SpringBoot和SpringSecurity處理Ajax登錄請求的問題

<dependency>
 <groupId>org.mybatis.spring.boot</groupId>
 <artifactId>mybatis-spring-boot-starter</artifactId>
 <version>1.3.1</version>
</dependency>
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-security</artifactId>
</dependency>
<dependency>
 <groupId>org.springframework.boot</groupId>
 <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
 <groupId>mysql</groupId>
 <artifactId>mysql-connector-java</artifactId>
 <scope>runtime</scope>
</dependency>
<dependency>
 <groupId>commons-codec</groupId>
 <artifactId>commons-codec</artifactId>
 <version>1.11</version>
</dependency>

spring.datasource.url=jdbc:mysql:///vueblog
spring.datasource.username=root
spring.datasource.password=123

public class User implements UserDetails {
 private Long id;
 private String username;
 private String password;
 private String nickname;
 private boolean enabled;
 private List<Role> roles;
 @Override
 public boolean isAccountNonExpired() {
 return true;
 }
 @Override
 public boolean isAccountNonLocked() {
 return true;
 }
 @Override
 public boolean isCredentialsNonExpired() {
 return true;
 }
 @Override
 public boolean isEnabled() {
 return enabled;
 }
 @Override
 public List<GrantedAuthority> getAuthorities() {
 List<GrantedAuthority> authorities = new ArrayList<>();
 for (Role role : roles) {
 authorities.add(new SimpleGrantedAuthority("ROLE_" + role.getName()));
 }
 return authorities;
 }
 //getter/setter省略...
}

@Service
public class UserService implements UserDetailsService {
 @Autowired
 UserMapper userMapper;
 @Autowired
 RolesMapper rolesMapper;
 @Override
 public UserDetails loadUserByUsername(String s) throws UsernameNotFoundException {
 User user = userMapper.loadUserByUsername(s);
 if (user == null) {
 //避免返回null，這里返回一個不含有任何值的User對象，在后期的密碼比對過程中一樣會驗證失敗
 return new User();
 }
 //查詢用戶的角色信息，并返回存入user中
 List<Role> roles = rolesMapper.getRolesByUid(user.getId());
 user.setRoles(roles);
 return user;
 }
}

@Configuration
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
 @Autowired
 UserService userService;
 @Override
 protected void configure(AuthenticationManagerBuilder auth) throws Exception {
 auth.userDetailsService(userService).passwordEncoder(new PasswordEncoder() {
 @Override
 public String encode(CharSequence charSequence) {
 return DigestUtils.md5DigestAsHex(charSequence.toString().getBytes());
 }
 /**
 * @param charSequence 明文
 * @param s 密文
 * @return
 */
 @Override
 public boolean matches(CharSequence charSequence, String s) {
 return s.equals(DigestUtils.md5DigestAsHex(charSequence.toString().getBytes()));
 }
 });
 }
 @Override
 protected void configure(HttpSecurity http) throws Exception {
 http.authorizeRequests()
 .antMatchers("/admin/**").hasRole("超級管理員")
 .anyRequest().authenticated()//其他的路徑都是登錄后即可訪問
 .and().formLogin().loginPage("/login_page").successHandler(new AuthenticationSuccessHandler() {
 @Override
 public void onAuthenticationSuccess(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Authentication authentication) throws IOException, ServletException {
 httpServletResponse.setContentType("application/json;charset=utf-8");
 PrintWriter out = httpServletResponse.getWriter();
 out.write("{\"status\":\"ok\",\"msg\":\"登錄成功\"}");
 out.flush();
 out.close();
 }
 })
 .failureHandler(new AuthenticationFailureHandler() {
 @Override
 public void onAuthenticationFailure(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, AuthenticationException e) throws IOException, ServletException {
 httpServletResponse.setContentType("application/json;charset=utf-8");
 PrintWriter out = httpServletResponse.getWriter();
 out.write("{\"status\":\"error\",\"msg\":\"登錄失敗\"}");
 out.flush();
 out.close();
 }
 }).loginProcessingUrl("/login")
 .usernameParameter("username").passwordParameter("password").permitAll()
 .and().logout().permitAll().and().csrf().disable();
 }
 @Override
 public void configure(WebSecurity web) throws Exception {
 web.ignoring().antMatchers("/reg");
 }
}

@RestController
public class LoginRegController {

 /**
 * 如果自動跳轉到這個頁面，說明用戶未登錄，返回相應的提示即可
 * <p>
 * 如果要支持表單登錄，可以在這個方法中判斷請求的類型，進而決定返回JSON還是HTML頁面
 *
 * @return
 */
 @RequestMapping("/login_page")
 public RespBean loginPage() {
 return new RespBean("error", "尚未登錄，請登錄!");
 }
}