Spring Boot 之servlet、Filter

小咪咪 2022-05-24 00:06 181阅读 0赞

目的：最近公司的项目中需要用到filter拦截所有请求，看用户是否登录等验证信息，所以把servlet，filter，listener总结一下

一、servlet

1.启动类中添加

@Bean
    	public ServletRegistrationBean getDemoServlet(){
    
    		ServletRegistrationBean registrationBean=new ServletRegistrationBean();
    		registrationBean.setServlet(new DemoServelt());
    		List<String> urlMappings=new ArrayList<String>();
    		urlMappings.add("/demoservlet");访问，可以添加多个
    		registrationBean.setUrlMappings(urlMappings);
    		registrationBean.setLoadOnStartup(1);
    		return registrationBean;
    	}

2.demo类

import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    public class DemoServelt extends HttpServlet{
    
        /**
         *
         */
        private static final long serialVersionUID = 2600143224322327782L;
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            System.out.println("==>DemoServlet接受请求");
            resp.getWriter().write("DemoServlet access success");
    
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            this.doGet(req, resp);
        }
    
    }

二、filter

业务场景：前端每次请求头都必选带token，除了一些不过滤的url，主要用来验证是否有权限去访问微服务。（已经测试）

1.启动类中添加

@Bean
    	public FilterRegistrationBean testFilterRegistration() {
    		FilterRegistrationBean registration = new FilterRegistrationBean(new LoginFilter());
    		List<String> urlPatterns = new ArrayList<String>();
    
    		urlPatterns.add("/*");  //添加过滤的list集合
    
    		registration.setUrlPatterns(urlPatterns);
    		registration.setEnabled(true);  //过滤器的开关
    		return registration;
    	}

2.demo类

import com.exception.AppcationException;
    import com.exception.ExceptionEnum;
    import org.springframework.web.context.support.SpringBeanAutowiringSupport;
    
    import javax.servlet.*;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    import java.util.regex.Matcher;
    import java.util.regex.Pattern;
    
    public class LoginFilter implements Filter {
    
    
        protected static List<Pattern> patterns = new ArrayList<Pattern>();
    
    
    
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(this, filterConfig.getServletContext());
    
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            HttpServletRequest httpRequest = (HttpServletRequest) servletRequest;
            HttpServletResponse httpResponse = (HttpServletResponse) servletResponse;
            String usertoken = httpRequest.getHeader("token");
            String url = httpRequest.getRequestURI().substring(httpRequest.getContextPath().length());
    
    
            String[] regex=new String[10] ;
            regex[0]="^login.*$";
            /** 注意这段   添加不过滤的表达式到list集合
             * swagger的url
             */
            regex[1]="^v2.*$";
            regex[2]="^webjars.*$";
            regex[3]="^swagger.*$";
            for (int i=0;i<=3;i++) {
                patterns.add(Pattern.compile(regex[i]));
            }
            if (url.startsWith("/") && url.length() > 1) {
                url = url.substring(1);
            }
    
            if (isInclude(url)){
                filterChain.doFilter(httpRequest, httpResponse);
                return;
            }else {
    
          if(token==null || token.isEmpty()){
              throw  new AppcationException(ExceptionEnum.NOTFOUNTVALUE);
    
            }else
            {
                System.out.println(token);
            }
    }
        }
    
        @Override
        public void destroy() {
    
        }
        private boolean isInclude(String url) {
            for (Pattern pattern : patterns) {
                Matcher matcher = pattern.matcher(url);
                if (matcher.matches()) {
                    return true;
                }
            }
            return false;
        }
    }