Spring MVC@RequestParam DefaultValue未为带有emptyvalue的参数设置[重复]

Question

 http://india.webinc.in:8080/caseManagement/caseView?lock=false&caseId= 

@RequestMapping(value = "/caseView", method = RequestMethod.GET)
public String caseView(
final HttpServletRequest request,   
@RequestParam(value = "caseId", defaultValue = "-1") final Integer caseId
){
System.out.println("request.getparameter(caseId)::" + request.getParameter("caseId"));
System.out.println("@RequestParam caseId::" + caseId);
if (caseId != -1) {
//do something
} else {
//do something else
} 
} 

request.getparameter(caseId)::
@RequestParam caseId::null
java.lang.NullPointerException

Answer 1

现在，根据doc的默认值可以用作当请求参数值为空时的后退，那么empty caseId没有设置为-1的原因是什么？

似乎只要caseid参数存在于请求的查询参数中，它就被视为提供了一个值“”，从而得到您所遇到的结果。的

提供的或空的