Servlet过滤器处理中文乱码问题

以你之姓@ 2021-07-25 01:35 480阅读 0赞

**目录**

一 Filter开发步骤

二 实战

三 测试结果

--------------------

# **一 Filter开发步骤** #

1 导包

2 编写过滤器

# **二 实战** #

1 编写Servlet，用于测试

package com.cakin.servlet;
    
    
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    
    
    /**
    * @ClassName: ShowSevlet
    * @Description: 测试乱码Servlet
    * @Date: 2020/6/14
    * @Author: cakin
    */
    public class ShowServlet extends HttpServlet {
        /**
         * 功能描述：构造乱码
         *
         * @author cakin
         * @date 2020/6/14
         * @param req 请求
         * @param resp 响应
         * @throws IOException 异常
         */
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
            resp.getWriter().write("解决过滤器乱码问题");
        }
    
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
            doGet(req, resp);
        }
    }

2 编写过滤器，防止产生中文乱码

package com.cakin.filter;
    
    
    import javax.servlet.Filter;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import javax.servlet.FilterChain;
    import java.io.IOException;
    
    
    /**
    * @ClassName: CharacterEncodingFilter
    * @Description: 解决中文乱码问题
    * @Date: 2020/6/14
    * @Author: cakin
    */
    public class CharacterEncodingFilter implements Filter {
        /**
         * 功能描述：初始化
         *
         * @author cakin
         * @date 2020/6/14
         * @param filterConfig 过滤器配置
         * @throws ServletException ServletException
         * @description: web启动就会初始化，同Tomcat一起启动
         */
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("CharacterEncodingFilter 初始化");
        }
    
    
        /**
         * 功能描述：过滤器核心方法
         *
         * @param request  请求
         * @param response 响应
         * @param chain    过滤器链
         * @throws IOException      IOException
         * @throws ServletException IOException
         * @author cakin
         * @date 2020/6/14
         * @description: 关键点
         * 1 针对特定的请求，过滤器会执行，这个特定的请求是在web.xml中配置过滤器
         * 2 为了让程序继续往下走，必须执行 chain.doFilter(request, response);
         */
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
            // 处理乱码问题
            request.setCharacterEncoding("utf-8");
            response.setCharacterEncoding("utf-8");
            response.setContentType("text/html;charset=UTF-8");
            System.out.println("执行前");
            // 让我们的程序继续往下走，否则程序就在这里停止了
            chain.doFilter(request, response);
            System.out.println("执行后");
        }
        /**
         * 功能描述：过滤器销毁
         *
         * @author cakin
         * @date 2020/6/14
         * @description: web服务器停止时，会执行这个函数
         */
        public void destroy() {
            System.out.println("CharacterEncodingFilter 销毁");
        }
    }

3 编写web.xml，配置Servlet和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>ShowServlet</servlet-name>
            <servlet-class>com.cakin.servlet.ShowServlet</servlet-class>
        </servlet>
        <servlet-mapping>
            <servlet-name>ShowServlet</servlet-name>
            
            <url-pattern>/servlet/show</url-pattern>
        </servlet-mapping>
        <servlet-mapping>
            <servlet-name>ShowServlet</servlet-name>
            <url-pattern>/show</url-pattern>
            
        </servlet-mapping>
        
        <filter>
            <filter-name>EncodingFilter</filter-name>
            <filter-class>com.cakin.filter.CharacterEncodingFilter</filter-class>
        </filter>
    
    
        <filter-mapping>
            <filter-name>EncodingFilter</filter-name>
            
            <url-pattern>/servlet/*</url-pattern>
        </filter-mapping>
    </web-app>

# **三 测试结果** #

1 当访问 [http://localhost:8080/servlet/show][http_localhost_8080_servlet_show]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70][]

2 当访问 [http://localhost:8080/show][http_localhost_8080_servlet_show]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1][]

[http_localhost_8080_servlet_show]: http://localhost:8080/servlet/show
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70]: /images/20210724/1fdf9be8b7564604bd685b2d6c263465.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NoZW5ncWl1bWluZw_size_16_color_FFFFFF_t_70 1]: /images/20210724/1995c826e63b443798ac805c77596b46.png