1. 结论

**
AuthenticationEntryPoint 用来解决匿名用户访问无权限资源时的异常
AccessDeineHandler 用来解决认证过的用户访问无权限资源时的异常

2. AuthenticationEntryPoint

AuthenticationEntryPoint 是 Spring Security Web 一个概念模型接口，顾名思义，他所建模的概念是：“认证入口点”。
它在用户请求处理过程中遇到认证异常时，被 ExceptionTranslationFilter 用于开启特定认证方案 (authentication schema) 的认证流程。
该接口只定义了一个方法 :

void commence(HttpServletRequest request, HttpServletResponse response,
            AuthenticationException authException) throws IOException, ServletException;

这里参数 request 是遇到了认证异常 authException 用户请求，response 是将要返回给客户的相应，方法 commence 实现，也就是相应的认证方案逻辑会修改 response 并返回给用户引导用户进入认证流程。
当用户请求了一个受保护的资源，但是用户没有通过认证，那么抛出异常，AuthenticationEntryPoint.Commence(..)就会被调用。这个对应的代码在ExceptionTranslationFilter中，如下，当ExceptionTranslationFilter catch到异常后，就会间接调用AuthenticationEntryPoint。


public class ExceptionTranslationFilter extends GenericFilterBean {
    private AuthenticationEntryPoint authenticationEntryPoint;
......
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)res;
        try {
            chain.doFilter(request, response);
            this.logger.debug("Chain processed normally");
        } catch (IOException var9) {
            throw var9;
        } catch (Exception var10) {
            ......
            this.handleSpringSecurityException(request, response, chain, (RuntimeException)ase);
        }
    }
    private void handleSpringSecurityException(HttpServletRequest request, HttpServletResponse response, FilterChain chain, RuntimeException exception) throws IOException, ServletException {
        ......
        this.sendStartAuthentication(request, response, chain, (AuthenticationException)exception);
        ......
    }
    protected void sendStartAuthentication(HttpServletRequest request, HttpServletResponse response, FilterChain chain, AuthenticationException reason) throws ServletException, IOException {
        SecurityContextHolder.getContext().setAuthentication((Authentication)null);
        this.requestCache.saveRequest(request, response);
        this.logger.debug("Calling Authentication entry point.");
        this.authenticationEntryPoint.commence(request, response, reason);
    }
......

匿名用户访问某个接口时

/**
 * 认证失败处理类 返回未授权
 * 用来解决匿名用户访问无权限资源时的异常
 */
@Component
public class CustomAuthenticationEntryPoint implements AuthenticationEntryPoint, Serializable {
    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException e)
            throws IOException {
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/javascript;charset=utf-8");
        response.getWriter().print(JSONObject.toJSONString(RestMsg.error("没有访问权限!")));
    }
}

3. AccessDeniedHandler

AccessDeniedHandler 仅适用于已通过身份验证的用户。未经身份验证的用户的默认行为是重定向到登录页面（或适用于正在使用的身份验证机制的任何内容）。

已经授权但是没有访问权限

/**
 * 认证失败处理类 返回未授权
 * 用来解决认证过的用户访问无权限资源时的异常
 */
@Component
public class CustomAccessDeniedHandler implements AccessDeniedHandler {
    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response,
            AccessDeniedException accessDeniedException) throws IOException, ServletException {
        response.setCharacterEncoding("utf-8");
        response.setContentType("text/javascript;charset=utf-8");
        response.getWriter().print(JSONObject.toJSONString(RestMsg.error("没有访问权限!")));
    }
}

4. 配置

public class SecurityConfig extends WebSecurityConfigurerAdapter {
    @Autowired
    private CustomAuthenticationEntryPoint authenticationEntryPoint;
    @Autowired
    private CustomAccessDeniedHandler customAccessDeniedHandler;
    // 省略部分代码
    @Override
    protected void configure(HttpSecurity httpSecurity) throws Exception {
         httpSecurity
                // 认证失败处理类
                .exceptionHandling()
                    .authenticationEntryPoint(authenticationEntryPoint)
                    .accessDeniedHandler(customAccessDeniedHandler);               
    }
    // 省略部分代码
}

框架