[JAVA] Error handling when the maximum file size is exceeded when uploading a file with Spring Boot

You can set the maximum file size when uploading a file with Spring Boot. Set the following parameters in application.propertes

spring.servlet.multipart.enabled=true
#Maximum size of one file
spring.servlet.multipart.max-file-size=10MB
#Maximum size of all multiple files
spring.servlet.multipart.max-request-size=50MB

An error will be displayed if you try to upload a file larger than the size set here, but an example when you want to customize this error handling is described below.

1. Create child class of HandlerExceptionResolver Create the following class anywhere in the project. This makes it possible to get an exception for file size error.

@Component
public class ExceptionResolver implements HandlerExceptionResolver {
  @Override
  public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception e) {
    ModelAndView modelAndView = new ModelAndView();
    if (e instanceof MultipartException && e.getCause() instanceof IllegalStateException && e.getCause().getCause() instanceof FileSizeLimitExceededException) {
      //Messages you want to display, etc.
      modelAndView.addObject("message", "File size exceeded");
    }
    //Specify the screen you want to transition to
    modelAndView.setViewName("error");
    return modelAndView;
  }
}

2. Setting Max Swallow Size of built-in tomcat Set MaxSwallowSize of built-in Tomcat to -1 because 1. alone does not work well. The following methods are described in XXXXApplication.java where the main method is located.

 @Bean
  public TomcatServletWebServerFactory containerFactory() {
    return new TomcatServletWebServerFactory() {
      protected void customizeConnector(Connector connector) {
        super.customizeConnector(connector);
        if (connector.getProtocolHandler() instanceof AbstractHttp11Protocol) {

          ((AbstractHttp11Protocol<?>) connector.getProtocolHandler()).setMaxSwallowSize(-1);
        }
      }
    };
  }