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The code used can be found here

5, RequestMapping

@The RequestMapping annotation is used to map URLs to a controller class or a specific handler method. Can be used on classes or methods. Used on a class to indicate that all methods in the class that respond to requests take this address as the parent path.

• Annotations on classes and methods

  (you can access the class first and then the method)

• Annotation class only

  @Controller
  public class ControllerTest3 {
      @RequestMapping("/sss")
      public String test(){
          return "test";
      }
  }

Usually write it directly

6, RestFul style

concept

Restful is a style of resource location and resource operation. It's not a standard or agreement, it's just a style. The software designed based on this style can be more concise, more hierarchical, and easier to implement caching and other mechanisms.

Modify the item to find the person you need

function

Resources: all things on the Internet can be abstracted as resources

Resource operation: use POST, DELETE, PUT and GET to operate resources using different methods.

Add, delete, modify and query respectively.

• Operate resources in the traditional way: achieve different effects through different parameters! Single method, post and get

​ http://127.0.0.1/item/queryItem.action?id=1 Query, GET

​ http://127.0.0.1/item/saveItem.action New, POST

​ http://127.0.0.1/item/updateItem.action Update, POST

​ http://127.0.0.1/item/deleteItem.action?id=1 Delete, GET or POST

• Using RESTful operation resources: different effects can be achieved through different request methods! As follows: the request address is the same, but the function can be different!

​ http://127.0.0.1/item/1 Query, GET

​ http://127.0.0.1/item New, POST

​ http://127.0.0.1/item Update, PUT

​ http://127.0.0.1/item/1 DELETE

Learning test

In Spring MVC, you can use the @ PathVariable annotation to bind the value of the method parameter to a URI template variable.

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class RestFulController {
    //The original method: localhost: 8080 / add? A = 1 & B = 2
    @RequestMapping("/add")
    public String test(int a, int b, Model model){
        int res = a + b;
        model.addAttribute("msg","The result is" + res);
        return "test";
    }

    //RestFul: localhost:8080/add2/1/2
    @RequestMapping("/add2/{a}/{b}")
    public String test1(@PathVariable int a,@PathVariable int b, Model model){
        int res = a + b;
        model.addAttribute("msg","The result is" + res);
        return "test";
    }
}

thinking Test : send use road path change amount of good place ？ \textcolor{orange} {thinking: the benefits of using path variables?} Think: what are the benefits of using path variables?

• Make the path more concise;
• Efficient and safe
• It is more convenient to obtain parameters, and the framework will automatically perform type conversion.
• Access parameters can be constrained by the type of path variables. If the types are different, the corresponding request method cannot be accessed. For example, if the access path here is / commit/1/a, the path does not match the method, rather than parameter conversion failure.

Use the method property to specify the request type

It is used to constrain the type of request and narrow the request range. Specify the type of request predicate, such as GET, POST, HEAD, OPTIONS, PUT, PATCH, DELETE, TRACE, etc

• post

  //The mapped access path must be a POST request
  @RequestMapping(value = "/add/{a}/{b}",method = {RequestMethod.POST})
      public String test3(@PathVariable int a,@PathVariable int b, Model model){
          int res = a + b;
          model.addAttribute("msg","The result is" + res);
          return "test";
      }
  

  It is OK to jump from this jsp page through the submit button

  

• We use the browser address bar to access. By default, it is a Get request, and an error 405 will be reported:

  If you change POST to GET, it is normal;

  //Map access path, must be a Get request
  @RequestMapping(value = "/add/{a}/{b}",method = {RequestMethod.GET})
      public String test2(@PathVariable int a,@PathVariable int b, Model model){
          int res = a + b;
          model.addAttribute("msg","The result is" + res);
          return "test";
      }
  

Summary:

The @ RequestMapping annotation of Spring MVC can handle HTTP requests, such as GET, PUT, POST, DELETE and PATCH.

All address bar requests will be of HTTP GET type by default.

Method level annotation variants are as follows: combined annotation

@GetMapping
@PostMapping
@PutMapping
@DeleteMapping
@PatchMapping

@GetMapping is a combined annotation, which is often used!

It acts as a shortcut to @ RequestMapping(method =RequestMethod.GET).