/*
* Copyright 2012-2014 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;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.Servlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.AutoConfigureBefore;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionOutcome;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.autoconfigure.condition.SearchStrategy;
import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
import org.springframework.boot.autoconfigure.template.TemplateAvailabilityProvider;
import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer;
import org.springframework.boot.context.embedded.ErrorPage;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ConditionContext;
import org.springframework.context.annotation.Conditional;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.expression.MapAccessor;
import org.springframework.core.Ordered;
import org.springframework.core.io.support.SpringFactoriesLoader;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.expression.Expression;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;
import org.springframework.util.PropertyPlaceholderHelper;
import org.springframework.util.PropertyPlaceholderHelper.PlaceholderResolver;
import org.springframework.web.servlet.DispatcherServlet;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.view.BeanNameViewResolver;
import org.springframework.web.util.HtmlUtils;
/**
* {@link EnableAutoConfiguration Auto-configuration} to render errors via a MVC error
* controller.
*
* @author Dave Syer
* @author Andy Wilkinson
*/
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class })
@ConditionalOnWebApplication
// Ensure this loads before the main WebMvcAutoConfiguration so that the error View is
// available
@AutoConfigureBefore(WebMvcAutoConfiguration.class)
@Configuration
public class ErrorMvcAutoConfiguration implements EmbeddedServletContainerCustomizer {
@Value("${error.path:/error}")
private String errorPath = "/error";
@Autowired
private ServerProperties properties;
@Bean
@ConditionalOnMissingBean(value = ErrorAttributes.class, search = SearchStrategy.CURRENT)
public DefaultErrorAttributes errorAttributes() {
return new DefaultErrorAttributes();
}
@Bean
@ConditionalOnMissingBean(value = ErrorController.class, search = SearchStrategy.CURRENT)
public BasicErrorController basicErrorController(ErrorAttributes errorAttributes) {
return new BasicErrorController(errorAttributes);
}
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.addErrorPages(new ErrorPage(this.properties.getServletPrefix()
+ this.errorPath));
}
@Configuration
@ConditionalOnProperty(prefix = "error.whitelabel", name = "enabled", matchIfMissing = true)
@Conditional(ErrorTemplateMissingCondition.class)
protected static class WhitelabelErrorViewConfiguration {
private final SpelView defaultErrorView = new SpelView(
"<html><body><h1>Whitelabel Error Page</h1>"
+ "<p>This application has no explicit mapping for /error, so you are seeing this as a fallback.</p>"
+ "<div id='created'>${timestamp}</div>"
+ "<div>There was an unexpected error (type=${error}, status=${status}).</div>"
+ "<div>${message}</div></body></html>");
@Bean(name = "error")
@ConditionalOnMissingBean(name = "error")
public View defaultErrorView() {
return this.defaultErrorView;
}
// If the user adds @EnableWebMvc then the bean name view resolver from
// WebMvcAutoConfiguration disappears, so add it back in to avoid disappointment.
@Bean
@ConditionalOnMissingBean(BeanNameViewResolver.class)
public BeanNameViewResolver beanNameViewResolver() {
BeanNameViewResolver resolver = new BeanNameViewResolver();
resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 10);
return resolver;
}
}
private static class ErrorTemplateMissingCondition extends SpringBootCondition {
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context,
AnnotatedTypeMetadata metadata) {
List<TemplateAvailabilityProvider> availabilityProviders = SpringFactoriesLoader
.loadFactories(TemplateAvailabilityProvider.class,
context.getClassLoader());
for (TemplateAvailabilityProvider availabilityProvider : availabilityProviders) {
if (availabilityProvider.isTemplateAvailable("error",
context.getEnvironment(), context.getClassLoader(),
context.getResourceLoader())) {
return ConditionOutcome.noMatch("Template from "
+ availabilityProvider + " found for error view");
}
}
return ConditionOutcome.match("No error template view detected");
};
}
/**
* Simple {@link View} implementation that resolves variables as SpEL expressions.
*/
private static class SpelView implements View {
private final String template;
private final StandardEvaluationContext context = new StandardEvaluationContext();
private PropertyPlaceholderHelper helper;
private PlaceholderResolver resolver;
public SpelView(String template) {
this.template = template;
this.context.addPropertyAccessor(new MapAccessor());
this.helper = new PropertyPlaceholderHelper("${", "}");
this.resolver = new SpelPlaceholderResolver(this.context);
}
@Override
public String getContentType() {
return "text/html";
}
@Override
public void render(Map<String, ?> model, HttpServletRequest request,
HttpServletResponse response) throws Exception {
if (response.getContentType() == null) {
response.setContentType(getContentType());
}
Map<String, Object> map = new HashMap<String, Object>(model);
map.put("path", request.getContextPath());
this.context.setRootObject(map);
String result = this.helper.replacePlaceholders(this.template, this.resolver);
response.getWriter().append(result);
}
}
/**
* SpEL based {@link PlaceholderResolver}.
*/
private static class SpelPlaceholderResolver implements PlaceholderResolver {
private final SpelExpressionParser parser = new SpelExpressionParser();
private final StandardEvaluationContext context;
public SpelPlaceholderResolver(StandardEvaluationContext context) {
this.context = context;
}
@Override
public String resolvePlaceholder(String name) {
Expression expression = this.parser.parseExpression(name);
try {
Object value = expression.getValue(this.context);
return HtmlUtils.htmlEscape(value == null ? null : value.toString());
}
catch (Exception ex) {
return null;
}
}
}
}