SpringMVC拦截器的应用

一、作用

  1. 对请求进行预处理和后处理;
  2. 使用场景:
    • 登录验证,判断用户是否登录
    • 权限验证,判断用户是否有权限访问资源,如校验token
    • 日志记录,记录请求操作日志(用户ip,访问时间等),以便统计请求访问量
    • 处理cookie、本地化、国际化、主题等
    • 性能监控,监控请求处理时长等。

SpringMVC拦截器的应用

二、实现

  1. 继承HandlerInterceptorAdapter抽象类或者实现HandlerInterceptor接口;
  2. 示例:
public class InterceptorDemo extends HandlerInterceptorAdapter {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        StringBuffer requestURL = httpServletRequest.getRequestURL();
        System.out.println("前置拦截器1 preHandle: 请求的uri为:"+requestURL.toString());
        return true;
    }
    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        System.out.println("拦截器1 postHandle: ");
    }
    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("拦截器1 afterCompletion: ");
    }
}

四大方法:

preHandle是在请求controllor前调用,返回true才向后调用其它方法,

postHandler在调用Controller方法之后、视图渲染之前调用,

afterCompletion是在渲染视图完成之后使用,

afterConcurrentHandlingStarted方法用来处理异步请求。

三、注册

  • 通过@Component 或者 @Configuration将Bean注册到spring容器中
@Configuration
public class InterceptorConfig implements WebMvcConfigurer{

@Override
public void addInterceptors(InterceptorRegistry registry) {
        //注册TestInterceptor拦截器
        InterceptorRegistration registration = registry.addInterceptor(new InterceptorDemo());
        registration.addPathPatterns("/**");                      //所有路径都被拦截
        registration.excludePathPatterns(                         //添加不拦截路径
                                         "你的登陆路径",            //登录
                                         "/**/*.html",            //html静态资源
                                         "/**/*.js",              //js静态资源
                                         "/**/*.css",             //css静态资源
                                         "/**/*.woff",
                                         "/**/*.ttf"
                                         );    
    }
 }
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