• 概括
• 环境
• 配置拦截器
  • 单个拦截器
  • 多个拦截器
• 源码

概括

pringMVC中的拦截器用于拦截控制器方法的执行

环境

 
        
        
            org.springframework
            spring-webmvc
            5.3.1
        
        
        
            ch.qos.logback
            logback-classic
            1.2.3
        
        
        
            javax.servlet
            javax.servlet-api
            3.1.0
            provided
        
        
        
            org.thymeleaf
            thymeleaf-spring5
            3.0.12.RELEASE
        

        
            com.fasterxml.jackson.core
            jackson-databind
            2.12.1
        

    

<?xml version="1.0" encoding="UTF-8"?>


    
    

    
    
        
        
        
            
                
                    
                        
                        
                        
                        
                        
                        
                    
                
            
        
    

    
    

    
        
            
            
                
                
                    
                        text/html
                        application/json
                    
                
            
        
    

<?xml version="1.0" encoding="UTF-8"?>


    
        CharacterEncodingFilter
        org.springframework.web.filter.CharacterEncodingFilter
        
            encoding
            UTF-8
        
        
            forceResponseEncoding
            true
        
    

    
        CharacterEncodingFilter
        /*
    

    
        DispatcherServlet
        org.springframework.web.servlet.DispatcherServlet
        
            contextConfigLocation
            classpath:springMVC.xml
        
        1
    

    
        DispatcherServlet
        /
    

配置拦截器

单个拦截器

package com.fly.Interceptors;

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;

/**
 * @author 26414
 */
@Component
public class FirstInterceptor implements HandlerInterceptor {


  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    System.out.println("FirstInterceptor==============preHandle");
    return true;
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    System.out.println("FirstInterceptor==============postHandle");
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    System.out.println("FirstInterceptor==============afterCompletion");
  }
}

在配置文件中进行配置

package com.fly.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

/**
 * @author 26414
 */
@Controller
public class InterceptorController {
  
  @RequestMapping("/testInterceptor")
  public String testInterceptor() {
    return "success";
  }
  
}

testInterceptor

success

多个拦截器

package com.fly.Interceptors;

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;

/**
 * @author 26414
 */
@Component
public class SecondInterceptor implements HandlerInterceptor{
  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
    System.out.println("SecondInterceptor==============preHandle");
    return true;
  }

  @Override
  public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    System.out.println("SecondInterceptor==============postHandle");
  }

  @Override
  public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    System.out.println("SecondInterceptor==============afterCompletion");
  }
}

源码

在testInterceptor方法上打断点，以debug模式启动服务器

如果有一个拦截器返回false，interceptorIndex的最大值为返回false的前一个i

1：若每个拦截器的preHandle()都返回true此时多个拦截器的执行顺序和拦截器在SpringMVC的配置文件的配置顺序有关，preHandle()会按照配置的顺序执行，而postHandle()和afterComplation()会按照配置的反序执行。
2：若某个拦截器的preHandle()返回了falsepreHandle()返回false和它之前的拦截器的preHandle()都会执行，postHandle()都不执行，返回false的拦截器之前的拦截器的afterComplation()会执行