springboot 中拦截器的使用

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第一步：创建一个实现 HandlerInterceptor 的类。

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  ==============");    }}

说明：
1. preHandle 表示方法请求前的处理，若其返回值为FALSE，就中断请求目标方法了，只有返回值为TRUE时才继续执行方法内容。
2. postHandle 是在目标方法执行完之后执行的。

第二步：注册拦截器。创建一个配置类并继承 WebMvcConfigurerAdapter。重写 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;@Configurationpublic class WebConfig extends WebMvcConfigurerAdapter{    public void addInterceptors(InterceptorRegistry registry) {        registry.addInterceptor(new WebInterceptor());        System.out.println("===========   拦截器注册完毕   ===========");    }}

第三步：编写普通的controller 和方法。

import org.springframework.ui.Model;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RestController;@RestControllerpublic class WebController {    @RequestMapping("/interceptor")    public String interceptor(Model model) {        model.addAttribute("hello", "hello");        System.out.println("model : " + model);        return "inderceptor";    }}

最后：执行controller 方法即可在控制台看到效果。

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

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