【servlet】 过滤器模板

EncodingFilter.java

package 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;

public class EncodingFilter implements Filter {
    private String encode;

    public void destroy(){
        this.encode = null;
    }

    public void doFilter(ServletRequest req,ServletResponse resp,FilterChain chain)
    throws ServletException,IOException{
        if(encode != null){
            req.setCharacterEncoding(encode);
            resp.setCharacterEncoding(encode);
        }
        chain.doFilter(req,resp);
    }

    public void init(FilterConfig config)throws ServletException{
        encode = config.getInitParameter("encode");
        System.out.println("CharacterEncoding=" + encode );

    }

}

web.xml 配置（WebRoot下的 WEB-INF下的 web.xml）

servlet的配置可忽略（仅保持完整性），主要看Filter的配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">

  <filter>
      <filter-name>encode</filter-name>
      <filter-class>Filter.EncodingFilter</filter-class>
      <init-param>
          <param-name>encode</param-name>
          <param-value>utf-8</param-value>
      </init-param>
  </filter>

  <filter-mapping>
      <filter-name>encode</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>

  <servlet>
    <servlet-name>helloyt</servlet-name>
    <servlet-class>day01.Helloyt</servlet-class>
  </servlet>

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

</web-app>