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springboot(五)——springboot中的拦截器和过滤器小结

前言

关于过滤器Filter和拦截器Interceptor，大家都不会陌生，从一开始的servelet，到springmvc，再到现在的springboot，都有接触到，记得刚接触的时候，会容易弄混淆，想写这篇文章做个小的总结

拦截器和过滤器的异同

相同点
1. 都是aop编程思想的体现，可以在程序执行前后做一些操作，如权限操作，日志记录等
不同点：
1. Filter是Servlet规范中定义的，拦截器是Spring框架中的
2. 触发时机不一样，过滤器是在请求进入容器后，但请求进入servlet之前进行预处理的
3. 拦截器可以获取IOC容器中的各个bean，而过滤器就不行，拦截器归Spring管理

Springboot实现过滤器和拦截器

第一步：定义Filter

@Slf4j
public class TestFilter implements Filter {

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain)
            throws IOException, ServletException {
        log.info("TestFilter filter。。。。。。。。");
        filterChain.doFilter(servletRequest, servletResponse);
    }
}

第二步：注入springboot容器当中

@Configuration
public class FilterConfig {

    @Bean
    Filter testFilter(){
        return new TestFilter();
    }

    @Bean
    public FilterRegistrationBean<TestFilter> filterRegistrationBean1(){
        FilterRegistrationBean<TestFilter> filterRegistrationBean=new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter((TestFilter) testFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        //filterRegistrationBean.setOrder();多个filter的时候order的数值越小 则优先级越高
        return filterRegistrationBean;
    }
}

第三步：定义拦截器

@Slf4j
@Service(value = "testInterceptor")
public class TestInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("TestInterceptor preHandle....");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
        log.info("TestInterceptor postHandle....");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
        log.info("TestInterceptor afterCompletion....");
    }

}

第四步：加入springboot容器

@Configuration
public class InterceptorConfig implements WebMvcConfigurer {

    @Autowired
    TestInterceptor testInterceptor;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(testInterceptor)
                .addPathPatterns("/api/**");
    }
}

注意：这边用的springboot是2.0.x，采取的是直接实现WebMvcConfigurer，因为WebMvcConfigurerAdapter被标识了@Deprecated，就没有继承WebMvcConfigurerAdapter了

/** @deprecated */
@Deprecated
public abstract class WebMvcConfigurerAdapter implements WebMvcConfigurer {
    public WebMvcConfigurerAdapter() {
    }
}

第五步：还是启动之前的controller

@RestController
@RequestMapping("/api/test")
@Slf4j
public class TestController {

    @RequestMapping(value = "/hello")
    public String test() {
        log.info("test hello.............");
        return "SUCCESS";
    }

看到打印结果如下

2019-04-27/12:01:04.603||||||||^_^|[http-nio-8088-exec-1] INFO  com.stone.zplxjj.filter.TestFilter 22 - TestFilter filter。。。。。。。。
2019-04-27/12:01:04.612||||||||^_^|[http-nio-8088-exec-1] INFO  com.stone.zplxjj.interceptor.TestInterceptor 26 - TestInterceptor preHandle....
2019-04-27/12:01:04.634||||||||^_^|[http-nio-8088-exec-1] INFO  com.stone.zplxjj.interceptor.TestInterceptor 32 - TestInterceptor postHandle....
2019-04-27/12:01:04.634||||||||^_^|[http-nio-8088-exec-1] INFO  com.stone.zplxjj.interceptor.TestInterceptor 37 - TestInterceptor afterCompletion....