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("初始化攔截器");
    }
 
    @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("攔截器銷(xiāo)毀");
    }
}

?????2 創(chuàng)建測(cè)試類(lèi)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("登錄");
        return "login";
    }
 
}

? ? ? 3 在啟動(dòng)類(lèi)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可以直接通過(guò)@WebServlet、@WebFilter、@WebListener注解自動(dòng)注冊(cè)
public class DemoApplication {
 
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
 
}

? 4 啟動(dòng)測(cè)試，啟動(dòng)的時(shí)候可以看到Filter調(diào)用init方法初始化

?接著訪(fǎng)問(wèn)可以看到頁(yè)面輸出

?控制臺(tái)打印出攔截器中的語(yǔ)句

2、攔截器 ? ? ? ?

1 創(chuàng)建自定義攔截器

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 {
   //進(jìn)入controller方法之前調(diào)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
    }
    //調(diào)用完controller之后，視圖渲染層之前
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("postHandle");
    }
    //頁(yè)面跳轉(zhuǎn)之后，整個(gè)流程執(zhí)行之后，一般用于資源的清理
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }
}

? ? ? 2 創(chuàng)建攔截器配置類(lèi)，注意要加上配置類(lèi)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) {
        //設(shè)置攔截器并指定攔截路徑
        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/interceptor/*");
        //registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");//攔截所有
        //registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**").excludePathPatterns("/test");//指定不攔截
 
        //添加自定義攔截器
        WebMvcConfigurer.super.addInterceptors(registry);
    }
}

? ? ? ? 3 創(chuàng)建LoginController測(cè)試類(lèi)

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 運(yùn)行訪(fǎng)問(wèn)，查看效果