springboot拦截器的使用与配置

1. 自定义拦截器

import lombok.extern.slf4j.Slf4j;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@Component
@Slf4j
//HandlerInterceptor:所有自定义拦截器或springboot提供的拦截器的鼻祖
public class DemoInterceptor implements HandlerInterceptor {
    //preHandle：当某个URL已经匹配到对应的Controller中的某个方法，且在这个方法执行之前执行。
    //如果返回true，则放行；返回false,则不会向后执行
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info("preHandle");
        log.info("preHandle--URI" + request.getRequestURI());
        return true;
    }
    //postHandle：当某个URL已经匹配到对应的Controller中的某个方法，且在这个方法执行完成之后执行，但是在DispatcherServlet视图渲染之前。
    //在这个方法中有个ModelAndView参数，可以在此做一些修改动作。
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
        log.info("postHandle");
        log.info("postHandle--URI" + request.getRequestURI());
        response.setCharacterEncoding("UTF-8");
    }

    //afterCompletion：该方法是在整个请求处理完成后（包括视图渲染）执行，这时做一些资源的清理工作。
    //这个方法只有在preHandler()被成功执行后并且返回true才会被执行。
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
        log.info("afterCompletion");
        log.info("afterCompletion--URI" + request.getRequestURI());
    }

2. 配置拦截器

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.StringHttpMessageConverter;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

import java.nio.charset.Charset;
import java.util.List;

public class WebMvcConfig extends WebMvcConfigurationSupport {
    @Autowired
    private DemoInterceptor demoInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(demoInterceptor).addPathPatterns("/**")
                .excludePathPatterns("/testUser/login");
    }

    //解决添加拦截器之后的乱码问题
    @Bean
    protected void configureMessageConverters(List> converters) {
        super.configureMessageConverters(converters);
        converters.add(messageConverter());
    }

    public HttpMessageConverter messageConverter(){
        return new StringHttpMessageConverter(Charset.forName("UTF-8"));
    }