springMVC原始碼分析--攔截器HandlerExecutionChain(三)
阿新 • • 發佈:2019-01-06
上一篇部落格springMVC原始碼分析--HandlerInterceptor攔截器呼叫過程(二)中我們介紹了HandlerInterceptor的執行呼叫地方,最終HandlerInterceptor呼叫的地方是在HandlerExecutionChain中,接下來我們就介紹一下HandlerExecutionChain。HandlerExecutionChain有3個變數:
Object handler;不做過多介紹,儲存的物件是HandlerMethod
HandlerInterceptor[] interceptors :所有的HandlerInterceptor的陣列
List<HandlerInterceptor> interceptorList:所有的HandlerInterceptor的連結串列
之前的部落格中我們已經介紹了HandlerExecutionChain中執行HandlerInterceptor方法的函式
執行HandlerInterceptor的preHandler方法
執行HandlerInterceptor實現類的postHandle函式/** * 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. */ //依次執行HandlerInterceptor實現類的preHandle函式 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; }
執行HandlerInterceptor實現類的afterCompletion函式//依次執行HandlerInterceptor實現類的postHandle函式 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); } } }
//依次執行HandlerInterceptor實現類的postHandle函式
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);
}
}
}
執行HandlerInterceptor實現類的afterCompletion函式//依次執行HandlerInterceptor實現類的afterCompletion函式
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);
}
}
}
}
完整的HandlerExecutionChain的原始碼,主要就是以上幾個函式的操作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;
public HandlerExecutionChain(Object handler) {
this(handler, (HandlerInterceptor[]) null);
}
public HandlerExecutionChain(Object handler, HandlerInterceptor... interceptors) {
if (handler instanceof HandlerExecutionChain) {
HandlerExecutionChain originalChain = (HandlerExecutionChain) handler;
this.handler = originalChain.getHandler();
this.interceptorList = new ArrayList<HandlerInterceptor>();
CollectionUtils.mergeArrayIntoCollection(originalChain.getInterceptors(), this.interceptorList);
CollectionUtils.mergeArrayIntoCollection(interceptors, this.interceptorList);
}
else {
this.handler = handler;
this.interceptors = interceptors;
}
}
public Object getHandler() {
return this.handler;
}
public void addInterceptor(HandlerInterceptor interceptor) {
initInterceptorList().add(interceptor);
}
public void addInterceptors(HandlerInterceptor... interceptors) {
if (!ObjectUtils.isEmpty(interceptors)) {
initInterceptorList().addAll(Arrays.asList(interceptors));
}
}
private List<HandlerInterceptor> initInterceptorList() {
if (this.interceptorList == null) {
this.interceptorList = new ArrayList<HandlerInterceptor>();
if (this.interceptors != null) {
// An interceptor array specified through the constructor
this.interceptorList.addAll(Arrays.asList(this.interceptors));
}
}
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.
*/
//依次執行HandlerInterceptor實現類的preHandle函式
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.
*/
//依次執行HandlerInterceptor實現類的postHandle函式
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);
}
}
}
//依次執行HandlerInterceptor實現類的afterCompletion函式
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.
*/
//這個方法會在Controller方法非同步執行時開始執行
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() {
if (this.handler == null) {
return "HandlerExecutionChain with no handler";
}
StringBuilder sb = new StringBuilder();
sb.append("HandlerExecutionChain with handler [").append(this.handler).append("]");
if (!CollectionUtils.isEmpty(this.interceptorList)) {
sb.append(" and ").append(this.interceptorList.size()).append(" interceptor");
if (this.interceptorList.size() > 1) {
sb.append("s");
}
}
return sb.toString();
}
}