看一下HandlerInterceptor接口定義，關于具體的HandlerInterceptor說明大家可以看看源碼的官方doc說明，更加深入的了解這個接口，包括其一些實現(xiàn)：

HandlerInterceptor接口

preHandle：controller執(zhí)行之前調用
postHandle：controller執(zhí)行之后，且頁面渲染之前調用
afterCompletion：頁面渲染之后調用，一般用于資源清理操作

看一個demo，自己寫一個攔截器實現(xiàn)HandlerInterceptor，重寫三個方法，

package com.zhihao.miao;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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


public class LogHandlerInterceptor implements HandlerInterceptor {

    private Logger logger = LoggerFactory.getLogger(getClass());

    //請求執(zhí)行之前調用
    @Override
    public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception {
        System.out.println("==========preHandle==========" + handler.getClass());
        return true;
    }

    //請求之后，且頁面渲染之前調用
    @Override
    public void postHandle(HttpServletRequest request,HttpServletResponse response, Object handler,ModelAndView modelAndView) throws Exception {
       String UserAgent = request.getHeader("User-Agent");
       logger.info("UserAgent==="+UserAgent);
       String remoteIp = request.getRemoteHost()+","+request.getRequestURI();
       logger.info("remoteIp"+remoteIp);

    }

    //頁面渲染之后調用，一般用于資源清理操作
    @Override
    public void afterCompletion(HttpServletRequest request,HttpServletResponse response, Object handler, Exception ex)
            throws Exception {
        System.out.println("===========afterCompletion=========");
    }
}

寫一個類，繼承WebMvcConfigurerAdapter抽象類，然后重寫addInterceptors方法，并調用registry.addInterceptor注冊攔截器并將該類加入到spring容器中，

package com.zhihao.miao;

import org.springframework.boot.SpringBootConfiguration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@SpringBootConfiguration
public class WebConfiguration extends WebMvcConfigurerAdapter {

    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LogHandlerInterceptor());
    }
}

定義一個Controller進行測試：

package com.zhihao.miao;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

    private Logger logger = LoggerFactory.getLogger(getClass());

    @GetMapping("/user/home")
    public String home(){
        logger.info("user home");
        return "user home";
    }
}

啟動類啟動，

package com.zhihao.miao;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

訪問http://127.0.0.1:8080/user/home

總結：

編寫一個攔截器步驟：

• 寫一個攔截器，實現(xiàn)HandlerInterceptor接口
• 寫一個類，繼承WebMvcConfigurerAdapter抽象類，然后重寫addInterceptors方法，并調用registry.addInterceptor注冊自定義的攔截器。