SpringBoot2.0（过滤器，监听器，拦截器）-Toy模板网

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一，过滤器

1.1，自定义Filter

使用Servlet3.0的注解进行配置

启动类里面增加 @ServletComponentScan ，进行扫描

新建一个Filter类，implements Filter ，并实现对应接口

@WebFilter 标记一个类为Filter，被spring进行扫描

urlPatterns:拦截规则，支持正则

控制chain.doFilter的方法的调用，来实现是否通过放行，
不放行的话，web应用resp.sendRedirect(“/index.html”)
场景：权限控制，用户登录（非前端后端分离场景）等

1.2，启动类代码

package com.demo;

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

@SpringBootApplication
@ServletComponentScan  // 扫描select的注解
public class DemoApplication {


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

}

1.2，创建filter类和LoginFilter包

springboot2 编码过滤器,SpringBoot,spring boot

1.2.1，编写loginFilter类过滤器代码

package com.demo.filter;

import org.springframework.core.Ordered;
import org.springframework.core.annotation.Order;

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


@WebFilter(urlPatterns = {"/*"})
@Order(Ordered.HIGHEST_PRECEDENCE)    // 设置过滤器的排序,int类型
public class LoginFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("初始化过滤器");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("doFilter");
//        servletResponse.setCharacterEncoding("UTF-8");
        // 设置响应的字符编码为UTF-8
        servletResponse.setCharacterEncoding("UTF-8");
        // 设置响应的内容类型为text/plain;charset=UTF-8
        servletResponse.setContentType("text/plain;charset=UTF-8");
        // 登录过滤器 有两种情况，需要放行
        // 1，登录请求要放行
        // 2. 不是登录请求，但是有登录token

        String uri = ((HttpServletRequest)servletRequest).getRequestURI();
        System.out.println(uri);
        if (uri.startsWith("/login/")){  // 判断是否以 /login/ 开头
            // 放行
            filterChain.doFilter(servletRequest,servletResponse);
        }else {
            // 从请求中获取token
            String token = ((HttpServletRequest)servletRequest).getParameter("token");
            if (token != null && !"".equals(token)){
                // 其实还需要进行解码，现在是只要有token就放行
                filterChain.doFilter(servletRequest,servletResponse);
            }else {
                PrintWriter pw = servletResponse.getWriter();
                pw.flush();
                pw.write("请先登录");
                pw.close();
            }
        }


    }

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

1.2.2，创建二个Controller类

看看是不是以login开头的放行

第一个controller类为LoginController

package com.demo.controller;


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


@RestController
@RequestMapping("/login")
public class LoginController {

    @RequestMapping("/doLogin")
    public Object doLogin(){
        return "登录接口";
    }
}

springboot2 编码过滤器,SpringBoot,spring boot

第二个controller类为HelloController

看看不是以login会不会过滤

package com.demo.controller;

import com.demo.bean.Person;
import com.demo.config.BootProperties;
import com.demo.config.SysProperties;
import com.demo.util.ResultUtil;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.env.Environment;
import org.springframework.util.ClassUtils;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.xml.crypto.Data;
import java.io.File;
import java.io.IOException;
import java.util.Date;
import java.util.UUID;


@RestController
public class HelloController {

    @Autowired
    private BootProperties bootProperties;

    @RequestMapping("/test6")
    public Object test6(){
        return sysProperties.getParam1()+sysProperties.getParam2();
    }
}
// 整个之前的代码试试

springboot2 编码过滤器,SpringBoot,spring boot
证明过滤了，试试登录后

springboot2 编码过滤器,SpringBoot,spring boot

二，监听器

2.1，自定义监听器

自定义Listenter（常用监听器
servletContextListenter，
httpSessionListenter，
HTTPSessionAttributeListenter，
servletRequestListenter）

2.2，创建listenter包和MyListenter类

springboot2 编码过滤器,SpringBoot,spring boot

2.2.1，编写MyListenter类监听器代码

package com.demo.listener;

import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.annotation.WebListener;


@WebListener
public class MyListener implements ServletRequestListener {
    @Override
    public void requestDestroyed(ServletRequestEvent servletRequestEvent) {
        System.out.println("请求被销毁");
    }

    @Override
    public void requestInitialized(ServletRequestEvent servletRequestEvent) {
        System.out.println("请求被初始化创建");
    }
}

三，拦截器

3.1，创建自定义拦截器配置类

@Configuration
继承WebMvcConfigurationAdapter（SpringBoot2.X之前旧版本）
SpringBoot2.X新版本配置拦截器 implements WebMvcConfigurer

3.2，创建配置包config和配置类MyWebMvcConfigurer

springboot2 编码过滤器,SpringBoot,spring boot

package com.demo.config;

import com.demo.interceptor.Logininterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration  // 添加了Configuration的类，我们称之为配置类
public class MyWebMvcConfigurer implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new Logininterceptor()).addPathPatterns("/login/**");
        WebMvcConfigurer.super.addInterceptors(registry);
    }
}

3.3，创建拦截器包interceptor和Logininterceptor类

springboot2 编码过滤器,SpringBoot,spring boot

Logininterceptor类代码

package com.demo.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 Logininterceptor implements HandlerInterceptor {
    // 调用Controller某个方法之前，判断是否要不要处理
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false; // false是拦截, true是不拦截
    }

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

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("afterCompletion");
    }
}