1,基本使用方法
Spring的@ExceptionHandler可以用来统一处理方法抛出的异常,比如这样:
@ExceptionHandler()
public String handleExeption2(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:默认";
return resultStr;
}
当我们使用这个@ExceptionHandler注解时,我们需要定义一个异常的处理方法,比如上面的handleExeption2()方法,给这个方法加上@ExceptionHandler注解,这个方法就会处理类中其他方法(被@RequestMapping注解)抛出的异常。
2,注解的参数
@ExceptionHandler注解中可以添加参数,参数是某个异常类的class,代表这个方法专门处理该类异常,比如这样:
@ExceptionHandler(NumberFormatException.class)
public String handleExeption(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:NumberFormatException";
return resultStr;
}
此时注解的参数是NumberFormatException.class,表示只有方法抛出NumberFormatException时,才会调用该方法。
3,就近原则
当异常发生时,Spring会选择最接近抛出异常的处理方法。
比如之前提到的NumberFormatException,这个异常有父类RuntimeException,RuntimeException还有父类Exception,如果我们分别定义异常处理方法,@ExceptionHandler分别使用这三个异常作为参数,比如这样:
@ExceptionHandler(NumberFormatException.class)
public String handleExeption(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:NumberFormatException";
return resultStr;
}
@ExceptionHandler()
public String handleExeption2(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:默认";
return resultStr;
}
@ExceptionHandler(RuntimeException.class)
public String handleExeption3(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:RuntimeException";
return resultStr;
}
那么,当代码抛出NumberFormatException时,调用的方法将是注解参数NumberFormatException.class的方法,也就是handleExeption(),而当代码抛出IndexOutOfBoundsException时,调用的方法将是注解参数RuntimeException的方法,也就是handleExeption3()。
4,注解方法的返回值
标识了@ExceptionHandler注解的方法,返回值类型和标识了@RequestMapping的方法是统一的,可参见@RequestMapping的说明,比如默认返回Spring的ModelAndView对象,也可以返回String,这时的String是ModelAndView的路径,而不是字符串本身。
有些情况下我们会给标识了@RequestMapping的方法添加@ResponseBody,比如使用Ajax的场景,直接返回字符串,异常处理类也可以如此操作,添加@ResponseBody注解后,可以直接返回字符串,比如这样:
@ExceptionHandler(NumberFormatException.class)
@ResponseBody
public String handleExeption(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:NumberFormatException";
return resultStr;
}
这样的操作可以在执行完方法后直接返回字符串本身。
5,错误的操作
使用@ExceptionHandler时尽量不要使用相同的注解参数。
如果我们定义两个处理相同异常的处理方法:
@ExceptionHandler(NumberFormatException.class)
@ResponseBody
public String handleExeption(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:NumberFormatException";
return resultStr;
}
@ExceptionHandler(NumberFormatException.class)
@ResponseBody
public String handleExeption2(Exception ex) {
System.out.println("抛异常了:" + ex);
ex.printStackTrace();
String resultStr = "异常:默认";
return resultStr;
}
两个方法都处理NumberFormatException,这种定义方式编译可以通过,而当NumberFormatException真正被抛出时,Spring会给我们报错:
java.lang.IllegalStateException: Ambiguous @ExceptionHandler method mapped for [class java.lang.NumberFormatException]: {public java.lang.String TestController.handleExeption(java.lang.Exception), public java.lang.String TestController.handleExeption2(java.lang.Exception)}
at org.springframework.web.method.annotation.ExceptionHandlerMethodResolver.addExceptionMapping(ExceptionHandlerMethodResolver.java:102) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.method.annotation.ExceptionHandlerMethodResolver.<init>(ExceptionHandlerMethodResolver.java:66) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.getExceptionHandlerMethod(ExceptionHandlerExceptionResolver.java:458) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver.doResolveHandlerMethodException(ExceptionHandlerExceptionResolver.java:378) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionResolver.doResolveException(AbstractHandlerMethodExceptionResolver.java:61) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.handler.AbstractHandlerExceptionResolver.resolveException(AbstractHandlerExceptionResolver.java:140) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.handler.HandlerExceptionResolverComposite.resolveException(HandlerExceptionResolverComposite.java:78) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processHandlerException(DispatcherServlet.java:1255) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1062) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1008) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) ~[javax.servlet-api-3.1.0.jar:3.1.0]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851) ~[spring-webmvc-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[javax.servlet-api-3.1.0.jar:3.1.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-5.0.5.RELEASE.jar:5.0.5.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-embed-core-8.5.29.jar:8.5.29]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.29.jar:8.5.29]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_172]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_172]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.29.jar:8.5.29]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_172]
以上
原文链接:https://blog.csdn.net/lkforce/article/details/98494922
标签:8.5,java,jar,ExceptionHandler,29,org,RELEASE,注解 From: https://www.cnblogs.com/jiuchenchen/p/17407530.html