潍坊网站建设科技有限公司/邯郸seo

1.MVC三层架构

mould 模型，view 视图，controller控制器

2.Filter过滤器

Filter：过滤器、用于过滤网站的数据

1.处理中文乱码

2.登录验证。。。。

举个例子：

我们没有使用过滤器，就需要在里面写入解决乱码的问题！

package com.xcl.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 ServletDemo01 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {resp.setContentType("text/html;charset=utf-8");resp.getWriter().write("你好，张三！");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}
}

下面是我们中间加上filter的结果：

package com.xcl.Filter;import javax.servlet.*;
import java.io.IOException;public class FilterDemo01 implements Filter {// 初始化方法public void init(FilterConfig filterConfig) throws ServletException {}public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {servletResponse.setContentType("text/html;charset=utf-8");servletResponse.setCharacterEncoding("utf-8");System.out.println("FilterDemo01过滤器开始工作...");filterChain.doFilter(servletRequest, servletResponse);//让我们请求继续走，如果请求不写，程序就会卡在这里！System.out.println("FilterDemo01过滤器工作结束...");}// 销毁方法public void destroy() {System.out.println("FilterDemo01过滤器销毁...");}
}

package com.xcl.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 ServletDemo01 extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {resp.getWriter().write("你好，张三！");}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {doGet(req, resp);}
}