驗證BigDecimal字段

Question

我想驗證我的項目中使用spring mvc + jpa hibernate的BigDecimal字段。字段名稱爲： private BigDecimal totalAreaInAcres;

輸入字段中的jsp是：

<p> 
<label for="totalAreaInAcres">Total Area in acres</label> 
<form:input path="totalAreaInAcres"/> 
<form:errors path="totalAreaInAcres" cssClass="error"></form:errors> 
</p> 

現在，這個輸入域的驗證服務器使用端驗證：

BigDecimal area=layout.getTotalAreaInAcres(); 

System.out.println("area="+area); 

String areaInString=area.toString(); 
System.out.println("area in string="+areaInString); 

if(areaInString==null) 
{ 
    ValidationUtils.rejectIfEmptyOrWhitespace(errors, "totalAreaInAcres", 
      "field.name.empty", 
      "Enter Total area in acres"); 
} 

該字段應在進入任何字符顯示錯誤消息。當我輸入數字時，它已成功添加到數據庫，但是我添加了字符它的拋出NullPointerException。這裏是我的堆棧跟蹤：

SEVERE: Servlet.service() for servlet [Spring MVC Dispatcher Servlet] in context with  path [/TalentCity] threw exception [Request processing failed; nested exception is java.lang.NullPointerException] with root cause 
java.lang.NullPointerException 
at  in.corasent.talentcity.utils.AddLayoutValidator.validateLayout(AddLayoutValidator.java:40) 
at in.corasent.talentcity.web.adminControllers.AddLayout.postLayoutDetails(AddLayout.java:57) 
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
at java.lang.reflect.Method.invoke(Method.java:616) 
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213) 
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126) 
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96) 
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617) 
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578) 
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80) 
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) 
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) 
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) 
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:343) 
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109) 
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:188) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:109) 
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:355) 
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:149) 
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) 
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) 
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407) 
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002) 
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585) 
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310) 
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) 
at java.lang.Thread.run(Thread.java:679) 

我也用註釋：

@NumberFormat(style=Style.NUMBER) 
@Pattern(regexp="[0-9].[0-9]") 
private BigDecimal totalAreaInAcres; 

，但沒有運氣和它拋出同樣的錯誤。任何人都可以讓我知道如何驗證，以避免輸入字段中的字符或在輸入字符時顯示錯誤消息。

謝謝。

Answer 1

東西是在40行，我不知道它是什麼AddLayoutValidator空，但我從你的代碼，你試試它的驗證前使用的area值看。由於它是BigDecimal，如果您沒有發佈數字，它只能爲空。

Answer 2

您使用了「@NumberFormat（style = Style.NUMBER）」註釋，當您輸入除數字以外的任何字符時，它將引發異常。