Doraemon teach you forwarded and redirect page

Hi, my name is Gao Guo~

spring MVC view

• • 1. Simple example
  • 2. Forward request forwarding view
  • 3. redirect redirect view
  • 4. The difference between redirection and forwarding
  • • 4.1 Retweet
    • 4.2 Redirects
    • 4.3 Comparison

1. Simple example

In the controller methods of Spring MVC, the common return types are ModelAndView, String, void.The ModelAndView type can add Model data and specify the view; the return value of the String type can jump to try, but cannot carry data; the void type is mainly used in asynchronous requests, only returning data, not jumping to the view.

Because the ModelAndView type fails to realize the decoupling between the data and the view, usually the return type is String, so when using String as the return value type, how to bring the data into the view page?

This requires the Model parameter type to achieve, through this parameter type, you can add the information that needs to be displayed in the view.

The controller method is as follows:

@RequestMapping("/modelTest")public String modelTest(Model model){model.addAttribute("msg","This is a Spring MVC program!");return "success";}

In addition to returning the view page of the above code, the String type can also perform redirection and request forwarding

2. forward request forwarding view

When sending a request, forward: can be used to realize the forwarding function
forward: can also jump from one request to another request

The controller method is as follows:

@RequestMapping("/forwardTest")public String forwardTest(){return "forward:/modelTest";}

Note: When the view name set in the controller method is prefixed with "forward:", the InternalResourceView view is created. The view name at this time will not be parsed by the view resolver configured in the SpringMVC configuration file, butThe prefix "forward:" will be removed, and the remaining part will be used as the final path to jump through forwarding.

3. redirect redirect view

redirect : The redirected path

The controller method is as follows:

@RequestMapping("/redirectTest")public String redirectTest(){return "redirect:/modelTest";}

Note: When the view name set in the controller method is prefixed with "redirect:", a RedirectView view is created. The view name at this time will not be parsed by the view resolver configured in the SpringMVC configuration file, butThe prefix "redirect:" will be removed, and the remaining part will be redirected as the final path.

4. The difference between redirection and forwarding

4.1 Retweet

The page is jumped by the server, and the client does not need to re-send the request:
Features are as follows:
1. The request in the address bar will not change, and the address of the first request is displayed
2. The number of requests, there is only one request
3. The data in the request domain will not be lost
4. The root directory: localhost:8080/project address/, which contains the access address of the project

4.2 redirects

For page jumping on the browser side, two requests need to be sent (the first time is artificial, the second time is automatic)
The features are as follows:
1. The address in the address bar changes, display the address of the latest request
2. The number of requests: 2 times
3. The data in the request domain will be lost because it is a different request
4. The root directory: localhost:8080/ does not contain itemsName of

4.3 Comparison

Difference

Forward

Redirect

root directory

Include project access address

No project access address

Address bar

No change

Changes will occur

Jump location

Server side

Browser side

Data in the request field

Not lost

will be lost

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