servler filter 学习记录
String str = request.getParameter("message");//参数System.out.println(str);request.setAttribute("username", "over");//属性//跳转方法1，浏览器地址栏变成了目标页面的url//到了目标页面之后,request内的参数值，属性值丢失了//response.sendRedirect("/PrjFu8/result.jsp");//跳转方法2，浏览器地址栏没有变成目标页面的url//相当于在服务器内部将目标页面的输出送给客户端,request内的参数值，属性值没有丢失//ServletContext application = this.getServletContext();//RequestDispatcher rd = application.getRequestDispatcher("/result.jsp");//rd.forward(request, response);//<jsp:forward>标签/* * 如果在A页面有一些内容要在B页面显示，但是如果内容数量较大，并且是暂态数据 * 可以将内容不要放在session内，放在request内，用跳转方法2跳转到B页面显示，节省内存 * 跳转方法1相当于重新在客户端输入目标页面地址，重新请求 * 方法2相当于服务器内部的跳转 * 如果要跳转到服务器以外的url,必须使用方法1 * *///表示将目标页面的代码插入到这里运行response.setCharacterEncoding("gb2312");ServletContext application = this.getServletContext();RequestDispatcher rd = application.getRequestDispatcher("/result.jsp");rd.include(request, response);//读取全局参数ServletContext application = this.getServletContext();String value1 = application.getInitParameter("GlobalParam");System.out.println(value1);//读取局部参数String value2 = this.getInitParameter("LocalParam");System.out.println(value2);package 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 EncodingFilter implements Filter {public EncodingFilter(){System.out.println("过滤器构造函数");}private String encodingName;public void init(FilterConfig fc) throws ServletException {//初始化函数，服务器运行能自动运行一次System.out.println("过滤器init函数");//fc.getServletContext().getInitParameter(arg0)得到全局参数encodingName = fc.getInitParameter("encodingName");//得到局部参数}public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {//每次提交都会运行System.out.println("过滤器doFilter函数");request.setCharacterEncoding(encodingName);//解决中文问题//过滤器是在提交到达处理模块之前运行，所以这里要将请求向后传递chain.doFilter(request, response);}public void destroy() {//消亡时运行System.out.println("过滤器destroy函数");}}<!-- 注册过滤器 --> - <filter> <filter-name>EncodingFilter</filter-name> <filter-class>filter.EncodingFilter</filter-class> - <init-param> <param-name>encodingName</param-name> <param-value>gb2312</param-value> </init-param> </filter>- <!-- 配置过滤器要过滤的对象 --> - <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>/*</url-pattern> - <!-- 可以写一个url路径 --> </filter-mapping>