SpringBoot 过滤器与 * 实例演示

   SpringBoot中的过滤器 * 操作与springmvc中的几乎一样所以这里也不过多介绍了，下面举两个简单的栗子演示一下

1、过滤器        

1 创建过滤器类LoginFilter,实现servlet包下的Filter接口（包不要导错），加入注解WebFilter

package com.example.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebFilter(urlPatterns = "/filter/*")
public class LoginFilter implements Filter {
   @Override
   public void init(FilterConfig filterConfig) throws ServletException {
       System.out.println("初始化 * ");
   }

@Override
   public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
       System.out.println("LoginFilter");
       HttpServletRequest request = (HttpServletRequest)servletRequest;
       HttpServletResponse response = (HttpServletResponse)servletResponse;
       //放行
       filterChain.doFilter(request,response);
   }

@Override
   public void destroy() {
       System.out.println(" * 销毁");
   }
}

     2 创建测试类LoginCotroller

package com.example.controller;

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

@RestController
@RequestMapping("/filter")
public class FilterController {

@RequestMapping("/login")
   public String login(){
       System.out.println("登录");
       return "login";
   }

}

      3 在启动类上加注解

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan
//Servlet、Filter、Listener可以直接通过@WebServlet、@WebFilter、@WebListener注解自动注册
public class DemoApplication {

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

}

  4 启动测试，启动的时候可以看到Filter调用init方法初始化

 接着访问可以看到页面输出

 控制台打印出 * 中的语句

2、 *        

1 创建自定义 *

package com.example.interceptor;

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

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

public class MyInterceptor implements HandlerInterceptor {
  //进入controller方法之前调用的
   @Override
   public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
       System.out.println("preHandle");
       return true;//true表示放行 false表示不放行
   }
   //调用完controller之后，视图渲染层之前
   @Override
   public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
       System.out.println("postHandle");
   }
   //页面跳转之后，整个流程执行之后，一般用于资源的清理
   @Override
   public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
       System.out.println("afterCompletion");
   }
}

      2 创建 * 配置类，注意要加上配置类的注解

package com.example.config;

import com.example.interceptor.MyInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class MyInterceptorConfig implements WebMvcConfigurer {

@Override
   public void addInterceptors(InterceptorRegistry registry) {
       //设置 * 并指定拦截路径
       registry.addInterceptor(new MyInterceptor()).addPathPatterns("/interceptor/*");
       //registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");//拦截所有
       //registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**").excludePathPatterns("/test");//指定不拦截

//添加自定义 *
       WebMvcConfigurer.super.addInterceptors(registry);
   }
}

        3 创建LoginController测试类

package com.example.controller;

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

@RestController
@RequestMapping("/interceptor")
public class InterceptorController {
   @RequestMapping("login")
   public String login(){
       System.out.println("Interceptor-Login");
       return "login";
   }
}

      4 运行访问，查看效果

控制台输出如下

来源：https://blog.csdn.net/layonly/article/details/121390506