Spring Boot : 全局异常捕捉(三)

前言

在写 Spring Boot : 自动JSON转换和热部署(二) 时本来想把全局异常捕捉加上的,但是不知道为什么测试一直没成功.今天又看了下全局异常捕捉@ControllerAdvice 和 @ExceptionHandler 两个标签. 参考 : Spring3.2新注解@ControllerAdvice , 在spring加载bean的时候一定要把全局异常捕捉类加载进来,否则是不成功的.

目录

下面是反面教程 :

基于之前的写法创建MyDefaultExceptionHandler类:

package cn.milo.controllor;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 * Created by admin on 2017/6/25.
 */

@ControllerAdvice
public class MyDefaultExceptionHandler {
    @ExceptionHandler(value = Exception.class)
    //    @ExceptionHandler(value={RuntimeException.class,MyRuntimeException.class}) 指定具体要处理的异常
    //    @ExceptionHandler//处理所有异常
    @ResponseBody //在返回自定义相应类的情况下必须有，这是@ControllerAdvice注解的规定
    public String  exceptionHandler() {
        System.out.println("DefaultExceptionHandler.exceptionHandler()");
        return "DefaultExceptionHandler Running";
    }
}

在SampleController中添加 :

package cn.milo.controllor;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * Created by admin on 2017/6/25.
 */
@Controller
/*
@RestController is a stereotype annotation that combines @ResponseBody and @Controller.
意思是：
@RestController注解相当于@ResponseBody ＋ @Controller合在一起的作用。
 */
@EnableAutoConfiguration
public class SampleController {
    @RequestMapping("/demo10")
    public String demo104Exception() {
       int k = 1/0;
       return "1";
    }

/*
ExceptionHandler 不是一定在@ControllerAdvice 标注的类中才生效.如将注释放开,异常可以被捕捉.且捕捉顺序如下:

同一个异常被局部范围异常处理器和全局范围异常处理器同时覆盖，会选择小范围的局部范围处理器
同一个异常被小范围的异常类和大范围的异常处理器同时覆盖，会选择小范围的异常处理器

*/
//    @ExceptionHandler(Exception.class)
//    public void ExceptionHandler(){
//        System.out.println("捕捉到异常了.....");
//    }
}

请求 : http://localhost:8080/demo10 控制台信息如下 :

2017-06-28 18:27:18.207 ERROR 12536 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.ArithmeticException: / by zero] with root cause

java.lang.ArithmeticException: / by zero
    at cn.milo.controllor.SampleController.demo104Exception(SampleController.java:83) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_17]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_17]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_17]
    at java.lang.reflect.Method.invoke(Method.java:601) ~[na:1.7.0_17]
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:222) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:137) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:814) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:737) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:959) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:893) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:121) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.2.3.RELEASE.jar:4.2.3.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217) ~[tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_17]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_17]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.0.28.jar:8.0.28]
    at java.lang.Thread.run(Thread.java:722) [na:1.7.0_17]

说明异常根本没有被捕捉啊.分析原因是下边这段代码,如果在SampleController.java中添加了如下main方法,那么无论是执行main启动springboot还是通过mvn spring-boot:run方式启动springboot最终Spring只会加载SampleController.java这个类,我们写的MyDefaultExceptionHandler.java完全不会被加载.但是这种情况下如果把SampleController.java最下放的ExceptionHandler那段代码放开却可以捕捉到异常.

public static void main(String[] args) throws Exception {
    SpringApplication.run(SampleController.class, args);
}

修复方案 :

创建一个Application.java,并去掉SampleController中的main方法.

package cn.milo.controllor;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Created by admin on 2017/6/28.
 */

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

注意:SpringApplication.run(Application.class, args); 红色部分.这样写spring才会加载MyDefaultExceptionHandler.java, 原理后续我搞清楚Spring Boot再介绍吧,哈哈
正确的测试结果:

补充 :　如果MyDefaultExceptionHandler.java和SampleController.java在同一包下,则Application上方注解写为@SpringBootApplication就可以了.如果不同包的话要写成@SpringBootApplication(scanBasePackages = {“cn.milo.controllor”,”cn.milo.exception”}),因为Application.java如果注解为@SpringBootApplication,main方法默认只加载本包内的controller到spring.