spring security oauth2.0 根据token信息获取用户信息

项目场景：

既然前面有说到spring security 是如何验证当前用户以及获取到当前用户信息，哪么spring security auth2.0又是如何验证当前用户信息的呢？

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技术详解：

spring security auth2.0验证用户信息其实更加简单，具体的逻辑就在OAuth2AuthenticationProcessingFilter，我们先一起看看OAuth2AuthenticationProcessingFilter的源码吧.

OAuth2AuthenticationProcessingFilter.java

public class OAuth2AuthenticationProcessingFilter implements Filter, InitializingBean {
    
    
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException,
			ServletException {

		final boolean debug = logger.isDebugEnabled();
		final HttpServletRequest request = (HttpServletRequest) req;
		final HttpServletResponse response = (HttpServletResponse) res;

		try {

			Authentication authentication = tokenExtractor.extract(request);
			
			if (authentication == null) {
				if (stateless && isAuthenticated()) {
					if (debug) {
						logger.debug("Clearing security context.");
					}
					SecurityContextHolder.clearContext();
				}
				if (debug) {
					logger.debug("No token in request, will continue chain.");
				}
			}
			else {
				request.setAttribute(OAuth2AuthenticationDetails.ACCESS_TOKEN_VALUE, authentication.getPrincipal());
				if (authentication instanceof AbstractAuthenticationToken) {
					AbstractAuthenticationToken needsDetails = (AbstractAuthenticationToken) authentication;
					needsDetails.setDetails(authenticationDetailsSource.buildDetails(request));
				}
				Authentication authResult = authenticationManager.authenticate(authentication);

				if (debug) {
					logger.debug("Authentication success: " + authResult);
				}

				eventPublisher.publishAuthenticationSuccess(authResult);
				SecurityContextHolder.getContext().setAuthentication(authResult);

			}
		}
		catch (OAuth2Exception failed) {
			SecurityContextHolder.clearContext();

			if (deb