2_过滤器的定义和配置

不念不忘少年蓝@ 2023-09-27 15:34 13阅读 0赞

采用三步走策略使用filter

1开发后台资源 静态资源(html,css … …)或者动态资源(Servlet,Jsp)

2开发Filter

3在web.xml中配置Filter拦截哪些资源

开发Servlet

定义两个servlet

package com.msb.servlet;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    /**
     * @Author: Ma HaiYang
     * @Description: MircoMessage:Mark_7001
     */
    public class MyServlet1 extends HttpServlet {
        @Override
        protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("myServlet1 执行了sevice方法");
            resp.setContentType("text/html;charset=UTF-8");
            resp.setCharacterEncoding("UTF-8");
            resp.getWriter().print("myServlet1响应的数据");
        }
    }

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![88c996b72474035f81383e6897b9335c.gif][]

package com.msb.servlet;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    /**
     * @Author: Ma HaiYang
     * @Description: MircoMessage:Mark_7001
     */
    public class MyServlet2 extends HttpServlet {
        @Override
        protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("myServlet2 执行了sevice方法");
            resp.setContentType("text/html;charset=UTF-8");
            resp.setCharacterEncoding("UTF-8");
            resp.getWriter().print("myServlet2响应的数据");
        }
    }

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![6d6e68f612e57dd33b876b11e863993f.gif][]

开发Filter

package com.msb.filter;
    import javax.servlet.*;
    import java.io.IOException;
    /**
     * @Author: Ma HaiYang
     * @Description: MircoMessage:Mark_7001
     */
    public class MyFilter implements Filter {
        // 初始化方法
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
        }
        // 作出过滤的方法
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            System.out.println("Filter doFilter 对请求作出过滤");
            // 通过一行代码 放行请求
            // 放行请求,交给过滤器链继续进行过滤 最后到达资源
            filterChain.doFilter(servletRequest, servletResponse);
            
            System.out.println("Filter doFilter 对响应作出过滤");
            
            servletResponse.getWriter().print("filter 追加一些数据");
        }
        // 销毁方法
        @Override
        public void destroy() {
        }
    }

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![9ba2bab160602641b6bffa6c573ad1de.gif][]

配置Filter

<?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
             version="4.0">
        <servlet>
            <servlet-name>myServlet1</servlet-name>
            <servlet-class>com.msb.servlet.MyServlet1</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>myServlet1</servlet-name>
            <url-pattern>/myServlet1.do</url-pattern>
        </servlet-mapping>
        <servlet>
            <servlet-name>myServlet2</servlet-name>
            <servlet-class>com.msb.servlet.MyServlet2</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>myServlet2</servlet-name>
            <url-pattern>/myServlet2.do</url-pattern>
        </servlet-mapping>
        <filter>
            <filter-name>filter1</filter-name>
            <filter-class>com.msb.filter.MyFilter</filter-class>
        </filter>
        <filter-mapping>
            <filter-name>filter1</filter-name>
            
            
            <servlet-name>myServlet1</servlet-name>
            <servlet-name>myServlet2</servlet-name>
            
        </filter-mapping>
    </web-app>

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[88c996b72474035f81383e6897b9335c.gif]: https://img-blog.csdnimg.cn/img_convert/88c996b72474035f81383e6897b9335c.gif
[2546b1e724877a8f3cd37e6cad5eeb0b.gif]: https://img-blog.csdnimg.cn/img_convert/2546b1e724877a8f3cd37e6cad5eeb0b.gif
[6d6e68f612e57dd33b876b11e863993f.gif]: https://img-blog.csdnimg.cn/img_convert/6d6e68f612e57dd33b876b11e863993f.gif
[a0bcf3414239edea245975cf95c39f55.gif]: https://img-blog.csdnimg.cn/img_convert/a0bcf3414239edea245975cf95c39f55.gif
[9ba2bab160602641b6bffa6c573ad1de.gif]: https://img-blog.csdnimg.cn/img_convert/9ba2bab160602641b6bffa6c573ad1de.gif
[8b4bfac9726b5f7a77fe0252649e90f5.gif]: https://img-blog.csdnimg.cn/img_convert/8b4bfac9726b5f7a77fe0252649e90f5.gif
[aaede47bb61b8fd0aab23034d6a1b1f7.gif]: https://img-blog.csdnimg.cn/img_convert/aaede47bb61b8fd0aab23034d6a1b1f7.gif