在前后端分离的状态下，传统的spring security认证模式也需要做一点改造，以适应ajax的前端访问模式

现在前后端分离的开发模式已经成为主流，好处不多说了，说说碰到的问题和坑。首先要解决的肯定是跨域问题，这个问题之前已经有讨论，请移步这里查看。另外一个问题是传统的spring security安全机制是基于页面跳转的，使用302重定向（认证成功跳转至之前访问的页面，认证失败或未认证跳转至系统设置的默认登陆页面）。传统应用这么弄没问题，但现在vue一般都是基于axios进行ajax访问，ajax请求是没法直接处理302跳转的（浏览器会直接处理跳转请求，ajax的callback拿到的是跳转后的返回页面，在spring security中就是登陆首页，不符合需求）。幸好spring security所有的流程都是可以自定义的，我们可以扩展一下各个环节的流程。spring boot版本为2.1.4.RELEASE，对应的spring security版本为5.1.5.RELEASE

核心配置类

WebSecurityConfig类配置如下

import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.annotation.Configuration;import org.springframework.http.HttpStatus;import org.springframework.security.authentication.AuthenticationDetailsSource;import org.springframework.security.authentication.AuthenticationProvider;import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;import org.springframework.security.config.annotation.web.builders.HttpSecurity;import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;import org.springframework.security.core.Authentication;import org.springframework.security.core.AuthenticationException;import org.springframework.security.core.context.SecurityContextHolder;import org.springframework.security.web.AuthenticationEntryPoint;import org.springframework.security.web.authentication.SimpleUrlAuthenticationFailureHandler;import org.springframework.security.web.authentication.SimpleUrlAuthenticationSuccessHandler;import org.springframework.security.web.authentication.WebAuthenticationDetails;import org.springframework.security.web.authentication.logout.SimpleUrlLogoutSuccessHandler;import com.bocsh.mer.security.MyUserDetailsService;@Configuration@EnableWebSecuritypublic class WebSecurityConfig extends WebSecurityConfigurerAdapter {        @Autowired    MyUserDetailsService myDetailService;        @Autowired    private AuthenticationDetailsSource<HttpServletRequest, WebAuthenticationDetails> authenticationDetailsSource;        protected Log log = LogFactory.getLog(this.getClass());        @Autowired    private AuthenticationProvider authenticationProvider;     @Override    protected void configure(AuthenticationManagerBuilder auth) throws Exception {                auth.authenticationProvider(authenticationProvider);    }        //定义登陆成功返回信息    private class AjaxAuthSuccessHandler extends SimpleUrlAuthenticationSuccessHandler {        @Override        public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {                        //User user = (User)SecurityContextHolder.getContext().getAuthentication().getPrincipal();            log.info("商户[" + SecurityContextHolder.getContext().getAuthentication().getPrincipal() +"]登陆成功！");            //登陆成功后移除session中验证码信息            request.getSession().removeAttribute("codeValue");            request.getSession().removeAttribute("codeTime");                        response.setContentType("application/json;charset=utf-8");            PrintWriter out = response.getWriter();            out.write("{\"status\":\"ok\",\"msg\":\"登录成功\"}");            out.flush();            out.close();        }    }        //定义登陆失败返回信息    private class AjaxAuthFailHandler extends SimpleUrlAuthenticationFailureHandler {        @Override        public void onAuthenticationFailure(HttpServletRequest request, HttpServletResponse response, AuthenticationException exception) throws IOException, ServletException {            //登陆失败后移除session中验证码信息            request.getSession().removeAttribute("codeValue");            request.getSession().removeAttribute("codeTime");                        response.setContentType("application/json;charset=utf-8");            response.setStatus(HttpStatus.UNAUTHORIZED.value());            PrintWriter out = response.getWriter();            out.write("{\"status\":\"error\",\"msg\":\"请检查用户名、密码或验证码是否正确\"}");            out.flush();            out.close();        }    }        //定义异常返回信息    public class UnauthorizedEntryPoint implements AuthenticationEntryPoint {        @Override        public void commence(HttpServletRequest request, HttpServletResponse response, AuthenticationException authException) throws IOException, ServletException {            response.sendError(HttpStatus.UNAUTHORIZED.value(),authException.getMessage());        }    }        //定义登出成功返回信息    private class AjaxLogoutSuccessHandler extends SimpleUrlLogoutSuccessHandler  {        public void onLogoutSuccess(HttpServletRequest request, HttpServletResponse response,                Authentication authentication) throws IOException, ServletException {            response.setContentType("application/json;charset=utf-8");            PrintWriter out = response.getWriter();            out.write("{\"status\":\"ok\",\"msg\":\"登出成功\"}");            out.flush();            out.close();        }    }        @Override    protected void configure(HttpSecurity http) throws Exception {        http        .exceptionHandling().authenticationEntryPoint(new UnauthorizedEntryPoint())        .and()        .csrf().disable()        .authorizeRequests()                               .antMatchers("/users/login_page","/users/captcha").permitAll()            .anyRequest().authenticated()            .and().formLogin().loginPage("/users/login_page")                              .successHandler(new AjaxAuthSuccessHandler())                              .failureHandler(new AjaxAuthFailHandler())                              .loginProcessingUrl("/login")                              .authenticationDetailsSource(authenticationDetailsSource)            .and()            .logout().logoutSuccessHandler(new AjaxLogoutSuccessHandler())            .logoutUrl("/logout");    }}

