javaweb过滤器Filter

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我是大头鸟 2022-07-07 17:31:54 博主文章分类：java ©著作权

文章标签 java Filter xml 客户端 文章分类 Java 后端开发

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如何配置过滤器，为什么要配置过滤器，接下来我们来看:

为什么要配置过滤器:针对来自客户端的请求，我们可以我们需要最为简单，最为迫切的是编码的过滤

<filter>
    <description>字符集过滤器</description>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
    <init-param>
      <param-name>forceEncoding</param-name>
      <param-value>true</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

,上面编码的过滤可以告诉我们为什么要过滤，那么如何配置自己的过滤器:web.xml中如此配置:

<filter>
    <filter-name>sessionFilter</filter-name>
    <filter-class>com.wdg.filter.SessionFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>sessionFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  <filter>
    <display-name>SessionFilter</display-name>
    <filter-name>SessionFilter</filter-name>
    <filter-class>com.wdg.filter.SessionFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>SessionFilter</filter-name>
    <url-pattern>/SessionFilter</url-pattern>
  </filter-mapping>

上面是配置了一个SessionFilter，这样的一个过滤，那么我们要创建这样的过滤器，

javaweb过滤器Filter_客户端

代码如下:

package com.wdg.filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/**
 * Servlet Filter implementation class SessionFilter
 */
public class SessionFilter implements Filter
{

    /**
     * Default constructor. 
     */
    public SessionFilter() {
        // TODO Auto-generated constructor stub
    }

    /**
     * @see Filter#destroy()
     */
    public void destroy() {
        // TODO Auto-generated method stub
    }

    /**
     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
     */
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
            throws IOException, ServletException {
        // TODO Auto-generated method stub
        // place your code here
        System.out.println("333");
        // pass the request along the filter chain
        chain.doFilter(request, response);
    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        // TODO Auto-generated method stub
        System.out.println("111");
    }

}