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本文讲述一下如何自定义spring security的登录页，网上给的资料大多过时，而且是基于后端模板技术的，讲的不是太清晰，本文给出一个采用ajax的登录及返回的前后端分离方式。

ajax返回

总共需要处理3个地方，一个是异常的处理，需要兼容ajax请求，一个是成功返回的处理，一个是失败返回的处理。

ajax的异常处理

public class UnauthorizedEntryPoint implements AuthenticationEntryPoint {
    @Override
    public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException {
        if(isAjaxRequest(request)){
            response.sendError(HttpServletResponse.SC_UNAUTHORIZED,authException.getMessage());
        }else{
            response.sendRedirect("/login.html");
        }

    }

    public static boolean isAjaxRequest(HttpServletRequest request) {
        String ajaxFlag = request.getHeader("X-Requested-With");
        return ajaxFlag != null && "XMLHttpRequest".equals(ajaxFlag);
    }
}

这里我们自定义成功及失败的ajax返回，当然这里我们简单处理，只返回statusCode

AjaxAuthSuccessHandler

public class AjaxAuthSuccessHandler extends SimpleUrlAuthenticationSuccessHandler {
    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {
        response.setStatus(HttpServletResponse.SC_OK);
    }
}

AjaxAuthFailHandler

public class AjaxAuthFailHandler extends SimpleUrlAuthenticationFailureHandler {
    @Override
    public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response, AuthenticationException exception) throws IOException, ServletException {
        response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authentication failed");
    }
}

security配置

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        http
                .exceptionHandling().authenticationEntryPoint(new UnauthorizedEntryPoint())
                .and()
                .csrf().disable()
                .authorizeRequests()
                .antMatchers("/login","/css/**", "/js/**","/fonts/**").permitAll()
                .anyRequest().authenticated()
                .and()
                .formLogin()
                .loginPage("/login.html")
                .loginProcessingUrl("/login")
                .usernameParameter("name")
                .passwordParameter("password")
                .successHandler(new AjaxAuthSuccessHandler())
                .failureHandler(new AjaxAuthFailHandler())
                .permitAll()
                .and()
                .logout()
                .logoutUrl("/logout")
                .permitAll();
    }

    @Autowired
    public void configureGlobal(AuthenticationManagerBuilder auth) throws Exception {
        auth
                .inMemoryAuthentication()
                .withUser("admin").password("admin").roles("USER");
    }
}

这里有几个要注意的点：

• permitAll

这里要添加前端资源路径，以及登陆表单请求的接口地址/login

• loginPage

这里设置登录页面的地址，这里我们用静态页面，即static目录下的login.html

• ajax配置

将authenticationEntryPoint，successHandler，failureHandler设置为上面自定义的ajax处理类

登录页面

就是一个纯粹的html页面，其中登录按钮的ajax请求如下：

$.ajax({
            url: '/login',
            type: 'POST',
            data: "name="+name+"&password="+password,
            success: function (res, status) {
                window.location.href='/ok.html'
            },
            error: function (res, status) {
                dangerDialog(res.statusText);
            }
        });

这里是请求/login，也就是spring security会默认拦截的路径，不了解spring security的人可能会纳闷，我请求这个路径，但是工程里头没有定义/login的request mapping，不要紧么。下面来剖析一下。

spring security内置的各种filter：

这里我们要关注的就是这个UsernamePasswordAuthenticationFilter，顾名思义，它是filter，在执行/login请求的时候拦截，因而是不需要工程里头去定义login的request mapping的。

UsernamePasswordAuthenticationFilter

spring-security-web-4.2.3.RELEASE-sources.jar!/org/springframework/security/web/authentication/UsernamePasswordAuthenticationFilter.java

public class UsernamePasswordAuthenticationFilter extends
        AbstractAuthenticationProcessingFilter {

public Authentication attemptAuthentication(HttpServletRequest request,
            HttpServletResponse response) throws AuthenticationException {
        if (postOnly && !request.getMethod().equals("POST")) {
            throw new AuthenticationServiceException(
                    "Authentication method not supported: " + request.getMethod());
        }

        String username = obtainUsername(request);
        String password = obtainPassword(request);

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

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

        username = username.trim();

        UsernamePasswordAuthenticationToken authRequest = new UsernamePasswordAuthenticationToken(
                username, password);

        // Allow subclasses to set the "details" property
        setDetails(request, authRequest);

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

这里就是拦截，获取login.html提交的参数，然后交给authenticationManager去认证。之后就是走后续的filter，如果成功，则会进行相应的session配置。

doc

• spring security动态配置url权限
• Spring Security笔记：自定义Login/Logout Filter、AuthenticationProvider、AuthenticationToken