SpelEvaluationException: Eigenschaft oder Feld 'Benutzername' kann nicht auf Null

Question

mein Projekt basiert auf Springboot und Bootstrap, ich werde den Benutzernamen behalten, wenn eine Person mit Fehler einloggen, aber ich möchte nicht verwenden die ajax.so habe ich das thymelefleum verwendet, um die botschaft vom modell zu zeigen. hier ist mein Projekt Eingang:

@Configuration 
public class WebMvcConfigure extends WebMvcConfigurerAdapter { 

@Override 
public void addViewControllers(ViewControllerRegistry registry) { 
    ModelMap modelMap = new ModelMap(); 
    modelMap.addAttribute("user", new User()); 
    registry.addViewController("/").setViewName("pages/admin3/login_soft"); 
    registry.setOrder(Ordered.HIGHEST_PRECEDENCE); 
    super.addViewControllers(registry); 
    String os = System.getProperty("os.name"); 
    if(os.toLowerCase().startsWith("win")){ 
     Browse("http://localhost:8085"); 
    } 

} 

und dies ist mein Controller:

@RestController 
@RequestMapping("user") 
public class UserController extends BaseController { 

@Autowired 
UserRepository userRepository; 

@RequestMapping(value = "/login", method = RequestMethod.POST) 
public ModelAndView login(@ModelAttribute User user) { 
    User byUsernameOrEmail = 
    userRepository.findUserByUsernameOrEmail(user.getUsername(), 
    user.getUsername()); 

    ModelAndView mv = new ModelAndView(); 
    mv.addObject("user", user); 
    if (CommonUtils.isEmpty(byUsernameOrEmail)) { 
     mv.addObject("message", ExceptionMsg.LoginNameNotExist.getMsg()); 
     mv.setViewName("redirect:/"); 
     return mv; 
    } else if (!PasswordUtils.getMD5(user.getPassword() + 
      byUsernameOrEmail.getSalt()) 
      .equals(byUsernameOrEmail.getPassword())) { 
    mv.addObject("message",ExceptionMsg.LoginNameOrPassWordError.getMsg()); 
     mv.setViewName("redirect:/"); 
     return mv; 
    } 

    mv.setViewName("pages/admin3/login_soft"); 

    return mv; 
} 

und das ist mein html:

<form class="login-form" th:action="@{/user/login}" th:object="${user}" method="post" > 

       <h3 class="form-title">登录</h3> 
       <div class="alert alert-danger" th:if="${#httpServletRequest.getParameter('message')}"> 
        <button class="close" data-close="alert"></button> 
        <span th:text="${#httpServletRequest.getParameter('message')}"></span> 
       </div> 
       <div class="form-group"> 
        <!--ie8, ie9 does not support html5 placeholder, so we just show field title for that request.getCookies()--> 
        <label class="control-label visible-ie8 visible-ie9">Username</label> 
        <div class="input-icon"> 
         <i class="fa fa-user"></i> 
         <input class="form-control placeholder-no-fix" type="text" autocomplete="off" placeholder="用户名|邮箱" 
           name="username" th:value="${user.username}" /> 
        </div> 
       </div> 
       <div class="form-group"> 
        <label class="control-label visible-ie8 visible-ie9">Password</label> 
        <div class="input-icon"> 
         <i class="fa fa-lock"></i> 
         <input class="form-control placeholder-no-fix" type="password" autocomplete="off" placeholder="密码" name="password"/> 
        </div> 
       </div> 
       <div class="form-actions"> 
        <label class="checkbox"> 
        <input type="checkbox" name="remember" value="1"/> 记住密码 </label> 
        <button type="submit" class="btn blue pull-right"> 
        登录 <i class="m-icon-swapright m-icon-white"></i> 
        </button> 
       </div> 

     </form> 

, wenn ich das Projekt begann, zeigte sich, dass:

org.springframework.expression.spel.SpelEvaluationException: EL1007E:(pos 0): Property or field 'username' cannot be found on null 
      at org.springframework.expression.spel.ast.PropertyOrFieldReference.readProperty(PropertyOrFieldReference.java:220) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.ast.PropertyOrFieldReference.getValueInternal(PropertyOrFieldReference.java:94) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.ast.PropertyOrFieldReference.access$000(PropertyOrFieldReference.java:46) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.ast.PropertyOrFieldReference$AccessorLValue.getValue(PropertyOrFieldReference.java:375) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:88) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.ast.SpelNodeImpl.getValue(SpelNodeImpl.java:120) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:267) ~[spring-expression-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.thymeleaf.spring4.expression.SpelVariableExpressionEvaluator.evaluate(SpelVariableExpressionEvaluator.java:139) ~[thymeleaf-spring4-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.expression.VariableExpression.executeVariable(VariableExpression.java:154) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.expression.SimpleExpression.executeSimple(SimpleExpression.java:59) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.expression.Expression.execute(Expression.java:103) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.expression.Expression.execute(Expression.java:133) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.expression.Expression.execute(Expression.java:120) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.standard.processor.attr.AbstractStandardSingleAttributeModifierAttrProcessor.getTargetAttributeValue(AbstractStandardSingleAttributeModifierAttrProcessor.java:67) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.spring4.processor.attr.SpringValueAttrProcessor.getTargetAttributeValue(SpringValueAttrProcessor.java:71) ~[thymeleaf-spring4-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.processor.attr.AbstractSingleAttributeModifierAttrProcessor.getModifiedAttributeValues(AbstractSingleAttributeModifierAttrProcessor.java:59) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.processor.attr.AbstractAttributeModifierAttrProcessor.processAttribute(AbstractAttributeModifierAttrProcessor.java:62) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1017) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:972) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:695) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:668) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Node.processNode(Node.java:990) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.dom.Document.process(Document.java:93) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011) ~[thymeleaf-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335) ~[thymeleaf-spring4-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190) ~[thymeleaf-spring4-2.1.5.RELEASE.jar:2.1.5.RELEASE] 
      at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1257) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1037) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:980) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:89) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.4.RELEASE.jar:4.3.4.RELEASE] 
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:784) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:802) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1410) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_131] 
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_131] 
      at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.6.jar:8.5.6] 
      at java.lang.Thread.run(Thread.java:748) [na:1.8.0_131] 

Ich habe viele andere gesucht Fragen, sie vorgeschlagen, dass die [Benutzer] auf das Modell setzen, aber ich habe das getan, warum hat es immer noch diesen Fehler angezeigt? releated question

Answer 1

Sie verwenden Benutzer auch im th: Objektth:object="${user}"

Versuchen Sie das Benutzerobjekt durch etwas anderes und auch sicherstellen, dass die Umbenennung, dass das Objekt, das Sie zum Modell vorbei besiedelt richtig.

So etwas wie mv.addObject("userDetails", user); und dann in Ihrem html:

<input class="form-control placeholder-no-fix" type="text" autocomplete="off" placeholder="用户名|邮箱" name="username" th:value="${userDetails.username}"/>