这里分别说明：configure方法配置整体的认证规则，即除了/users/login_page和/users/captcha这两个方式之外全部需要认证，同时在formLogin方法中设置了两个自定义的handler分别处理认证成功、认证失败的情况，这里我们设置直接返回json字符串，content-type设置为application/json;charset=utf-8，这样在认证完毕之后就不用自动302跳转了，而是交由axios框架来进行处理。

UnauthorizedEntryPoint定义了异常处理的逻辑，同理我们也是直接返回ajax信息而不做跳转。

axios相关配置

instance.interceptors.response.use(res => {      let { data } = res      this.destroy(url)      if (this.shade) {        Spin.hide()        Modal.success({          title: '操作成功'        })      }      console.log(res)      return data    }, error => {      console.log(error)      var code = error.response.status      if (code === 401) {        Cookies.remove(TOKEN_KEY)        window.location.href = '/login'        Message.error('未登录，或登录失效，请登录')      }

这里面我们定义了一个响应拦截器，在error情况下，判断若返回码为401（就是我们在spring security中自定义的handler的错误状态码），则自动跳转至登陆页面。这样实现了在会话失效的情况下，点击前端任意需要访问后端api的按钮，均会触发跳转登录首页的效果，符合我们的预期。实际情况中一般前端框架都会自己带一套基于cookies的认证机制，这里我们把cookies的失效时间可以设置的长一点（一般可以设为一天），以保障还是以后端会话的失效时间为准。

验证码处理

一般我们在处理用户登录，为安全考虑需要加入图形验证码。这里需要注意的一点是验证码也必须作为login这个action的处理参数传入，否则的话这个验证码只是做了前端页面验证，实际在处理login事件的时候是没有验证码的，这样就没有意义了。而spring security框架默认只能帮助我们处理用户名+密码的这样验证方式，这样就需要对认证方式进行扩展。

WebAuthenticationDetails

import javax.servlet.http.HttpServletRequest;import org.springframework.security.web.authentication.WebAuthenticationDetails;public class MyWebAuthenticationDetails extends WebAuthenticationDetails {    /**     *      */    private static final long serialVersionUID = 6975601077710753878L;        private String username;        private String password;        private String validcode;        private String sessionCodeValue;        private long sessionCodeTime;        public String getSessionCodeValue() {        return sessionCodeValue;    }    public void setSessionCodeValue(String sessionCodeValue) {        this.sessionCodeValue = sessionCodeValue;    }    public long getSessionCodeTime() {        return sessionCodeTime;    }    public void setSessionCodeTime(long sessionCodeTime) {        this.sessionCodeTime = sessionCodeTime;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }    public String getValidcode() {        return validcode;    }    public void setValidcode(String validcode) {        this.validcode = validcode;    }    public MyWebAuthenticationDetails(HttpServletRequest request) {        super(request);        username = request.getParameter("username");        password = request.getParameter("password");        validcode = request.getParameter("validateCode");        sessionCodeValue = (String)request.getSession().getAttribute("codeValue");        sessionCodeTime = (Long)request.getSession().getAttribute("codeTime");    }}

