springboot 七-拦截器

拦截器

1、 鼻祖 HandlerInterceptor

2. PreHandle() 执行controller方法之前

3. postHandle()执行controller方法之后 DispatCherSevlet视图渲染之前 所以这个方法中有一个modelAndView参数 可以做一些修改

4. afterCompletion() 请求处理完成之后（包括DispatCherSevlet视图渲染之后） 有要求：preHandle()被成功执行且返回true

代码实战

1. 创建一个拦截器的类

package com.example.questionlist2.common;

import lombok.extern.slf4j.Slf4j;
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
//继承HandlerInterceptor  重新其中的拦截处理防范

public class myInterceptHandle implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        log.info(">>>拦截器>>>>>"+request.getRequestURI());
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

2. 对接口配置拦截

图片.png

package com.example.questionlist2.common;

import lombok.extern.slf4j.Slf4j;
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
//继承HandlerInterceptor  重新其中的拦截处理防范
public class myInterceptHandle implements HandlerInterceptor {

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

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
//        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
   log.info(">>> postHandle  <<<");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
//        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
        log.info(">>> afterCompletion  <<<");

    }
}

postman log

发现报错：
cannot deserialize from Object value (no delegate- or property-based Creator) at [
这个就是需要对error信息中提到的类 创建一个无参构造器

    public questionDto(){
        
    }

正确的拦截

1. 请求如下

curl --location --request POST 'http://localhost:8888/addQuestion3' \
--header 'Content-Type: application/json' \
--data-raw '{
    "questionType":"questionType1",
    "keyword":"keyword1",
    "questionName":"dedede  ",
    "dependOnQuestion":"dependOnQuestion2",
    "book":"book1"

} '

2. 然后结果是包含？？？ 说明响应body有问题

有乱码的结构

3. 对响应结果拦截并处理

这时候去父类中看下 哪个方法可以对响应结果进行配置

package com.example.questionlist2.common;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
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.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;

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

@Configuration
class myWebMvcConfig extends WebMvcConfigurationSupport {
    @Autowired
    private  myInterceptHandle myInterceptHandle;
    @Override
    //添加拦截器  先把我们创建的拦截器类加进来
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptHandle)
                .addPathPatterns("/**");
//                .excludePathPatterns("/addQuestion3");
    }

    @Override
    //这时候去父类中看下  哪个方法可以对响应结果进行配置
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        super.configureMessageConverters(converters);
        converters.add(setHttpMessageConverter());
    }
  public HttpMessageConverter<String> setHttpMessageConverter(){
        return new StringHttpMessageConverter(Charset.forName("utf-8"));
  }


}

图片.png