spirng webUrl常见的集中问题_pathpatternscondition

1,当@PathVariable遇到/

常见的代码是如下图所示

@GetMapping("/hi1/{name}")
    public String hello(@PathVariable String name){
        return name;
    }

如果假设我们的name字段含有/字符是，会怎么样呢，比如lcy/sss,lcysss/,/lcysss是回事什么样子呢？当我们尝试之后就会发现，lcy/sss这种的会报错页面不存在，其他的都会返回lcysss。针对这种情况，我们看一下为什么回事这样？

我们先连接一下url匹配执行方法的相关问题，大致代码过程参考org.springframework.web.servlet.handler.AbstractHandlerMethodMapping#lookupHandlerMethod

protected HandlerMethod lookupHandlerMethod(String lookupPath, HttpServletRequest request) throws Exception {
		List<Match> matches = new ArrayList<>();
        //尝试按照url进行精确匹配
		List<T> directPathMatches = this.mappingRegistry.getMappingsByDirectPath(lookupPath);
		if (directPathMatches != null) {
         //精确匹配上，存储匹配结果
			addMatchingMappings(directPathMatches, matches, request);
		}
		if (matches.isEmpty()) {
         //如果没有匹配上，尝试根据请求来匹配
			addMatchingMappings(this.mappingRegistry.getRegistrations().keySet(), matches, request);
		}
		if (!matches.isEmpty()) {
			Match bestMatch = matches.get(0);
			if (matches.size() > 1) {
            //处理多个匹配的结果
				Comparator<Match> comparator = new MatchComparator(getMappingComparator(request));
				matches.sort(comparator);
				bestMatch = matches.get(0);
				if (logger.isTraceEnabled()) {
					logger.trace(matches.size() + " matching mappings: " + matches);
				}
				if (CorsUtils.isPreFlightRequest(request)) {
					for (Match match : matches) {
						if (match.hasCorsConfig()) {
							return PREFLIGHT_AMBIGUOUS_MATCH;
						}
					}
				}
				else {
					Match secondBestMatch = matches.get(1);
					if (comparator.compare(bestMatch, secondBestMatch) == 0) {
						Method m1 = bestMatch.getHandlerMethod().getMethod();
						Method m2 = secondBestMatch.getHandlerMethod().getMethod();
						String uri = request.getRequestURI();
						throw new IllegalStateException(
								"Ambiguous handler methods mapped for '" + uri + "': {" + m1 + ", " + m2 + "}");
					}
				}
			}
			request.setAttribute(BEST_MATCHING_HANDLER_ATTRIBUTE, bestMatch.getHandlerMethod());
			handleMatch(bestMatch.mapping, lookupPath, request);
			return bestMatch.getHandlerMethod();
		}
		else {
              //匹配不上，直接报错
			return handleNoMatch(this.mappingRegistry.getRegistrations().keySet(), lookupPath, request);
		}
	}

然后在仔细看第一步，根据path进行匹配查询

我们可以看到没有匹配上。

 在上面没有精确匹配上，则开始执行模匹配，待匹配的方法可以参考如图:

 显然。hi/{name}这个匹配方法已经出现了带匹配候选中，具体匹配的过程可以参考源码

org.springframework.web.servlet.mvc.method.RequestMappingInfo#getMatchingCondition

public RequestMappingInfo getMatchingCondition(HttpServletRequest request) {
       //检查http请求方法是否预定义的方法条件匹配		
RequestMethodsRequestCondition methods = this.methodsCondition.getMatchingCondition(request);
		if (methods == null) {
			return null;
		}
       //检查请求参数是否与定义的参数条件匹配
		ParamsRequestCondition params = this.paramsCondition.getMatchingCondition(request);
		if (params == null) {
			return null;
		}
       //检查请求头部是否与定义的参数条件匹配
		HeadersRequestCondition headers = this.headersCondition.getMatchingCondition(request);
		if (headers == null) {
			return null;
		}
        //代码检查请求的内容类型是否与定义的consumes条件匹配
		ConsumesRequestCondition consumes = this.consumesCondition.getMatchingCondition(request);
		if (consumes == null) {
			return null;
		}
        //检查可接收的内容类型是否与定义的produces条件匹配
		ProducesRequestCondition produces = this.producesCondition.getMatchingCondition(request);
		if (produces == null) {
			return null;
		}
		PathPatternsRequestCondition pathPatterns = null;
         //检查请求路径是否与定义的路径模式条件匹配
		if (this.pathPatternsCondition != null) {
			pathPatterns = this.pathPatternsCondition.getMatchingCondition(request);
			if (pathPatterns == null) {
				return null;
			}
		}
		PatternsRequestCondition patterns = null;
		if (this.patternsCondition != null) {
          //检查请求路径是否预定义的模式条件匹配
			patterns = this.patternsCondition.getMatchingCondition(request);
			if (patterns == null) {
				return null;
			}
		}
       //检查用户定义的任何自定义的模式条件匹配
		RequestConditionHolder custom = this.customConditionHolder.getMatchingCondition(request);
		if (custom == null) {
			return null;
		}
		return new RequestMappingInfo(this.name, pathPatterns, patterns,
				methods, params, headers, consumes, produces, custom, this.options);
	}

上述代码可以看到，匹配会查所有的的信息，如果有一个不匹配，则不符合

3.根据匹配情况返回结果

如果找到匹配的方法，则返回方法，如果没有，则返回null，同时为什么lcysss/,/lcysss没有报错，而是直接拿回了/。这里需要看一下匹配路径的方法：

org.springframework.web.servlet.mvc.condition.PatternsRequestCondition#getMatchingPatterns

public List<String> getMatchingPatterns(String lookupPath) {
   List<String> matches = null;
   for (String pattern : this.patterns) {
      String match = getMatchingPattern(pattern, lookupPath);
      if (match != null) {
         matches = (matches != null ? matches : new ArrayList<>());
         matches.add(match);
      }
   }
   if (matches == null) {
      return Collections.emptyList();
   }
   if (matches.size() > 1) {
      matches.sort(this.pathMatcher.getPatternComparator(lookupPath));
   }
   return matches;
}

private String getMatchingPattern(String pattern, String lookupPath) {
		if (pattern.equals(lookupPath)) {
			return pattern;
		}
		if (this.useSuffixPatternMatch) {
			if (!this.fileExtensions.isEmpty() && lookupPath.indexOf('.') != -1) {
				for (String extension : this.fileExtensions) {
					if (this.pathMatcher.match(pattern + extension, lookupPath)) {
						return pattern + extension;
					}
				}
			}
			else {
				boolean hasSuffix = pattern.indexOf('.') != -1;
				if (!hasSuffix && this.pathMatcher.match(pattern + ".*", lookupPath)) {
					return pattern + ".*";
				}
			}
		}
		if (this.pathMatcher.match(pattern, lookupPath)) {
			return pattern;
		}
		if (this.useTrailingSlashMatch) {
			if (!pattern.endsWith("/") && this.pathMatcher.match(pattern + "/", lookupPath)) {
				return pattern + "/";
			}
		}
		return null;
	}

最后会尝试加一下/进行匹配。