文章首发于：clawhub.club

需求：个别接口，需要授权码才可以使用，所以要配置拦截器。

首先要实现WebMvcConfigurer接口，Spring的WebMvcConfigurer接口提供了很多方法让我们来定制SpringMVC的配置。
如图：
WebMvcConfigurer.png

实现代码：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
@Configuration
public class WebConfigurer implements WebMvcConfigurer {

    /**
     * The Auth code interceptor.
     */
    @Autowired
    private AuthCodeInterceptor authCodeInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(authCodeInterceptor).addPathPatterns("/xxxx");
    }
}

从代码中可以看到注入了一个拦截器：AuthCodeInterceptor
其代码实现：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
@Component
public class AuthCodeInterceptor implements HandlerInterceptor {

    /**
     * The Auth code service.
     */
    @Autowired
    private AuthCodeService authCodeService;

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws IOException {

        //从请求中获取请求体中的authCode,并校验
        int flag = authCodeService.checkAuthCodeCore(request.getParameter("authCode"));
        String reply;
        if (flag == 0) {
            //授权码有效
            return true;
        } else if (flag == 1) {
            reply = "{\"code\":\"1\",\"msg\":\"授权码不存在\"}";
        } else if (flag == 2) {
            reply = "{\"code\":\"2\",\"msg\":\"授权次数不足\"}";
        } else {
            reply = "{\"code\":\"-2\",\"msg\":\"其他错误\"}";
        }
        response.setCharacterEncoding("UTF-8");
        response.setContentType("application/json;charset=utf-8");
        response.getWriter().write(reply);
        return false;
    }

}

以上就简单实现了拦截特定接口，获取请求参数，之后判断授权码是否可用，可用时，通过，不可用拒绝，并向response中写入响应信息。

关键方法：添加Spring MVC生命周期拦截器，用于控制器方法调用的预处理和后处理。拦截器可以注册为应用于所有请求，也可以限制为URL模式的子集。在这里注册的拦截器只适用于控制器，而不适用于资源处理程序请求。要拦截对静态资源的请求，可以声明MappedInterceptor bean 或者 通过扩展WebMvcConfigurationSupport切换到高级配置模式，然后override resourceHandlerMapping

1
2
3
4
5
6
7
8
9
10
11
12
13
14
/**
	 * Add Spring MVC lifecycle interceptors for pre- and post-processing of
	 * controller method invocations. Interceptors can be registered to apply
	 * to all requests or be limited to a subset of URL patterns.
	 * <p><strong>Note</strong> that interceptors registered here only apply to
	 * controllers and not to resource handler requests. To intercept requests for
	 * static resources either declare a
	 * {@link org.springframework.web.servlet.handler.MappedInterceptor MappedInterceptor}
	 * bean or switch to advanced configuration mode by extending
	 * {@link org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport
	 * WebMvcConfigurationSupport} and then override {@code resourceHandlerMapping}.
	 */
	default void addInterceptors(InterceptorRegistry registry) {
	}