Spring Mvc全局异常捕获

我们在开发过程中，可能希望能够统一地捕获和处理异常，免得异常处理分布在代码各处

我们可以使用spring mvc提供的全局异常捕获来实现这样的功能

首先我们新建一个专门复杂异常处理的工程

com.lzw.exception.exception包里是我们自定义的Exception

package com.lzw.exceptions.exception;public class BookingExpiredException extends Exception {/** *  */private static final long serialVersionUID = 573537091646842099L;}

com.lzw.exceptions.handler包里面是我们对异常的处理

package com.lzw.exceptions.handler;import org.springframework.http.HttpStatus;import org.springframework.web.bind.annotation.ExceptionHandler;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.bind.annotation.ResponseStatus;import com.lzw.exceptions.exception.BookingExpiredException;import com.lzw.exceptions.exception.BookingNoSeatsException;public class BookingExceptionHandler {@ExceptionHandler(value = BookingNoSeatsException.class)@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR, reason = "no seats")@ResponseBodypublic void handleNoSeatsException(BookingNoSeatsException exception) {System.out.println("BookingNoSeatsException!");}@ExceptionHandler(value = BookingExpiredException.class)@ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR, reason = "booking expired")@ResponseBodypublic void handleExpiredException(BookingExpiredException exception) {System.out.println("BookingExpiredException!");}}

com.lzw.exceptions.resolver包里面的类负责对异常进行捕获

package com.lzw.exceptions.resolver;import java.lang.reflect.Method;import org.springframework.core.Ordered;import org.springframework.web.method.HandlerMethod;import org.springframework.web.method.annotation.ExceptionHandlerMethodResolver;import org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver;import org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod;public class BookingExceptionHandlerResolver extendsExceptionHandlerExceptionResolver {private Object handler;private ExceptionHandlerMethodResolver methodResolver;public BookingExceptionHandlerResolver() {setOrder(Ordered.HIGHEST_PRECEDENCE);}public void setExceptionHandler(final Object handler) {this.handler = handler;this.methodResolver = new ExceptionHandlerMethodResolver(handler.getClass());}protected ServletInvocableHandlerMethod getExceptionHandlerMethod(final HandlerMethod handlerMethod, final Exception exception) {ServletInvocableHandlerMethod result = super.getExceptionHandlerMethod(handlerMethod, exception);if (result != null) {return result;}Method method = this.methodResolver.resolveMethod(exception);return (method != null) ? new ServletInvocableHandlerMethod(this.handler, method) : null;};}

ExceptionHandlerExceptionResolver是spring mvc默认的异常处理器，我们可以通过继承它来实现自己的处理逻辑

例如上面，我们继承并实现了自己的BookingExceptionHandlerResolver，注入自己的异常处理器（BookingExceptionHandler），重写了getExceptionHandlerMethod,使得异常发生时能从BookingExceptionHandler里面取得处理该异常的处理方法

当业务代码抛出异常的时候，如果所在的Controller没有对异常进行处理，那么异常就会抛出到Spring Mvc，Spring Mvc会在各个ExceptionHandlerExceptionResolver类（或子类）里面查找能够处理该异常的handler，然后在handler里面找到处理那种异常的方法并执行

编写好以上类后，我们通过把ExceptionHandlerExceptionResolver给声明为bean

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans            http://www.springframework.org/schema/beans/spring-beans-3.2.xsd            http://www.springframework.org/schema/context            http://www.springframework.org/schema/context/spring-context-3.2.xsd            http://www.springframework.org/schema/aop            http://www.springframework.org/schema/aop/spring-aop-3.2.xsd            http://www.springframework.org/schema/tx            http://www.springframework.org/schema/tx/spring-tx-3.2.xsd            http://www.springframework.org/schema/mvc            http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd            http://www.springframework.org/schema/context            http://www.springframework.org/schema/context/spring-context-3.2.xsd"><bean class="com.lzw.exceptions.resolver.BookingExceptionHandlerResolver"><property name="exceptionHandler"><bean class="com.lzw.exceptions.handler.BookingExceptionHandler" /></property><property name="messageConverters"><list><beanclass="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" /></list></property></bean><bean class="com.lzw.exceptions.resolver.PayExceptionHandlerResolver"><property name="exceptionHandler"><bean class="com.lzw.exceptions.handler.PayExceptionHandler" /></property><property name="messageConverters"><list><beanclass="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" /></list></property></bean></beans>

这样最后把整个工程打成jar包，给其他工程使用

下面新建一个代表业务的工程

把之前的Exception工程通过maven给依赖进来

然后在Spring Mvc配置文件中引入Exception工程的配置文件

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context"xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"xsi:schemaLocation="http://www.springframework.org/schema/beans            http://www.springframework.org/schema/beans/spring-beans-3.2.xsd            http://www.springframework.org/schema/context            http://www.springframework.org/schema/context/spring-context-3.2.xsd            http://www.springframework.org/schema/aop            http://www.springframework.org/schema/aop/spring-aop-3.2.xsd            http://www.springframework.org/schema/tx            http://www.springframework.org/schema/tx/spring-tx-3.2.xsd            http://www.springframework.org/schema/mvc            http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd            http://www.springframework.org/schema/context            http://www.springframework.org/schema/context/spring-context-3.2.xsd"><context:component-scan base-package="com.lzw.business" /><mvc:annotation-driven /><import resource="classpath:com/lzw/exceptions/exceptions.xml"/></beans>

最后看看Mvc的Controller

package com.lzw.business;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;import com.lzw.exceptions.exception.BookingExpiredException;import com.lzw.exceptions.exception.BookingNoSeatsException;import com.lzw.exceptions.exception.PayNoMoneyException;import com.lzw.exceptions.exception.PayTimeoutException;@Controllerpublic class Test {@RequestMapping(value = "/testbooknoseats")public void TestBookingNoSeats() throws BookingNoSeatsException {throw new BookingNoSeatsException();}@RequestMapping(value = "/testbookexpired")public void TestBookingExpired() throws BookingExpiredException {throw new BookingExpiredException();}@RequestMapping(value = "/paynomoney")public void TestPayNoMoney() throws PayNoMoneyException {throw new PayNoMoneyException();}@RequestMapping(value = "/paytimeout")public void TestPayTimeout() throws PayTimeoutException {throw new PayTimeoutException();}}

测试一下