Spring Security3源码分析-BasicAuthenticationFilter分析

BasicAuthenticationFilter过滤器对应的类路径为
org.springframework.security.web.authentication.www.BasicAuthenticationFilter

Basic验证方式相比较而言用的不是太多。spring security也支持basic的方式，配置如下

<security:http auto-config="true">
    <!-- <security:form-login login-page="/login.jsp"/>-->
    <security:http-basic/>
    <security:logout logout-success-url="/login.jsp" invalidate-session="true"/>
    <security:intercept-url pattern="/login.jsp*" filters="none"/>
    <security:intercept-url pattern="/admin.jsp*" access="ROLE_ADMIN"/>
    <security:intercept-url pattern="/index.jsp*" access="ROLE_USER,ROLE_ADMIN"/>
    <security:intercept-url pattern="/**" access="ROLE_USER,ROLE_ADMIN"/>
</security:http>

如果选择basic方式，需要把form-login标签的定义给注释掉。

接下来看BasicAuthenticationFilter的执行过程

    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;
        //basic登录时，会产生Authorization的header信息
         //Authorization的值是Basic eXVxaW5nc29uZzox
        //eXVxaW5nc29uZzox是经过base编码的一串字符
        String header = request.getHeader("Authorization");
        if ((header != null) && header.startsWith("Basic ")) {
            byte[] base64Token = header.substring(6).getBytes("UTF-8");
            //经过base解码后，token值为username:password这种方式
            String token = new String(Base64.decode(base64Token), getCredentialsCharset(request));
            String username = "";
            String password = "";
            int delim = token.indexOf(":");

            if (delim != -1) {
                username = token.substring(0, delim);
                password = token.substring(delim + 1);
            }

            if (debug) {
                logger.debug("Basic Authentication Authorization header found for user '" + username + "'");
            }
            //下面的执行过程基本和login方式一样，认证、授权等过程
            if (authenticationIsRequired(username)) {
                UsernamePasswordAuthenticationToken authRequest =
                        new UsernamePasswordAuthenticationToken(username, password);
                authRequest.setDetails(authenticationDetailsSource.buildDetails(request));

                Authentication authResult;

                try {
                    authResult = authenticationManager.authenticate(authRequest);
                } catch (AuthenticationException failed) {
                    // Authentication failed
                    if (debug) {
                        logger.debug("Authentication request for user: " + username + " failed: " + failed.toString());
                    }

                    SecurityContextHolder.getContext().setAuthentication(null);

                    rememberMeServices.loginFail(request, response);

                    onUnsuccessfulAuthentication(request, response, failed);

                    if (ignoreFailure) {
                        chain.doFilter(request, response);
                    } else {
                        authenticationEntryPoint.commence(request, response, failed);
                    }

                    return;
                }

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

                SecurityContextHolder.getContext().setAuthentication(authResult);

                rememberMeServices.loginSuccess(request, response, authResult);

                onSuccessfulAuthentication(request, response, authResult);
            }
        }

        chain.doFilter(request, response);
    }