springboot ErrorPageFilter的实际应用详解

private void doFilter(HttpServletRequest request, HttpServletResponse response,
            FilterChain chain) throws IOException, ServletException {
    ErrorWrapperResponse wrapped = new ErrorWrapperResponse(response);
    try {
        chain.doFilter(request, wrapped);
        if (wrapped.hasErrorToSend()) {
            // 重点关注此方法
            handleErrorStatus(request, response, wrapped.getStatus(),
                    wrapped.getMessage());
            response.flushBuffer();
        }
        else if (!request.isAsyncStarted() && !response.isCommitted()) {
            response.flushBuffer();
        }
    }
    catch (Throwable ex) {
        Throwable exceptionToHandle = ex;
        if (ex instanceof NestedServletException) {
            exceptionToHandle = ((NestedServletException) ex).getRootCause();
        }
        handleException(request, response, wrapped, exceptionToHandle);
        response.flushBuffer();
    }
}

private void handleErrorStatus(HttpServletRequest request,
            HttpServletResponse response, int status, String message)
                    throws ServletException, IOException {
    if (response.isCommitted()) {
        handleCommittedResponse(request, null);
        return;
    }
    // 获取错误页，来关注下这个属性this.statuses，就是一个map，而错误页就是从这属性中获取，那此属性的内容是什么时候添加进去的呢
    String errorPath = getErrorPath(this.statuses, status);
    if (errorPath == null) {
        response.sendError(status, message);
        return;
    }
    response.setStatus(status);
    setErrorAttributes(request, status, message);
    // 拿到错误页地址后，通过服务器重定向的方式跳转到错误页面
    request.getRequestDispatcher(errorPath).forward(request, response);
}

@Override
public void addErrorPages(ErrorPage... errorPages) {
    for (ErrorPage errorPage : errorPages) {
        if (errorPage.isGlobal()) {
            this.global = errorPage.getPath();
        }
        else if (errorPage.getStatus() != null) {
            this.statuses.put(errorPage.getStatus().value(), errorPage.getPath());
        }
        else {
            this.exceptions.put(errorPage.getException(), errorPage.getPath());
        }
    }
}

public interface ErrorPageRegistrar {
    /**
     * Register pages as required with the given registry.
     * @param registry the error page registry
     */
    void registerErrorPages(ErrorPageRegistry registry);
}

@Component
public class MyErrorPage implements ErrorPageRegistrar {
    @Override
    public void registerErrorPages(ErrorPageRegistry registry) {
        ErrorPage error404Page = new ErrorPage(HttpStatus.NOT_FOUND, "/WEB-INF/errorpage/404.html");
        ErrorPage error405Page = new ErrorPage(HttpStatus.METHOD_NOT_ALLOWED, "/WEB-INF/errorpage/405.html");
        ErrorPage error500Page = new ErrorPage(HttpStatus.INTERNAL_SERVER_ERROR, "/WEB-INF/errorpage/500.html");
        registry.addErrorPages(error404Page, error405Page, error500Page);
    }
}

    @Bean
    public ErrorPageFilter errorPageFilter() {
        return new ErrorPageFilter();
    }
 
    @Bean
    public FilterRegistrationBean disableSpringBootErrorFilter(ErrorPageFilter filter) {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(filter);
        filterRegistrationBean.setEnabled(false);
        return filterRegistrationBean;
    }

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//
package org.springframework.boot.web.servlet.support;
import javax.servlet.DispatcherType;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration(
    proxyBeanMethods = false
)
class ErrorPageFilterConfiguration {
    ErrorPageFilterConfiguration() {
    }
    @Bean
    ErrorPageFilter errorPageFilter() {
        return new ErrorPageFilter();
    }
    @Bean
    FilterRegistrationBean<ErrorPageFilter> errorPageFilterRegistration(ErrorPageFilter filter) {
        FilterRegistrationBean<ErrorPageFilter> registration = new FilterRegistrationBean(filter, new ServletRegistrationBean[0]);
        registration.setOrder(filter.getOrder());
        registration.setDispatcherTypes(DispatcherType.REQUEST, new DispatcherType[]{DispatcherType.ASYNC});
        return registration;
    }
}

@SpringBootApplication
public class App extends SpringBootServletInitializer {
public App() {
    super();
    //下面设置为false
    setRegisterErrorPageFilter(false); 
}
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
    return application.sources(App.class);
}
public static void main(String[] args) {
    SpringApplication.run(App.class, args);
}