spring security-源码流程分析（五）-oauth默认请求地址（/oauth/token）是如何生效的？

spring security经常在项目中用到，但是平常只是简单的使用肯定是不够的，我们需要了解深层次的东西，才能在使用的过程中不畏惧，本次打算从demo入手，跟踪源码，剖析security内在

一、@FrameworkEndpoint注解的作用

1、在之前的文章中我们看到AuthorizationServerEndpointsConfiguration配置中配置了AuthorizationEndpoint和TokenEndpoint等，他们都是继承自AbstractEndpoint

2、AuthorizationServerEndpointsConfiguration中创建了FrameworkEndpointHandlerMapping


这个RequestMappingHandlerMapping大家应该比较熟悉了，是mvc中的加载handler的类

现在我们看下FrameworkEndpointHandlerMapping的isHandler方法

至此应该清楚了，就是类上注解@FrameworkEndpoint的存在，将各个AbstractEndpoint的方法加载到servlet中

二、oauth/token请求参数如何封装成了Principal

clent的认证我们上一篇文章中已经讲过了，现在我们继续剖析这个获取token的接口
首先我们倒推看下mvc中参数是如何解析并封装到方法中的

1、ServletRequestMethodArgumentResolver参数解析

@Nullable
	private Object resolveArgument(Class<?> paramType, HttpServletRequest request) throws IOException {
		if (HttpSession.class.isAssignableFrom(paramType)) {
			HttpSession session = request.getSession();
			if (session != null && !paramType.isInstance(session)) {
				throw new IllegalStateException(
						"Current session is not of type [" + paramType.getName() + "]: " + session);
			}
			return session;
		}
		...
		...
		//从request中获取principal
		else if (Principal.class.isAssignableFrom(paramType)) {
			Principal userPrincipal = request.getUserPrincipal();
			if (userPrincipal != null && !paramType.isInstance(userPrincipal)) {
				throw new IllegalStateException(
						"Current user principal is not of type [" + paramType.getName() + "]: " + userPrincipal);
			}
			return userPrincipal;
		}
		else if (HttpMethod.class == paramType) {
			return HttpMethod.resolve(request.getMethod());
		}
		...
	
		// Should never happen...
		throw new UnsupportedOperationException("Unknown parameter type: " + paramType.getName());
	}

从request中获取principal，此时的request的是

2、SecurityContextHolderAwareRequestFilter过滤器创建流程见下图

3、SecurityContextHolderAwareRequestFilter执行流程

小结

由于Servlet3SecurityContextHolderAwareRequestWrapper继承自SecurityContextHolderAwareRequestWrapper
回到参数解析流程，调用了request的getUserPrincipal方法，看下SecurityContextHolderAwareRequestWrapper的getUserPrincipal方法


至此返回了认证对象Authentication

三、grant过程

@RequestMapping(value = "/oauth/token", method=RequestMethod.POST)
	public ResponseEntity<OAuth2AccessToken> postAccessToken(Principal principal, @RequestParam
	Map<String, String> parameters) throws HttpRequestMethodNotSupportedException {

		if (!(principal instanceof Authentication)) {
			throw new InsufficientAuthenticationException(
					"There is no client authentication. Try adding an appropriate authentication filter.");
		}

		String clientId = getClientId(principal);
		ClientDetails authenticatedClient = getClientDetailsService().loadClientByClientId(clientId);

		TokenRequest tokenRequest = getOAuth2RequestFactory().createTokenRequest(parameters, authenticatedClient);

		if (clientId != null && !clientId.equals("")) {

			if (!clientId.equals(tokenRequest.getClientId())) {
		
				throw new InvalidClientException("Given client ID does not match authenticated client");
			}
		}
		...
		...
		//获取tokenGranter
		OAuth2AccessToken token = getTokenGranter().grant(tokenRequest.getGrantType(), tokenRequest);
		if (token == null) {
			throw new UnsupportedGrantTypeException("Unsupported grant type: " + tokenRequest.getGrantType());
		}

		return getResponse(token);

	}

此时的tokenGranter是AuthorizationServerEndpointsConfigurer的tokenGranter创建的匿名对象

默认5种授权类型（授权码模式（authorization_code）、刷新令牌（refresh_token）、简化模式（implicit）、客户端模式（client credentials）、密码模式（password）