SpringBoot+filter+listener+拦截器

Posted 2020-12-24 stt101517

一、过滤器（filter）

　　1.SpringBoot默认加载的过滤器

     　　characterEncodingFilter　　　　　　

　　　  hiddenHttpMethodFilter

　　　  httpPutFormContentFilter

　　　 requestContextFilter

　　2.Filter的优先级

　　　　Ordered.HIGHEST_PRECEDENCE

　　　　Ordered.LOWEST_PRECEDENCE

　　　　地位值意味着更高的优先级，自定义filter避免和默认的filter优先级一样，不然会冲突，注册filter的bean  filterRegistrationBean，同模块里面有默认filter   web---》servlet---》filter

　　3.自定义filter

　　　　使用servlet3.0注解进行配置

　　　　启动类中加载@ServletComponenScan，进行扫描

　　　　新建一个filter类，implements Filter，并实现对应的接口

　　　　@WebFilter标记一个类为filter，被spring进行扫描         urlPatterns  匹配规则

package com.itcast.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 = "/api/*",filterName = "loginFilter")
public class LoginFilter implements Filter {

    /**
     * 容器加載的時候調用
     * @param filterConfig
     * @throws ServletException
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("init loginFilter");
    }

    /**
     * 请求被拦截的时候调用
     * @param request
     * @param response
     * @param filterChain
     * @throws IOException
     * @throws ServletException
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("doFilter loginFilter");
        HttpServletRequest request1 = (HttpServletRequest) request;
        HttpServletResponse response1 = (HttpServletResponse) response;
        String username = request1.getParameter("username");
        if ("123".equals(username)){
            filterChain.doFilter(request,response);
        }else {
            response1.sendRedirect("index.html");
            return;
        }

    }

    /**
     * 容器被销毁的时候调用
     */
    @Override
    public void destroy() {
        System.out.println("destroy loginFilter");
    }
}

package com.itcast;

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

@SpringBootApplication
@ServletComponentScan
public class springBootAdminT {

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

 二、servlet

package com.itcast.servlet;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet(name="userServlet" ,urlPatterns = "/v1/api/test/customs")
public class UserServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("12345");
        resp.getWriter().flush();
        resp.getWriter().close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doPost(req, resp);
    }
}

 三、Listener

　　　　常用的监听器：servletContextListener             httpSessionListtener              servletRequestListener

　　　　

package com.itcast.listener;

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

@WebListener
public class RequestListener implements ServletRequestListener {

    @Override
    public void requestDestroyed(ServletRequestEvent sre) {
        System.out.println("===requestDestroyed===");
    }

    @Override
    public void requestInitialized(ServletRequestEvent sre) {
        System.out.println("=====requestInitialized======");
    }
}

四、Intecpter

package com.itcast.intecpter;

import org.springframework.boot.logging.LoggingInitializationContext;
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 CustomWebMvcConfigurer implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new LoginIntercpter()).addPathPatterns("/api2/*/**");
        WebMvcConfigurer.super.addInterceptors(registry);
    }
}

package com.itcast.intecpter;

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

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

public class LoginIntercpter implements HandlerInterceptor {

    /**
     *进入Controller之前
     * @param request
     * @param response
     * @param handler
     * @return
     * @throws Exception
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("LoginIntercpter---------->>>preHandle");
        return true;
    }

    /**
     * 调用完Controller之后，视图渲染之前
     * @param request
     * @param response
     * @param handler
     * @param modelAndView
     * @throws Exception
     */
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("LoginIntercpter---------->>>postHandle");
    }

    /**
     * 整个完成之后，通常用于资源清理
     * @param request
     * @param response
     * @param handler
     * @param ex
     * @throws Exception
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("LoginIntercpter---------->>>afterCompletion");
    }
}