应该将@ConditionalOnProperty注解移动到类中，而不是方法中。

@PropertySource(value = "classpath:securityConfig.properties", ignoreResourceNotFound = true)
@Controller
@ConditionalOnProperty(name = "auth.mode", havingValue = "fixed")
public class IndexController {
    ...
}

这将意味着整个控制器将不存在于应用程序上下文中，除非满足条件。

编辑@PreAuthorize注解以添加条件

@PropertySource(value = "classpath:securityConfig.properties", ignoreResourceNotFound = true)
@Controller
public class IndexController {
    private static final String LOGIN_PAGE           = "login";
    private static final String HOME_PAGE            = "home";
    private static final String LOBBY_PAGE           = "lobby";
    private static final String FORGOT_USER_PAGE     = "forgotUserName";
    private static final String FORGOT_PASSWORD_PAGE = "forgotPassWord";

    @Value("${auth.mode:fixed}")
    private String authenticationMode;

    public String getAuthenticationMode(){
         return this.authenticationMode;
    }

    @PreAuthorize("isAnonymous() AND this.getAuthenticationMode().equals(\"fixed\")")
    @RequestMapping(method = RequestMethod.GET, value = { "/login" })
    public String getIndexPage() {
        return LOGIN_PAGE;
    }

@ConditionalOnProperty可用作@Bean方法上的方法级别注解only，如（在配置类中）：

@Bean
  @ConditionalOnProperty(name = "myapp.feature.enabled", havingValue = "true")
  public MyFeature myFeature() {
      // create and return MyFeature instance
  }

我个人使用的@Value注解加载一个属性，然后根据属性值使用一个条件结构（if）。
例如：

@RestController
@RequestMapping("/my-endpoint")
public class MyController {

  @Value("${myapp.my-config-value}")
  private String myConfigValue;

  @GetMapping
  public String myMethod() {
    if ("disable".equals(myConfigValue)) {
      throw new IllegalStateException("This service is disabled.");
    }
    // if not disabled, do your stuff
    return myService.doStuff();
  }

}