Spring MVC @RequestParam (5)

Case to illustrate

1 @RequestMapping ("User/add") publicstring Add (@RequestParam ("name") of string name,int age ) {4 System.out.println (name+ "," + Age);  Return "Hello";  6}         

Test 1

When we request the path to: http://localhost:8080/springmvc-1/user/add?name=caoyc&age=18

Output Result: caoyc,18

Test 2

When I request the path to: http://localhost:8080/springmvc-1/user/add?age=18

Output: An exception occurred. It means you have to have this parameter.

Solution: Add a required=false in the @requestparam tag to indicate that the property is not required

1 @RequestParam (value= "name", required=false)

Output Result: null,18

Test 3

When I request the path to: Http://localhost:8080/springmvc-1/user/add?name=caoyc

The same exception appears above

Then according to the method set above

1 @RequestParam (value= "age", required=int age

The result runs again. or throw an exception

It's very clear here, probably meaning that you can't say a null value is assigned to age. Package type should be used

Then we change the code to this:

1 @RequestParam (value= "age", required=false) Integer age

Result correct output: caoyc,null

There is another way to change this: Specify a default value for the parameter

1 @RequestParam (value= "age", required=int age

Result output: caoyc,0

"Summary" corresponds to the parameters of the @requestparam basic type we'd better use the packing type.

and a note of acquaintance.@RequestHeader. Use the same way as @requestparam. It's not a long explanation here.

Spring MVC @RequestParam (5)