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

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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 */ (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 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

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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

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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; } }