JavaWeb中Filter(过滤器)

最新推荐文章于 2022-06-21 16:33:16 发布

原创最新推荐文章于 2022-06-21 16:33:16 发布 · 146 阅读

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文章标签：

#java #spring #java-ee

本文介绍了如何在Java中实现一个Servlet Filter，用于设置请求和响应的字符编码，并展示了在web.xml中的配置方法。示例代码展示了/servlet/*路径下的请求会经过filter，而/s1则不会。

1、导包，filter代码
在这里插入图片描述

import javax.servlet.*;
import java.io.IOException;

public class filter implements Filter {
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            servletResponse.setCharacterEncoding("UTF-8");          //通过过滤器设置响应得字符格式
            servletRequest.setCharacterEncoding("UTF-8");           
            servletResponse.setContentType("text/html;Charset=utf-8");

            System.out.println("filter执行之前");
            filterChain.doFilter(servletRequest,servletResponse);
            System.out.println("filter执行之后");
    }

    public void destroy() {
        
    }
}

2、在web.xml中配置filter

   <filter>
        <filter-name>filter_1</filter-name>
        <filter-class>com.cling.filter.filter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>filter_1</filter-name>
       <url-pattern>/servlet/*</url-pattern>
    </filter-mapping>

下面得代码中/s1没有经过filter，而/servlet/s1经过了filter。

    <servlet-mapping>
        <servlet-name>s1</servlet-name>
        <url-pattern>/s1</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>s1</servlet-name>
        <url-pattern>/servlet/s1</url-pattern>
    </servlet-mapping>