构建过滤器filter

1.创建包，新建Filter类，



package com.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 filter implements Filter{

public void destroy() {
// TODO Auto-generated method stub

}

public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {
   request.setCharacterEncoding("utf-8");
   response.setCharacterEncoding("utf-8");
   chain.doFilter(request, response);
// TODO Auto-generated method stub

}

public void init(FilterConfig filterConfig) throws ServletException {
// TODO Auto-generated method stub

}


}
2.在web.xml中添加

  <filter>
  <filter-name>123</filter-name>
  <filter-class>com.filter.filter</filter-class>
 
  </filter>
  <filter-mapping>
 
  <filter-name>123</filter-name>
  <url-pattern>/*</url-pattern>
 
  </filter-mapping>