# 1 环境
SpringBoot 2.7.6Java8
# 2 正文
首先我们在 Controller 层的方法参数中添加一个 @Email 的注解用于校验单个参数是否为合法的邮箱格式。然后在 Controller 类上添加 @Validated 注解，让 Springboot 进行 ** 参数校验。** 那么 Sprinboot 是如何完成参数校验的呢？这里就以 @Email 注解为例。
# 2.1 找到注解的处理器
进入 @Email 的源代码之后，使用 Ctrl + 鼠标左键 即可查看该注解的所有用法，在所有用法里可以看见一个类： EmailValidator ，从命名和该类所在的包可以断定： org.hibernate.validator.internal.constraintvalidators.bv.EmailValidator 即为校验被 @Email 所标注的参数的。
于是我们在其 isValid() 中打个断点，并调试启动本项目。
# 2.2 调用接口，开始 Debug
从 doDispatch() 到校验参数的方法栈如图。
这是调用没有方法校验的接口时的方法栈信息。通过把两次调用不同接口的线程转储日志存放到文件中后进行对比（文件会放最后），如下图：
可以看到两者的栈日志是从 org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:xxx) 开始的，两者的区别如下图：
步入
步入
画饼结束，看不懂。总结：
- 参数校验的方式是通过 AOP 切面
# 附件
"http-nio-7476-exec-1@8561" 守护进程 prio=5 tid=0x43 nid=NA runnable | |
java.lang.Thread.State: RUNNABLE | |
at com.sgqn.clubonline.web.controller.UserController.register(UserController.java:23) | |
at com.sgqn.clubonline.web.controller.UserController$$FastClassBySpringCGLIB$$175fa3ea.invoke(<generated>:-1) | |
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:793) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:89) | |
at com.sgqn.clubonline.web.aspect.GlobalRequestLoggerAspect.around(GlobalRequestLoggerAspect.java:40) | |
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) | |
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) | |
at java.lang.reflect.Method.invoke(Method.java:498) | |
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:634) | |
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:624) | |
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:72) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) | |
at com.sgqn.clubonline.web.controller.UserController$$EnhancerBySpringCGLIB$$b508e7de.register(<generated>:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) | |
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) | |
at java.lang.reflect.Method.invoke(Method.java:498) | |
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) | |
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) | |
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) | |
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) | |
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) | |
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) | |
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1071) |
"http-nio-7476-exec-3@8562" 守护进程 prio=5 tid=0x45 nid=NA runnable | |
java.lang.Thread.State: RUNNABLE | |
at org.hibernate.validator.internal.constraintvalidators.bv.EmailValidator.isValid(EmailValidator.java:55) | |
at org.hibernate.validator.internal.constraintvalidators.bv.EmailValidator.isValid(EmailValidator.java:26) | |
at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateSingleConstraint(ConstraintTree.java:180) | |
at org.hibernate.validator.internal.engine.constraintvalidation.SimpleConstraintTree.validateConstraints(SimpleConstraintTree.java:62) | |
at org.hibernate.validator.internal.engine.constraintvalidation.ConstraintTree.validateConstraints(ConstraintTree.java:75) | |
at org.hibernate.validator.internal.metadata.core.MetaConstraint.doValidateConstraint(MetaConstraint.java:130) | |
at org.hibernate.validator.internal.metadata.core.MetaConstraint.validateConstraint(MetaConstraint.java:123) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateMetaConstraint(ValidatorImpl.java:555) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateMetaConstraints(ValidatorImpl.java:537) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateParametersForSingleGroup(ValidatorImpl.java:991) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateParametersForGroup(ValidatorImpl.java:932) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateParametersInContext(ValidatorImpl.java:863) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateParameters(ValidatorImpl.java:283) | |
at org.hibernate.validator.internal.engine.ValidatorImpl.validateParameters(ValidatorImpl.java:235) | |
at org.springframework.validation.beanvalidation.MethodValidationInterceptor.invoke(MethodValidationInterceptor.java:110) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:89) | |
at com.sgqn.clubonline.web.aspect.GlobalRequestLoggerAspect.around(GlobalRequestLoggerAspect.java:40) | |
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) | |
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) | |
at java.lang.reflect.Method.invoke(Method.java:498) | |
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:634) | |
at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:624) | |
at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:72) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) | |
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) | |
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:763) | |
at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:708) | |
at com.sgqn.clubonline.web.controller.PermissionController$$EnhancerBySpringCGLIB$$2fb37eaa.captcha(<generated>:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:-1) | |
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) | |
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) | |
at java.lang.reflect.Method.invoke(Method.java:498) | |
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) | |
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150) | |
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117) | |
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895) | |
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808) | |
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) | |
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1071) |
