SpringBoot拦截器中Bean无法注入

因为拦截器在 Bean 初始化之前进行，所以在拦截器中无法像这样注入 Bean

@Autowired
private UserRepository userRepository;

方法一、

为了解决这个问题，我们在拦截器方法里，创建一个 BeanFactory 的实例，然后调用其 getBean() 方法来获取我们需要的 Bean 实例。

比如我们这里需要获取 userRepoditory 对象，可以这样（37-38行）

public class SessionInterceptor implements HandlerInterceptor {
@Autowired
private UserRepository userRepository;
/**
* 在请求处理之前进行调用（Controller方法调用之前）
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
return true;
}
/**
* 在请求处理之后调用，但是在视图被渲染之前（Controller方法调用之后）
*
* @param request
* @param response
* @param handler
* @param modelAndView
* @throws Exception
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
System.out.println("拦截了");
if(request.getSession().getAttribute("user") == null) {
//如果用户授权存在，添加Session
try {
SecurityContext securityContext = SecurityContextHolder.getContext();
Authentication authentication = securityContext.getAuthentication();
Object principal = authentication.getPrincipal();
if (principal != null && principal instanceof UserDetails) {
String username = ((UserDetails) principal).getUsername();
if(userRepository == null) {
BeanFactory factory = WebApplicationContextUtils.getRequiredWebApplicationContext(request.getServletContext());
userRepository = (UserRepository) factory.getBean("userRepository");
User user = userRepository.findByUsername(username);
request.getSession().setAttribute("user", user);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
/**
* 在整个请求调用之后被调用，也就是在 DispatcherServlet 渲染了对应的视图后执行（主要用于资源清理）
*
* @param request
* @param response
* @param handler
* @param ex
* @throws Exception
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
}
}

方法二、推荐

WebMvcConfig.java 监听器

@Configuration
public class WebMvcConfig implements WebMvcConfigurer {
@Bean
SessionInterceptor sessionInterceptor() {
return new SessionInterceptor();
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
//拦截器按照顺序执行
registry.addInterceptor(sessionInterceptor())
.addPathPatterns("/**")
.excludePathPatterns("/components/**","/css/**","/js/**","/img/**","/logout");
}
}

SessionInterceptor 拦截器

public class SessionInterceptor implements HandlerInterceptor {
@Autowired
private UserRepository userRepository;
@Autowired
private UserService userService;
/**
* 在请求处理之前进行调用（Controller方法调用之前）
*/
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
return true;
}
/**
* 在请求处理之后调用，但是在视图被渲染之前（Controller方法调用之后）
*
* @param request
* @param response
* @param handler
* @param modelAndView
* @throws Exception
*/
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
UserVO userSession = (UserVO) request.getSession().getAttribute("user");
if (userSession == null) {
//如果用户授权存在，添加Session
if (SecurityContextHolder.getContext().getAuthentication() != null && SecurityContextHolder.getContext().getAuthentication().isAuthenticated()
&& !SecurityContextHolder.getContext().getAuthentication().getPrincipal().toString().equals("anonymousUser")) {
User principal = (User) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
User user = userRepository.findByUsername(principal.getUsername());
UserVO userVO = userService.getUserVO(user);
request.getSession().setAttribute("user", userVO);
}
}
}
/**
* 在整个请求调用之后被调用，也就是在 DispatcherServlet 渲染了对应的视图后执行（主要用于资源清理）
*
* @param request
* @param response
* @param handler
* @param ex
* @throws Exception
*/
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
}
}