SpringBoot 过滤器与拦截器实例演示

来源：jb51　　时间：2021/11/23 16:30:30　　对本文有异议

???SpringBoot中的过滤器拦截器操作与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("初始化拦截器");
    }
 
    @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("拦截器销毁");
    }
}

?????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

?控制台打印出拦截器中的语句

2、拦截器 ? ? ? ?

1 创建自定义拦截器

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 创建拦截器配置类，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) {
        //设置拦截器并指定拦截路径
        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
 
        //添加自定义拦截器
        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";
    }
}