Filter实际应用--字符编码过滤器

骑猪看日落 2022-06-07 05:36 217阅读 0赞

e.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
       <form action="f.jsp" method="post">
           name:<input type="text" name="name">
           <input type="submit" value="submit">
       </form>
    </body>
    </html>

f.jsp:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
       Hello:<%=request.getParameter("name")%>
    </body>
    </html>

在e.jsp输入内容后，在b.jsp显示:

①：输入英文:

![Center][]

②：输入汉字：  
![Center 1][]

可以看到，输入汉字之后，会产生乱码。

这里可以用一个过滤器，将请求的字符编码设置为UTF-8：

package com.sa.filter;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.IOException;
    
    @WebFilter(filterName = "CharacterFilter")
    public class CharacterFilter implements Filter {
        private FilterConfig filterConfig;
        public void destroy() {
        }
    
        public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
            req.setCharacterEncoding(filterConfig.getInitParameter("encoding"));
            chain.doFilter(req, resp);
        }
    
        public void init(FilterConfig config) throws ServletException {
            this.filterConfig=config;
        }
    
    }

web.xml:

<filter>
            <filter-name>CharacterFilter</filter-name>
            <filter-class>com.sa.filter.CharacterFilter</filter-class>
            <init-param>
                <param-name>encoding</param-name>
                <param-value>UTF-8</param-value>
            </init-param>
        </filter>
        <filter-mapping>
            <filter-name>CharacterFilter</filter-name>
            <url-pattern>/*</url-pattern>
    
        </filter-mapping>

再次测试:

![Center 2][]

[Center]: /images/20220607/82b307711b914a5782539fe0686e3264.png
[Center 1]: /images/20220607/c94b76eb333441b39725b9032e62fcd1.png
[Center 2]: /images/20220607/bbff691f1c0a4041aa6f26dd7c346171.png