EncodingFilter.java

package com.itheima.web.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

//使用注解filter 不要用xml配置文件
@WebFilter(filterName = "EncodingFilter" , urlPatterns = "/*")
public class EncodingFilter implements Filter {
    public void destroy() {
    }

    /**
     * 处理编码
     * @param req
     * @param resp
     * @param chain
     * @throws ServletException
     * @throws IOException
     */
    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {

        try {
            HttpServletRequest request = (HttpServletRequest)req;
            HttpServletResponse response = (HttpServletResponse) resp;

            //在放行之前处理编码
            request.setCharacterEncoding("utf-8");
            response.setHeader("content-type" , "text/html;charset=utf-8");



            //整个代码必须有放行  这个filter只负责编码 没有逻辑
            chain.doFilter(request, response);
        }catch (Exception e){

        }

    }

    public void init(FilterConfig config) throws ServletException {

    }

}