Spring MVC入门（十）：异常处理

异常处理

• 简介

SpringMVC提供了一个处理控制器方法执行过程中所出现的异常的接口：HandlerExceptionResolver
HandlerExceptionResolver接口的实现类有：DefaultHandlerExceptionResolver和
SimpleMappingExceptionResolver
SpringMVC提供了自定义的异常处理器SimpleMappingExceptionResolver

• 双击shift，搜索DefaultHandlerExceptionResolver



• ctrl + h 选中AbstractHandlerExceptionResolver



• 查看DefaultHandlerExceptionResolver源码，当出现异常时，返回1个新的ModelAndView替换我们自己的ModelAndView

        @Override
  @Nullable
  protected ModelAndView doResolveException(
      HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {

    try {
      if (ex instanceof HttpRequestMethodNotSupportedException) {
        return handleHttpRequestMethodNotSupported(
            (HttpRequestMethodNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMediaTypeNotSupportedException) {
        return handleHttpMediaTypeNotSupported(
            (HttpMediaTypeNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMediaTypeNotAcceptableException) {
        return handleHttpMediaTypeNotAcceptable(
            (HttpMediaTypeNotAcceptableException) ex, request, response, handler);
      }
      else if (ex instanceof MissingPathVariableException) {
        return handleMissingPathVariable(
            (MissingPathVariableException) ex, request, response, handler);
      }
      else if (ex instanceof MissingServletRequestParameterException) {
        return handleMissingServletRequestParameter(
            (MissingServletRequestParameterException) ex, request, response, handler);
      }
      else if (ex instanceof ServletRequestBindingException) {
        return handleServletRequestBindingException(
            (ServletRequestBindingException) ex, request, response, handler);
      }
      else if (ex instanceof ConversionNotSupportedException) {
        return handleConversionNotSupported(
            (ConversionNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof TypeMismatchException) {
        return handleTypeMismatch(
            (TypeMismatchException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMessageNotReadableException) {
        return handleHttpMessageNotReadable(
            (HttpMessageNotReadableException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMessageNotWritableException) {
        return handleHttpMessageNotWritable(
            (HttpMessageNotWritableException) ex, request, response, handler);
      }
      else if (ex instanceof MethodArgumentNotValidException) {
        return handleMethodArgumentNotValidException(
            (MethodArgumentNotValidException) ex, request, response, handler);
      }
      else if (ex instanceof MissingServletRequestPartException) {
        return handleMissingServletRequestPartException(
            (MissingServletRequestPartException) ex, request, response, handler);
      }
      else if (ex instanceof BindException) {
        return handleBindException((BindException) ex, request, response, handler);
      }
      else if (ex instanceof NoHandlerFoundException) {
        return handleNoHandlerFoundException(
            (NoHandlerFoundException) ex, request, response, handler);
      }
      else if (ex instanceof AsyncRequestTimeoutException) {
        return handleAsyncRequestTimeoutException(
            (AsyncRequestTimeoutException) ex, request, response, handler);
      }
    }
    catch (Exception handlerEx) {
      if (logger.isWarnEnabled()) {
        logger.warn("Failure while trying to resolve exception [" + ex.getClass().getName() + "]", handlerEx);
      }
    }
    return null;
  }

• 实现代码

# springmvc配置文件中配置异常处理
    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <prop key="java.lang.ArithmeticException">error</prop>
            </props>
        </property>
        <!-- 设置将异常信息共享在请求域中的键 -->
        <property name="exceptionAttribute" value="ex"></property>
    </bean>

# 编写错误页面
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
出现错误
<p th:text="${ex}"></p>
</body>
</html>

# 模拟1个异常
    @RequestMapping("/testExceptionHandler")
    public String testExceptionHandler(){
        System.out.println(1/0);
        return "success";
    }

• 注解配置异常处理

# 注释掉springmvc配置文件中配置异常处理
    <bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <prop key="java.lang.ArithmeticException">error</prop>
            </props>
        </property>
        <!-- 设置将异常信息共享在请求域中的键 -->
        <property name="exceptionAttribute" value="ex"></property>
    </bean>

# 编写错误页面
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
出现错误
<p th:text="${ex}"></p>
</body>
</html>

# 模拟1个异常
    @RequestMapping("/testExceptionHandler")
    public String testExceptionHandler(){
        System.out.println(1/0);
        return "success";
    }

# 异常处理配置
@ControllerAdvice
public class ExceptionController {
    // 出现如下异常时跳转到错误页面
    @ExceptionHandler(value = {ArithmeticException.class, NullPointerException.class})
    public String testException(Exception ex, Model model){    // 将错误信息通过model设置到域对象中，前端可以获取
        model.addAttribute("ex", ex);
        return "error";
    }

}