1 root cause
 2 
 3 org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.hs.model.StudentModel]: No default constructor found; nested exception is java.lang.NoSuchMethodException: com.hs.model.StudentModel.<init>()
 4     org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:108)
 
 5     org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:136)
 6     org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:81)
 7     org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:101)
 
 8     org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)
 9     org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:162)
10     org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:123)
 
11     org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
12     org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
13     org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
14     org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
15     org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
16     org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
17     org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
18     org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838)
19     javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
20     org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
21     javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
22     org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
23     org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
24     org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
25 root cause
26 
27 java.lang.NoSuchMethodException: com.hs.model.StudentModel.<init>()
28     java.lang.Class.getConstructor0(Class.java:2902)
29     java.lang.Class.getDeclaredConstructor(Class.java:2066)
30     org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:105)
31     org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:136)
32     org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:81)
33     org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:101)
34     org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)
35     org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:162)
36     org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:123)
37     org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
38     org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
39     org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:686)
40     org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
41     org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
42     org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
43     org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:936)
44     org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:838)
45     javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
46     org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:812)
47     javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
48     org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
49     org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
50     org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

有人說是實體類中沒有無參構造方法

 https://blog.csdn.net/zhengsaisai/article/details/79626895