过滤器的使用

原理

当未加过滤器时，页面显示乱码

加了过滤器

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" version="4.0">
  <display-name>myTest1</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>MyServlet1</servlet-name>
    <servlet-class>cn.swpu.pang.MyServlet1</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>MyServlet1</servlet-name>
    <url-pattern>/login</url-pattern>
  </servlet-mapping>
  
  <filter>
     <filter-name>MyFilter1</filter-name>
     <filter-class>cn.swpu.pang.MyFilter1</filter-class>
   </filter>
   
   <filter-mapping>
        <filter-name>MyFilter1</filter-name>
        <url-pattern>/*</url-pattern>
   </filter-mapping>
  
</web-app>

package cn.swpu.pang;

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;
import javax.servlet.annotation.WebFilter;

/**
 * Servlet Filter implementation class MyFilter1
 */
@WebFilter("/MyFilter1")
public class MyFilter1 implements Filter {

    /**
     * Default constructor. 
     */
    public MyFilter1() {
        // 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 {
        System.out.println("我的filter");
        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        chain.doFilter(request, response);
    }

    /**
     * @see Filter#init(FilterConfig)
     */
    public void init(FilterConfig fConfig) throws ServletException {
        // TODO Auto-generated method stub
    }

}