path = "testModelAttribute") public String testModelAttribute (@ ModelAttribute ("key") User user) {System.out.println ("executed."); System.out.println (user); return "success" } @ ModelAttribute / / modifier method, which takes precedence over the execution of public void showUser (User user, Map userMap) {/ * simulates the incomplete data encapsulated by user transmitted by jsp, and returns full user object * / user.setBirthday (new Date ()); userMap.put ("key", user);} by querying the corresponding information of the database by name.

test

@ SessionAttributes

Annotations can only act on classes and are used to access data to session domain objects to achieve method data sharing.

Implementation: copy data from the request domain object to the session domain

/ * * @ Date 2:05 on 2019-9-12 * by mocar * / @ Controller@RequestMapping (path = "/ anno") @ SessionAttributes (names = {"msg"}) / / copy to session domain object public class annoController {@ session ("/ setRequest") / / save to public String setRequest (ModelMap modelMap) {System.out.println ("setRequest."); modelMap.addAttribute ("msg", "session") / / go to request domain object to store the value return "success";} @ RequestMapping ("/ getSession") / / get public String getSession (ModelMap modelMap) {System.out.println ("getSession."); Object msg = modelMap.get ("msg"); System.out.println (msg.toString ()); return "success" } @ RequestMapping ("/ delSession") / / Delete public String delSession (SessionStatus sessionStatus,ModelMap modelMap) {System.out.println ("delSession."); sessionStatus.setComplete (); Object msg = modelMap.get ("msg"); System.out.println (msg.toString ()); return "success";}}

Jsp:

SetRequest

GetSession

DelSession

The success.jsp setting does not ignore EL expressions and displays session domain data

Quick start success ${sessionScope}

Setsession

Getsession

Delsession

This is the end of the example analysis of the common annotations and operation parameters of springmvc. I hope the above content can be helpful to you and learn more. If you think the article is good, you can share it for more people to see.

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