org.springframework.boot.autoconfigure.web.reactive.error.AbstractErrorWebExceptionHandler Maven / Gradle / Ivy
/*
* Copyright 2012-2018 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.boot.autoconfigure.web.reactive.error;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import java.util.Map;
import reactor.core.publisher.Mono;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProviders;
import org.springframework.boot.autoconfigure.web.ResourceProperties;
import org.springframework.boot.web.reactive.error.ErrorAttributes;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.context.ApplicationContext;
import org.springframework.core.io.Resource;
import org.springframework.http.codec.HttpMessageReader;
import org.springframework.http.codec.HttpMessageWriter;
import org.springframework.util.Assert;
import org.springframework.util.CollectionUtils;
import org.springframework.web.reactive.function.BodyInserters;
import org.springframework.web.reactive.function.server.RouterFunction;
import org.springframework.web.reactive.function.server.ServerRequest;
import org.springframework.web.reactive.function.server.ServerResponse;
import org.springframework.web.reactive.result.view.ViewResolver;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.util.HtmlUtils;
/**
* Abstract base class for {@link ErrorWebExceptionHandler} implementations.
*
* @author Brian Clozel
* @since 2.0.0
* @see ErrorAttributes
*/
public abstract class AbstractErrorWebExceptionHandler
implements ErrorWebExceptionHandler, InitializingBean {
private final ApplicationContext applicationContext;
private final ErrorAttributes errorAttributes;
private final ResourceProperties resourceProperties;
private final TemplateAvailabilityProviders templateAvailabilityProviders;
private List> messageReaders = Collections.emptyList();
private List> messageWriters = Collections.emptyList();
private List viewResolvers = Collections.emptyList();
public AbstractErrorWebExceptionHandler(ErrorAttributes errorAttributes,
ResourceProperties resourceProperties,
ApplicationContext applicationContext) {
Assert.notNull(errorAttributes, "ErrorAttributes must not be null");
Assert.notNull(resourceProperties, "ResourceProperties must not be null");
Assert.notNull(applicationContext, "ApplicationContext must not be null");
this.errorAttributes = errorAttributes;
this.resourceProperties = resourceProperties;
this.applicationContext = applicationContext;
this.templateAvailabilityProviders = new TemplateAvailabilityProviders(
applicationContext);
}
/**
* Configure HTTP message writers to serialize the response body with.
* @param messageWriters the {@link HttpMessageWriter}s to use
*/
public void setMessageWriters(List> messageWriters) {
Assert.notNull(messageWriters, "'messageWriters' must not be null");
this.messageWriters = messageWriters;
}
/**
* Configure HTTP message readers to deserialize the request body with.
* @param messageReaders the {@link HttpMessageReader}s to use
*/
public void setMessageReaders(List> messageReaders) {
Assert.notNull(messageReaders, "'messageReaders' must not be null");
this.messageReaders = messageReaders;
}
/**
* Configure the {@link ViewResolver} to use for rendering views.
* @param viewResolvers the list of {@link ViewResolver}s to use
*/
public void setViewResolvers(List viewResolvers) {
this.viewResolvers = viewResolvers;
}
/**
* Extract the error attributes from the current request, to be used to populate error
* views or JSON payloads.
* @param request the source request
* @param includeStackTrace whether to include the error stacktrace information
* @return the error attributes as a Map.
*/
protected Map getErrorAttributes(ServerRequest request,
boolean includeStackTrace) {
return this.errorAttributes.getErrorAttributes(request, includeStackTrace);
}
/**
* Extract the original error from the current request.
* @param request the source request
* @return the error
*/
protected Throwable getError(ServerRequest request) {
return this.errorAttributes.getError(request);
}
/**
* Check whether the trace attribute has been set on the given request.
* @param request the source request
* @return {@code true} if the error trace has been requested, {@code false} otherwise
*/
protected boolean isTraceEnabled(ServerRequest request) {
String parameter = request.queryParam("trace").orElse("false");
return !"false".equalsIgnoreCase(parameter);
}
/**
* Render the given error data as a view, using a template view if available or a
* static HTML file if available otherwise. This will return an empty
* {@code Publisher} if none of the above are available.
