Question

当我在这里阅读explanation时，我发现Spring可以自动将GET请求参数绑定到一个类型。以下是链接中的示例代码。

@Controller
@RequestMapping("/person")
public class PersonController {
        ...             
        @RequestMapping("/create")
        public String create(Person p) {
                //TODO: add Person to DAO
                return "person/show";
        }
}

有人能告诉我春天是怎么做到的吗？什么bean包含将参数转换为命令类型（Person类型）的逻辑？

Answer 1

诀窍在这里完成：org.springframework.web.method.annotation.ModelAttributeMethodProcessor#resolveArgument()

这是代码的摘录，它实际上将类绑定到值：

String name = ModelFactory.getNameForParameter(parameter);
//Here it determines the type of the parameter and creates an instance
Object attribute = (mavContainer.containsAttribute(name)) ?
            mavContainer.getModel().get(name) : createAttribute(name, parameter, binderFactory, request);

//Then it binds the parameters from the servlet to the previously created instance
WebDataBinder binder = binderFactory.createBinder(request, attribute, name);
if (binder.getTarget() != null) {
    bindRequestParameters(binder, request);
    validateIfApplicable(binder, parameter);
    if (binder.getBindingResult().hasErrors()) {
        if (isBindExceptionRequired(binder, parameter)) {
            throw new BindException(binder.getBindingResult());
        }
    }
}

Spring MVC默认GET请求参数绑定到命令类型

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