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@RequestParam

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您可以使用@RequestParam注解绑定 Servlet 请求参数（即 查询参数或表单数据）添加到控制器中的方法参数。spring-doc.cadn.net.cn

以下示例显示了如何执行此作：spring-doc.cadn.net.cn

@Controller
@RequestMapping("/pets")
public class EditPetForm {

	// ...

	@GetMapping
	public String setupForm(@RequestParam("petId") int petId, Model model) { (1)
		Pet pet = this.clinic.loadPet(petId);
		model.addAttribute("pet", pet);
		return "petForm";
	}

	// ...

}
1 用@RequestParam绑定petId. 
import org.springframework.ui.set

@Controller
@RequestMapping("/pets")
class EditPetForm {

	// ...

	@GetMapping
	fun setupForm(@RequestParam("petId") petId: Int, model: Model): String { (1)
		val pet = this.clinic.loadPet(petId);
		model["pet"] = pet
		return "petForm"
	}

	// ...

}
1 Using @RequestParam to bind petId.

By default, method parameters that use this annotation are required, but you can specify that a method parameter is optional by setting the @RequestParam annotation’s required flag to false or by declaring the argument with a java.util.Optional wrapper.spring-doc.cadn.net.cn

Type conversion is automatically applied if the target method parameter type is not String. See Type Conversion.spring-doc.cadn.net.cn

Declaring the argument type as an array or list allows for resolving multiple parameter values for the same parameter name.spring-doc.cadn.net.cn

When an @RequestParam annotation is declared as a Map<String, String> or MultiValueMap<String, String>, without a parameter name specified in the annotation, then the map is populated with the request parameter values for each given parameter name. The following example shows how to do so with form data processing:spring-doc.cadn.net.cn

@Controller
@RequestMapping("/pets")
class EditPetForm {

	// ...

	@PostMapping(path = "/process", consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
	public String processForm(@RequestParam MultiValueMap<String, String> params) {
		// ...
	}

	// ...
}
@Controller
@RequestMapping("/pets")
class EditPetForm {

	// ...

	@PostMapping("/process", consumes = [MediaType.APPLICATION_FORM_URLENCODED_VALUE])
	fun processForm(@RequestParam params: MultiValueMap<String, String>): String {
		// ...
	}

	// ...

}

Note that use of @RequestParam is optional (for example, to set its attributes). By default, any argument that is a simple value type (as determined by BeanUtils#isSimpleProperty) and is not resolved by any other argument resolver, is treated as if it were annotated with @RequestParam.spring-doc.cadn.net.cn