第一步：建立一個實現 HandlerInterceptor 的類。

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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

public class WebInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        System.out.println("==============  request before  ==============");
        return true;
    }

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

    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("==============  request completion  ==============");
    }
}
 

說明： 1. preHandle 表示方法請求前的處理，若其返回值為FALSE，就中斷請求目標方法了，只有返回值為TRUE時才繼續執行方法內容。 2. postHandle 是在目標方法執行完之後執行的。

第二步：註冊攔截器。建立一個配置類並繼承 WebMvcConfigurerAdapter。重寫 addInterceptors 方法。

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter{

    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new WebInterceptor());
        System.out.println("===========   攔截器註冊完畢   ===========");
    }

}
 

第三步：編寫普通的controller 和方法。

import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class WebController {

    @RequestMapping("/interceptor")
    public String interceptor(Model model) {
        model.addAttribute("hello", "hello");
        System.out.println("model : " + model);
        return "inderceptor";
    }
}
 

最後：執行controller 方法即可在控制檯看到效果。

==============  request before  ==============
model : {hello=hello}
==============  request  ==============
==============  request completion==============