记录一下Spring Security Oauth2 认证（/oauth/token获取token）的源码出处

1.用户发起获取token请求（/oauth/token）：

map：
 Map<String, String> map = new HashMap<>();
            map.put("client_id", "aaa");
            map.put("client_secret", "aaa");
            map.put("grant_type", "password");
            map.put("username", username);
            map.put("loginMethod", loginUser.getLoginMethod());
            map.put("userType", loginUser.getUserType());
            map.put("password", pwd);
//发起获取token 请求：
"http://localhost:"+serverPort+"/oauth/token", RequestMethod.post, loginParams

2.此时oatuh的过滤器ClientCredentialsTokenEndpointFilter会去捕捉是否是""这个请求，如果是，则会

	@Override
	public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response)
			throws AuthenticationException, IOException, ServletException {

		if (allowOnlyPost && !"POST".equalsIgnoreCase(request.getMethod())) {
			throw new HttpRequestMethodNotSupportedException(request.getMethod(), new String[] { "POST" });
		}

		String clientId = request.getParameter("client_id");
		String clientSecret = request.getParameter("client_secret");

		// If the request is already authenticated we can assume that this
		// filter is not needed
		Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
		if (authentication != null && authentication.isAuthenticated()) {
			return authentication;
		}

		if (clientId == null) {
			throw new BadCredentialsException("No client credentials presented");
		}

		if (clientSecret == null) {
			clientSecret = "";
		}
		//在这里 获取封装Authentication 
		clientId = clientId.trim();
		UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(clientId,
				clientSecret);

		return this.getAuthenticationManager().authenticate(authRequest);

	}

3.以上全部通过会进入地址/oauth/token，即TokenEndpoint的postAccessToken方法中。

    @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.");
        } else {
            String clientId = this.getClientId(principal);
            ClientDetails authenticatedClient = this.getClientDetailsService().loadClientByClientId(clientId);
            TokenRequest tokenRequest = this.getOAuth2RequestFactory().createTokenRequest(parameters, authenticatedClient);
            if (clientId != null && !clientId.equals("") && !clientId.equals(tokenRequest.getClientId())) {
                throw new InvalidClientException("Given client ID does not match authenticated client");
            } else {
                if (authenticatedClient != null) {
                    this.oAuth2RequestValidator.validateScope(tokenRequest, authenticatedClient);
                }

                if (!StringUtils.hasText(tokenRequest.getGrantType())) {
                    throw new InvalidRequestException("Missing grant type");
                } else if (tokenRequest.getGrantType().equals("implicit")) {
                    throw new InvalidGrantException("Implicit grant type not supported from token endpoint");
                } else {
                    if (this.isAuthCodeRequest(parameters) && !tokenRequest.getScope().isEmpty()) {
                        this.logger.debug("Clearing scope of incoming token request");
                        tokenRequest.setScope(Collections.emptySet());
                    }

                    if (this.isRefreshTokenRequest(parameters)) {
                        tokenRequest.setScope(OAuth2Utils.parseParameterList((String)parameters.get("scope")));
                    }

                    OAuth2AccessToken token = this.getTokenGranter().grant(tokenRequest.getGrantType(), tokenRequest);
                    if (token == null) {
                        throw new UnsupportedGrantTypeException("Unsupported grant type: " + tokenRequest.getGrantType());
                    } else {
                        return this.getResponse(token);
                    }
                }
            }
        }
    }

可参考：https://blog.csdn.net/gangsijay888/article/details/81977796