这边前三个参数是从页面的login请求中传过来的，后面两个参数是在页面上请求生成图片验证码的时候我们设置到session里面去，以便于后续的验证

AuthenticationDetailsSource

import javax.servlet.http.HttpServletRequest;import org.springframework.security.authentication.AuthenticationDetailsSource;import org.springframework.security.web.authentication.WebAuthenticationDetails;import org.springframework.stereotype.Component;@Componentpublic class MyAuthenticationDetailsSource implements AuthenticationDetailsSource<HttpServletRequest, WebAuthenticationDetails> {    @Override    public WebAuthenticationDetails buildDetails(HttpServletRequest context) {        return new MyWebAuthenticationDetails(context);    }}

这个类实现了一个自定义的接口，返回我们刚才定义的MyWebAuthenticationDetails资源

AuthenticationProvider

import java.util.ArrayList;import java.util.Collection;import java.util.Date;import org.apache.commons.logging.Log;import org.apache.commons.logging.LogFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.security.authentication.AuthenticationProvider;import org.springframework.security.authentication.BadCredentialsException;import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;import org.springframework.security.core.Authentication;import org.springframework.security.core.AuthenticationException;import org.springframework.security.core.GrantedAuthority;import org.springframework.security.core.authority.SimpleGrantedAuthority;import org.springframework.stereotype.Component;import com.bocsh.mer.service.MerchantService;@Componentpublic class MyAuthenticationProvider implements AuthenticationProvider {        protected Log log = LogFactory.getLog(this.getClass());        @Autowired    MerchantService ms;        @Override    public Authentication authenticate(Authentication authentication)             throws AuthenticationException {        log.info("now start custom authenticate process!");        MyWebAuthenticationDetails details = (MyWebAuthenticationDetails) authentication.getDetails();                  //校验码判断        if(!details.getValidcode().equals(details.getSessionCodeValue())) {            log.info("validate code error");            throw new BadCredentialsException("authenticate fail！");        }        //校验码有效期        if((new Date()).getTime() - details.getSessionCodeTime() > 60000) {            log.info("validate code expired!");            throw new BadCredentialsException("authenticate fail！");        }                //验密        String inpass="";        try {            inpass = ms.getPass(details.getUsername());        } catch (Exception e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        if(!inpass.equals(details.getPassword())) {            log.info("password error");            throw new BadCredentialsException("authenticate fail！");        }                            Collection<GrantedAuthority> auths=new ArrayList<GrantedAuthority>();         auths.add(new SimpleGrantedAuthority("ROLE_ADMIN"));        return new UsernamePasswordAuthenticationToken(details.getUsername(),details.getPassword(),auths);       }    @Override    public boolean supports(Class<?> authentication) {        return authentication.equals(UsernamePasswordAuthenticationToken.class);    }}

这里自定义了一个AuthenticationProvider来处理实际的认证业务逻辑，在这里可以方便的根据我们需要来进行自定义，我这边分别做了验证码校验、效期校验和验密，大家可以根据需要定制。认证成功就返回一个UsernamePasswordAuthenticationToken对象并配置好合适的权限（权限基于标准的RBAC模型，我这里为了讲解方便设置为ROLE_ADMIN，这里不展开讲了）。如果认证失败，只需要抛出一个异常（AuthenticationException的子类），这样spring security会自动找到失败页面进行返回，对应我们上面定义的AjaxAuthFailHandler这个类。

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