/*
* Copyright 2002-2017 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.web.servlet;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
/**
* Handler execution chain, consisting of handler object and any handler interceptors.
* Returned by HandlerMapping's {@link HandlerMapping#getHandler} method.
*
* @author Juergen Hoeller
* @since 20.06.2003
* @see HandlerInterceptor
*/
public class HandlerExecutionChain {
private static final Log logger = LogFactory.getLog(HandlerExecutionChain.class);
private final Object handler;
private HandlerInterceptor[] interceptors;
private List<HandlerInterceptor> interceptorList;
private int interceptorIndex = -1;
/**
* Create a new HandlerExecutionChain.
* @param handler the handler object to execute
*/
public HandlerExecutionChain(Object handler) {
this(handler, (HandlerInterceptor[]) null);
}
/**
* Create a new HandlerExecutionChain.
* @param handler the handler object to execute
* @param interceptors the array of interceptors to apply
* (in the given order) before the handler itself executes
*/
public HandlerExecutionChain(Object handler, HandlerInterceptor... interceptors) {
if (handler instanceof HandlerExecutionChain) {
HandlerExecutionChain originalChain = (HandlerExecutionChain) handler;
this.handler = originalChain.getHandler();
this.interceptorList = new ArrayList<>();
CollectionUtils.mergeArrayIntoCollection(originalChain.getInterceptors(), this.interceptorList);
CollectionUtils.mergeArrayIntoCollection(interceptors, this.interceptorList);
}
else {
this.handler = handler;
this.interceptors = interceptors;
}
}
/**
* Return the handler object to execute.
* @return the handler object (may be {@code null})
*/
public Object getHandler() {
return this.handler;
}
public void addInterceptor(HandlerInterceptor interceptor) {
initInterceptorList().add(interceptor);
}
public void addInterceptors(HandlerInterceptor... interceptors) {
if (!ObjectUtils.isEmpty(interceptors)) {
CollectionUtils.mergeArrayIntoCollection(interceptors, initInterceptorList());
}
}
private List<HandlerInterceptor> initInterceptorList() {
if (this.interceptorList == null) {
this.interceptorList = new ArrayList<>();
if (this.interceptors != null) {
// An interceptor array specified through the constructor
CollectionUtils.mergeArrayIntoCollection(this.interceptors, this.interceptorList);
}
}
this.interceptors = null;
return this.interceptorList;
}
/**
* Return the array of interceptors to apply (in the given order).
* @return the array of HandlerInterceptors instances (may be {@code null})
*/
public HandlerInterceptor[] getInterceptors() {
if (this.interceptors == null && this.interceptorList != null) {
this.interceptors = this.interceptorList.toArray(new HandlerInterceptor[this.interceptorList.size()]);
}
return this.interceptors;
}
/**
* Apply preHandle methods of registered interceptors.
* @return {@code true} if the execution chain should proceed with the
* next interceptor or the handler itself. Else, DispatcherServlet assumes
* that this interceptor has already dealt with the response itself.
*/
boolean applyPreHandle(HttpServletRequest request, HttpServletResponse response) throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = 0; i < interceptors.length; i++) {
HandlerInterceptor interceptor = interceptors[i];
if (!interceptor.preHandle(request, response, this.handler)) {
triggerAfterCompletion(request, response, null);
return false;
}
this.interceptorIndex = i;
}
}
return true;
}
/**
* Apply postHandle methods of registered interceptors.
*/
void applyPostHandle(HttpServletRequest request, HttpServletResponse response, ModelAndView mv) throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = interceptors.length - 1; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
interceptor.postHandle(request, response, this.handler, mv);
}
}
}
/**
* Trigger afterCompletion callbacks on the mapped HandlerInterceptors.
* Will just invoke afterCompletion for all interceptors whose preHandle invocation
* has successfully completed and returned true.
*/
void triggerAfterCompletion(HttpServletRequest request, HttpServletResponse response, Exception ex)
throws Exception {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = this.interceptorIndex; i >= 0; i--) {
HandlerInterceptor interceptor = interceptors[i];
try {
interceptor.afterCompletion(request, response, this.handler, ex);
}
catch (Throwable ex2) {
logger.error("HandlerInterceptor.afterCompletion threw exception", ex2);
}
}
}
}
/**
* Apply afterConcurrentHandlerStarted callback on mapped AsyncHandlerInterceptors.
*/
void applyAfterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response) {
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
for (int i = interceptors.length - 1; i >= 0; i--) {
if (interceptors[i] instanceof AsyncHandlerInterceptor) {
try {
AsyncHandlerInterceptor asyncInterceptor = (AsyncHandlerInterceptor) interceptors[i];
asyncInterceptor.afterConcurrentHandlingStarted(request, response, this.handler);
}
catch (Throwable ex) {
logger.error("Interceptor [" + interceptors[i] + "] failed in afterConcurrentHandlingStarted", ex);
}
}
}
}
}
/**
* Delegates to the handler's {@code toString()}.
*/
@Override
public String toString() {
Object handler = getHandler();
if (handler == null) {
return "HandlerExecutionChain with no handler";
}
StringBuilder sb = new StringBuilder();
sb.append("HandlerExecutionChain with handler [").append(handler).append("]");
HandlerInterceptor[] interceptors = getInterceptors();
if (!ObjectUtils.isEmpty(interceptors)) {
sb.append(" and ").append(interceptors.length).append(" interceptor");
if (interceptors.length > 1) {
sb.append("s");
}
}
return sb.toString();
}
}