* @param viewName the view name
* @param responseBody the error response being built
* @param error the error data as a map
* @return a Publisher of the {@link ServerResponse}
*/
protected Mono renderErrorView(String viewName,
ServerResponse.BodyBuilder responseBody, Map error) {
if (isTemplateAvailable(viewName)) {
return responseBody.render(viewName, error);
}
Resource resource = resolveResource(viewName);
if (resource != null) {
return responseBody.body(BodyInserters.fromResource(resource));
}
return Mono.empty();
}
private boolean isTemplateAvailable(String viewName) {
return this.templateAvailabilityProviders.getProvider(viewName,
this.applicationContext) != null;
}
private Resource resolveResource(String viewName) {
for (String location : this.resourceProperties.getStaticLocations()) {
try {
Resource resource = this.applicationContext.getResource(location);
resource = resource.createRelative(viewName + ".html");
if (resource.exists()) {
return resource;
}
}
catch (Exception ex) {
// Ignore
}
}
return null;
}
/**
* Render a default HTML "Whitelabel Error Page".
*
* Useful when no other error view is available in the application.
* @param responseBody the error response being built
* @param error the error data as a map
* @return a Publisher of the {@link ServerResponse}
*/
protected Mono renderDefaultErrorView(
ServerResponse.BodyBuilder responseBody, Map error) {
StringBuilder builder = new StringBuilder();
Object message = error.get("message");
Date timestamp = (Date) error.get("timestamp");
builder.append("Whitelabel Error Page
").append(
"This application has no configured error view, so you are seeing this as a fallback.
")
.append("").append(timestamp).append("")
.append("There was an unexpected error (type=")
.append(htmlEscape(error.get("error"))).append(", status=")
.append(htmlEscape(error.get("status"))).append(").");
if (message != null) {
builder.append("").append(htmlEscape(message)).append("");
}
builder.append("");
return responseBody.syncBody(builder.toString());
}
private String htmlEscape(Object input) {
return (input != null) ? HtmlUtils.htmlEscape(input.toString()) : null;
}
@Override
public void afterPropertiesSet() throws Exception {
if (CollectionUtils.isEmpty(this.messageWriters)) {
throw new IllegalArgumentException("Property 'messageWriters' is required");
}
}
/**
* Create a {@link RouterFunction} that can route and handle errors as JSON responses
* or HTML views.
*
* If the returned {@link RouterFunction} doesn't route to a {@code HandlerFunction},
* the original exception is propagated in the pipeline and can be processed by other
* {@link org.springframework.web.server.WebExceptionHandler}s.
* @param errorAttributes the {@code ErrorAttributes} instance to use to extract error
* information
* @return a {@link RouterFunction} that routes and handles errors
*/
protected abstract RouterFunction getRoutingFunction(
ErrorAttributes errorAttributes);
@Override
public Mono handle(ServerWebExchange exchange, Throwable throwable) {
if (exchange.getResponse().isCommitted()) {
return Mono.error(throwable);
}
this.errorAttributes.storeErrorInformation(throwable, exchange);
ServerRequest request = ServerRequest.create(exchange, this.messageReaders);
return getRoutingFunction(this.errorAttributes).route(request)
.switchIfEmpty(Mono.error(throwable))
.flatMap((handler) -> handler.handle(request))
.flatMap((response) -> write(exchange, response));
}
private Mono write(ServerWebExchange exchange,
ServerResponse response) {
// force content-type since writeTo won't overwrite response header values
exchange.getResponse().getHeaders()
.setContentType(response.headers().getContentType());
return response.writeTo(exchange, new ResponseContext());
}
private class ResponseContext implements ServerResponse.Context {
@Override
public List> messageWriters() {
return AbstractErrorWebExceptionHandler.this.messageWriters;
}
@Override
public List viewResolvers() {
return AbstractErrorWebExceptionHandler.this.viewResolvers;
}
}
}