JavaWeb-24课-filter-2023-04-09

Servlet类，没有乱码处理

package com.feijian.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class helloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().print("你好，美丽的世界！");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}

 写Filter类，需要注意导包为Javax.Servlet

package com.feijian.filter;


import javax.servlet.*;
import java.io.IOException;

public class helloFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
         servletRequest.setCharacterEncoding("utf-8");
         servletResponse.setCharacterEncoding("utf-8");
         filterChain.doFilter(servletRequest,servletResponse);
    }

    @Override
    public void destroy() {

    }
}

web.xml中 注册 servlet 和 filter ，servlet有两个mapping, 一个多了一级目录，servlet， 观察在filter 中的mapping 是什么响应路径

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">

    <servlet>
        <servlet-name>Hello</servlet-name>
        <servlet-class>com.feijian.servlet.helloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Hello</servlet-name>
        <url-pattern>/servlet/hello</url-pattern>
    </servlet-mapping>

    <servlet-mapping>
        <servlet-name>Hello</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>

    <filter>
        <filter-name>filter01</filter-name>
        <filter-class>com.feijian.filter.helloFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>filter01</filter-name>
        <url-pattern>/servlet/*</url-pattern>
    </filter-mapping>
</web-app>