spring boot在异常的处理中，默认实现了一个EmbeddedServletContainerCustomizer并定义了一个错误页面到”/error”中，在ErrorMvcAutoConfiguration源码中可以看到
/**
* {@link EmbeddedServletContainerCustomizer} that configures the container‘s error
* pages.
*/
private static class ErrorPageCustomizer
implements EmbeddedServletContainerCustomizer, Ordered {
private final ServerProperties properties;
protected ErrorPageCustomizer(ServerProperties properties) {
this.properties = properties;
}
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.addErrorPages(new ErrorPage(this.properties.getServletPrefix()
+ this.properties.getError().getPath()));
}
@Override
public int getOrder() {
return 0;
}
}还配置了一个默认的白板页面，在源码可以看到
@Configuration
@ConditionalOnProperty(prefix = "server.error.whitelabel", name = "enabled", matchIfMissing = true)
@Conditional(ErrorTemplateMissingCondition.class)
protected static class WhitelabelErrorViewConfiguration {
private final SpelView defaultErrorView = new SpelView(
"<html><body><h1>Whitelabel Error Page</h1>"
+ "<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>"
+ "<div id=‘created‘>${timestamp}</div>"
+ "<div>There was an unexpected error (type=${error}, status=${status}).</div>"
+ "<div>${message}</div></body></html>");
@Bean(name = "error")
@ConditionalOnMissingBean(name = "error")
public View defaultErrorView() {
return this.defaultErrorView;
}
// If the user adds @EnableWebMvc then the bean name view resolver from
// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
@Bean
@ConditionalOnMissingBean(BeanNameViewResolver.class)
public BeanNameViewResolver beanNameViewResolver() {
BeanNameViewResolver resolver = new BeanNameViewResolver();
resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return resolver;
}
}在路径的处理上，定义了一个BasicErrorController来处理异常，ErrorAttributes来装载错误异常到前端
@Controller
@RequestMapping("${server.error.path:${error.path:/error}}")
public class BasicErrorController extends AbstractErrorController {
private final ErrorProperties errorProperties;
//...
@RequestMapping(produces = "text/html")
public ModelAndView errorHtml(HttpServletRequest request,
HttpServletResponse response) {
response.setStatus(getStatus(request).value());
Map<String, Object> model = getErrorAttributes(request,
isIncludeStackTrace(request, MediaType.TEXT_HTML));
return new ModelAndView("error", model);
}
@RequestMapping
@ResponseBody
public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
Map<String, Object> body = getErrorAttributes(request,
isIncludeStackTrace(request, MediaType.ALL));
HttpStatus status = getStatus(request);
return new ResponseEntity<Map<String, Object>>(body, status);
}
//...}默认只要你请求的content-type是”text/html”则返回一个白版页面给你，如果是其他的content-type，则返回一个json的数据给你。
若你想自定义异常，可以通过以下方式来处理
1.你可以默认在classpath:templates下定义一个error.ftl的freemarker模版来定义异常页面
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h1> error page !! </h1>
${timestamp?string(‘yyyy-MM-dd HH:mm:ss‘)}<br/><br/>
${status} <br/><br/>
${error} <br/><br/>
${message} <br/><br/>
${path} <br/><br/>
</body>
</html>2.可以利用@ExceptionHandler来为某个特定的controller拦截异常，并返回一个json数据，当然你也可以定义全部的controller来拦截异常
@ControllerAdvice(basePackageClasses = FooController.class)
public class FooControllerAdvice extends ResponseEntityExceptionHandler {
@ExceptionHandler(YourException.class)
@ResponseBody
ResponseEntity<?> handleControllerException(HttpServletRequest request, Throwable ex) {
HttpStatus status = getStatus(request);
return new ResponseEntity<>(new CustomErrorType(status.value(), ex.getMessage()), status);
}
private HttpStatus getStatus(HttpServletRequest request) {
Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
if (statusCode == null) {
return HttpStatus.INTERNAL_SERVER_ERROR;
}
return HttpStatus.valueOf(statusCode);
}
}3.还可以自定义server的错误页面
@Bean
public EmbeddedServletContainerCustomizer containerCustomizer(){
return new MyCustomizer();
}
// ...
private static class MyCustomizer implements EmbeddedServletContainerCustomizer {
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.addErrorPages(new ErrorPage(HttpStatus.BAD_REQUEST, "/500"));
}
}