spring-boot-学习笔记（三）-过滤器

  过滤器有两种配置方式，一种是通过注解来完成，一种是通过自定义配置类来设置

这里假设的场景是，定义一个过滤器，过滤所有请求，如果参数中没有username信息则重定向到login_page登录页面，如果带有username则放行

注解-WebFilter

package com.example.demo.myFilter;

import org.springframework.stereotype.Component;

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

/**
 * @author fengxi
 * @date 2019-03-06 10:47
 */


@WebFilter(value = "/*")    // WebFilter注解告诉spring这是一个过滤器
@Component      // Component注解表示这是一个组件，需要创建出一个实例来
public class firstFilter  implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("init，在服务启动的时候被调用");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        String path = req.getRequestURI();
        HttpSession session = req.getSession();
        if (req.getParameter("username") != null){
            // 放行
            chain.doFilter(request, response);
        }else {
            System.out.println(path);
            if (path.equals("/login_page")) {
                // 如果本身访问的是登录页面，直接放行
                chain.doFilter(request, response);
            } else {
                // 没有username，访问非登录页面，重定向到登录页面
                HttpServletResponse resp = (HttpServletResponse) response;
                resp.sendRedirect("login_page");
            }
        }

    }

    @Override
    public void destroy() {
        System.out.println("destroy，在停止服务程序的时候会调用");
    }
}

代码配置

1。 在fitler实现类不使用注解

package com.example.demo.myFilter;

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

/**
 * @author fengxi
 * @date 2019-03-06 15:31
 */
public class secondFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("init");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        String path = req.getRequestURI();
        HttpSession session = req.getSession();
        if (req.getParameter("username") != null){
            chain.doFilter(request, response);
        }else {
            System.out.println(path);
            if (path.equals("/login_page")) {
                chain.doFilter(request, response);
            } else {
                HttpServletResponse resp = (HttpServletResponse) response;
                resp.sendRedirect("login_page");
            }
        }
    }

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

2。 使用configuration注解定义过滤器

package com.example.demo.config;

import com.example.demo.myFilter.secondFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * @author fengxi
 * @date 2019-03-06 15:30
 */

@Configuration
public class myConfig {

    @Bean("bean1")
    public FilterRegistrationBean registerFilter1(){
        // 创建过滤器注册bean对象
        FilterRegistrationBean bean1 = new FilterRegistrationBean();
        // 设置要配置的过滤器对象
        bean1.setFilter(new secondFilter());
        // 添加该过滤器要过滤的url规则
        bean1.addUrlPatterns("/*");
        // 设置过滤器执行的优先级，数字小的先执行
        bean1.setOrder(1);
        return bean1;
    }
}