过滤器UsernamePasswordAuthenticationFilter用于处理登录

类图：https://www.malaoshi.top/upload/pic/1/login.png

public class UsernamePasswordAuthenticationFilter extends AbstractAuthenticationProcessingFilter {

    public static final String SPRING_SECURITY_FORM_USERNAME_KEY = "username";
    public static final String SPRING_SECURITY_FORM_PASSWORD_KEY = "password";
    //表单控件名
    private String usernameParameter = "username";
    private String passwordParameter = "password";
    private boolean postOnly = true;
    //匹配url：/login，并且是post方法
    public UsernamePasswordAuthenticationFilter() {
        super(new AntPathRequestMatcher("/login", "POST"));
    }

    public Authentication attemptAuthentication(HttpServletRequest request, HttpServletResponse response) throws AuthenticationException {
        //请求方法是post
        if (this.postOnly && !request.getMethod().equals("POST")) {
            throw new AuthenticationServiceException("Authentication method not supported: " + request.getMethod());
        } else {
            String username = this.obtainUsername(request);
            String password = this.obtainPassword(request);
            if (username == null) {
                username = "";
            }

            if (password == null) {
                password = "";
            }

            username = username.trim();
            UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(username, password);
            this.setDetails(request, authRequest);
            //进入authenticate()方法
            return this.getAuthenticationManager().authenticate(authRequest);
        }
    }

通过this.getAuthenticationManager().authenticate(authRequest);方法，来到下面接口：

public interface AuthenticationManager {
    Authentication authenticate(Authentication var1) throws AuthenticationException;
}

找到该接口的实现类ProviderManager的下面代码：

public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        Class<? extends Authentication> toTest = authentication.getClass();
        AuthenticationException lastException = null;
        AuthenticationException parentException = null;
        Authentication result = null;
        Authentication parentResult = null;
        boolean debug = logger.isDebugEnabled();
        Iterator var8 = this.getProviders().iterator();

        while(var8.hasNext()) {
            AuthenticationProvider provider = (AuthenticationProvider)var8.next();
            if (provider.supports(toTest)) {
                if (debug) {
                    logger.debug("Authentication attempt using " + provider.getClass().getName());
                }

                try {
                    //通过该方法找到AuthenticationProvider接口
                    result = provider.authenticate(authentication);
                    if (result != null) {
                        this.copyDetails(authentication, result);
                        break;
                    }
                } catch (InternalAuthenticationServiceException | AccountStatusException var13) {
                    this.prepareException(var13, authentication);
                    throw var13;
                } catch (AuthenticationException var14) {
                    lastException = var14;
                }
            }
        }

通过接口找到类AbstractUserDetailsAuthenticationProvider，关键代码如下：

public Authentication authenticate(Authentication authentication) throws AuthenticationException {
        Assert.isInstanceOf(UsernamePasswordAuthenticationToken.class, authentication, () -> {
            return this.messages.getMessage("AbstractUserDetailsAuthenticationProvider.onlySupports", "Only UsernamePasswordAuthenticationToken is supported");
        });
        String username = authentication.getPrincipal() == null ? "NONE_PROVIDED" : authentication.getName();
        boolean cacheWasUsed = true;
        UserDetails user = this.userCache.getUserFromCache(username);
        if (user == null) {
            cacheWasUsed = false;

            try {
                //找到该方法，通过该方法，找到类DaoAuthenticationProvider
                user = this.retrieveUser(username, (UsernamePasswordAuthenticationToken)authentication);
            } catch (UsernameNotFoundException var6) {
                this.logger.debug("User '" + username + "' not found");
                if (this.hideUserNotFoundExceptions) {
                    throw new BadCredentialsException(this.messages.getMessage("AbstractUserDetailsAuthenticationProvider.badCredentials", "Bad credentials"));
                }

                throw var6;
            }

找到其子类DaoAuthenticationProvider的retrieveUser方法：

    protected final UserDetails retrieveUser(String username, UsernamePasswordAuthenticationToken authentication) throws AuthenticationException {
        this.prepareTimingAttackProtection();

        try {
            //通过loadUserByUsername()找到UserDetailsService接口
            UserDetails loadedUser = this.getUserDetailsService().loadUserByUsername(username);
            if (loadedUser == null) {
                throw new InternalAuthenticationServiceException("UserDetailsService returned null, which is an interface contract violation");
            } else {
                return loadedUser;
            }
        } catch (UsernameNotFoundException var4) {
            this.mitigateAgainstTimingAttack(authentication);
            throw var4;
        } catch (InternalAuthenticationServiceException var5) {
            throw var5;
        } catch (Exception var6) {
            throw new InternalAuthenticationServiceException(var6.getMessage(), var6);
        }
    }

接口UserDetails的实现类，用于封装登录用户信息
接口UserDetailsService的实现类，实现登录功能

原文出处：/show_1EF60YyrM4Eq.html