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Add support for global @ExceptionHandler methods

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Before this change @ExceptionHandler methods could be located in and
apply locally within a controller. The change makes it possible to have
such methods applicable globally regardless of the controller that
raised the exception.

The easiest way to do that is to add them to a class annotated with
`@ExceptionResolver`, a new annotation that is also an `@Component`
annotation (and therefore works with component scanning). It is also
possible to register classes containing `@ExceptionHandler` methods
directly with the ExceptionHandlerExceptionResolver.

When multiple `@ExceptionResolver` classes are detected, or registered
directly, the order in which they're used depends on the the `@Order`
annotation (if present) or on the value of the order field (if the
Ordered interface is implemented).

Issue: SPR-9112
This commit is contained in:
Rossen Stoyanchev
2012-06-11 14:34:44 -04:00
parent ccd2da37ce
commit c846198e46
6 changed files with 334 additions and 74 deletions
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101
spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/ExceptionHandlerExceptionResolver.java
View File

@@ -18,15 +18,23 @@ package org.springframework.web.servlet.mvc.method.annotation;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.Source;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.http.converter.ByteArrayHttpMessageConverter;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
@@ -34,6 +42,7 @@ import org.springframework.http.converter.xml.SourceHttpMessageConverter;
import org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter;
import org.springframework.web.accept.ContentNegotiationManager;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ExceptionResolver;
import org.springframework.web.context.request.ServletWebRequest;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.method.annotation.ExceptionHandlerMethodResolver;
@@ -49,6 +58,8 @@ import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionResolver;
import edu.emory.mathcs.backport.java.util.Collections;
/**
* An {@link AbstractHandlerMethodExceptionResolver} that resolves exceptions
* through {@code @ExceptionHandler} methods.
@@ -62,7 +73,7 @@ import org.springframework.web.servlet.handler.AbstractHandlerMethodExceptionRes
* @since 3.1
*/
public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExceptionResolver implements
InitializingBean {
InitializingBean, ApplicationContextAware {
private List<HandlerMethodArgumentResolver> customArgumentResolvers;
@@ -72,13 +83,18 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
private ContentNegotiationManager contentNegotiationManager = new ContentNegotiationManager();
private final Map<Class<?>, ExceptionHandlerMethodResolver> exceptionHandlerMethodResolvers =
new ConcurrentHashMap<Class<?>, ExceptionHandlerMethodResolver>();
private final Map<Class<?>, ExceptionHandlerMethodResolver> exceptionHandlersByType =
new ConcurrentHashMap<Class<?>, ExceptionHandlerMethodResolver>();
private final Map<Object, ExceptionHandlerMethodResolver> globalExceptionHandlers =
new LinkedHashMap<Object, ExceptionHandlerMethodResolver>();
private HandlerMethodArgumentResolverComposite argumentResolvers;
private HandlerMethodReturnValueHandlerComposite returnValueHandlers;
private ApplicationContext applicationContext;
/**
* Default constructor.
*/
@@ -193,6 +209,22 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
this.contentNegotiationManager = contentNegotiationManager;
}
/**
* Provide instances of objects with {@link ExceptionHandler @ExceptionHandler}
* methods to apply globally, i.e. regardless of the selected controller.
* <p>{@code @ExceptionHandler} methods in the controller are always looked
* up before {@code @ExceptionHandler} methods in global handlers.
*/
public void setGlobalExceptionHandlers(Object... handlers) {
for (Object handler : handlers) {
this.globalExceptionHandlers.put(handler, new ExceptionHandlerMethodResolver(handler.getClass()));
}
}
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
public void afterPropertiesSet() {
if (this.argumentResolvers == null) {
List<HandlerMethodArgumentResolver> resolvers = getDefaultArgumentResolvers();
@@ -202,6 +234,7 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
List<HandlerMethodReturnValueHandler> handlers = getDefaultReturnValueHandlers();
this.returnValueHandlers = new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
}
initGlobalExceptionHandlers();
}
/**
@@ -255,6 +288,36 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
return handlers;
}
private void initGlobalExceptionHandlers() {
if (this.applicationContext == null) {
logger.warn("Can't detect @ExceptionResolver components if the ApplicationContext property is not set");
}
else {
String[] beanNames = this.applicationContext.getBeanNamesForType(Object.class);
for (String name : beanNames) {
Class<?> type = this.applicationContext.getType(name);
if (AnnotationUtils.findAnnotation(type , ExceptionResolver.class) != null) {
Object bean = this.applicationContext.getBean(name);
this.globalExceptionHandlers.put(bean, new ExceptionHandlerMethodResolver(bean.getClass()));
}
}
}
if (this.globalExceptionHandlers.size() > 0) {
sortGlobalExceptionHandlers();
}
}
private void sortGlobalExceptionHandlers() {
Map<Object, ExceptionHandlerMethodResolver> handlersCopy =
new HashMap<Object, ExceptionHandlerMethodResolver>(this.globalExceptionHandlers);
List<Object> handlers = new ArrayList<Object>(handlersCopy.keySet());
Collections.sort(handlers, new AnnotationAwareOrderComparator());
this.globalExceptionHandlers.clear();
for (Object handler : handlers) {
this.globalExceptionHandlers.put(handler, handlersCopy.get(handler));
}
}
/**
* Find an @{@link ExceptionHandler} method and invoke it to handle the
* raised exception.
@@ -307,24 +370,32 @@ public class ExceptionHandlerExceptionResolver extends AbstractHandlerMethodExce
* @return a method to handle the exception, or {@code null}
*/
protected ServletInvocableHandlerMethod getExceptionHandlerMethod(HandlerMethod handlerMethod, Exception exception) {
if (handlerMethod == null) {
return null;
if (handlerMethod != null) {
Class<?> handlerType = handlerMethod.getBeanType();
ExceptionHandlerMethodResolver resolver = this.exceptionHandlersByType.get(handlerType);
if (resolver == null) {
resolver = new ExceptionHandlerMethodResolver(handlerType);
this.exceptionHandlersByType.put(handlerType, resolver);
}
Method method = resolver.resolveMethod(exception);
if (method != null) {
return new ServletInvocableHandlerMethod(handlerMethod.getBean(), method);
}
}
Class<?> handlerType = handlerMethod.getBeanType();
Method method = getExceptionHandlerMethodResolver(handlerType).resolveMethod(exception);
return (method != null ? new ServletInvocableHandlerMethod(handlerMethod.getBean(), method) : null);
return getGlobalExceptionHandlerMethod(exception);
}
/**
* Return a method resolver for the given handler type, never {@code null}.
* Return a global {@code @ExceptionHandler} method for the given exception or {@code null}.
*/
private ExceptionHandlerMethodResolver getExceptionHandlerMethodResolver(Class<?> handlerType) {
ExceptionHandlerMethodResolver resolver = this.exceptionHandlerMethodResolvers.get(handlerType);
if (resolver == null) {
resolver = new ExceptionHandlerMethodResolver(handlerType);
this.exceptionHandlerMethodResolvers.put(handlerType, resolver);
private ServletInvocableHandlerMethod getGlobalExceptionHandlerMethod(Exception exception) {
for (Entry<Object, ExceptionHandlerMethodResolver> entry : this.globalExceptionHandlers.entrySet()) {
Method method = entry.getValue().resolveMethod(exception);
if (method != null) {
return new ServletInvocableHandlerMethod(entry.getKey(), method);
}
}
return resolver;
return null;
}
}