查验用户名、密码、字符编码、页面缓存-Filter的基本使用
检验用户名、密码、字符编码、页面缓存----Filter的基本使用
login.jsp
hello.jsp
EncodingFilter.java
NoCacheFilter.java
NameFilter.java
PasswordFilter.java
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <font color="red">${requestScope.errormsg }</font> <br><br> <form action="hello.jsp" method="post"> Name: <input type="text" name="name"/><br><br> Password: <input type="password" name="password"/><br><br> <input type="submit" value="Submit"/> </form> </body> </html>
hello.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <h4>Hello Page</h4><br><br> <% //request.setCharacterEncoding("UTF-8") ; %> hello : ${param.name }<br><br> </body> </html>
EncodingFilter.java
package com.syh.filter; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; /** * 字符编码过滤器,在设置这个过滤器的时候,还要将Tomcat的一个配置改变: * 修改 Tomcat 服务器的 conf 目录下的 server.xml 文件中的 <Connector> 为(67 行) <Connector port="8989" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" useBodyEncodingForURI="true" />,再次重新启动Tomcat服务器 * @author Administrator * */ public class EncodingFilter implements Filter { private FilterConfig config ; @Override public void init(FilterConfig filterConfig) throws ServletException { this.config = filterConfig ; } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { //1. 获取 ServletContext 对象 ServletContext servletContext = config.getServletContext() ; //2. 获取 encoding 的初始化参数 String encoding = servletContext.getInitParameter("encoding") ; //3. 设置 request 的字符编码 request.setCharacterEncoding(encoding) ; chain.doFilter(request, response) ; } @Override public void destroy() { } }
NoCacheFilter.java
package com.syh.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; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 使浏览器不缓存页面的过滤器 * @author Administrator * */ public class NoCacheFilter implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { } @Override public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws IOException, ServletException { HttpServletResponse response = (HttpServletResponse) resp ; // 并不是所有的浏览器都能完全支持上面的三个响应头, 因此最好是同时使用下面的三个响应头 response.setDateHeader("Expires",-1); response.setHeader("Cache-Control","no-cache"); response.setHeader("Pragma","no-cache"); chain.doFilter(req, resp) ; } @Override public void destroy() { } }
NameFilter.java
package com.syh.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; /** * 用户名检验过滤器 * @author Administrator * */ public class NameFilter implements Filter { private FilterConfig config ; @Override public void init(FilterConfig filterConfig) throws ServletException { this.config = filterConfig ; } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { //1. 获取表单中 name 的参数 String paramName = request.getParameter("name") ; //2. 获取当前 Filter 中 name 的参数 String initName = config.getInitParameter("name") ; //3. 比较 if(paramName != null && initName.equals(paramName)) { //3.1 匹配,放行 chain.doFilter(request, response) ; }else { //3.2 不匹配, 将页面转发到 /login.jsp, 并提示用户 "您输入的用户名不同" request.setAttribute("errormsg", "您输入的用户名" + paramName + "不同") ; request.getRequestDispatcher("/login.jsp").forward(request,response) ; } } @Override public void destroy() { } }
PasswordFilter.java
package com.syh.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; /** * 密码检验过滤器 * @author Administrator * */ public class PasswordFilter implements Filter { private FilterConfig config ; @Override public void init(FilterConfig filterConfig) throws ServletException { this.config = filterConfig ; } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { //1.获取表单中 password 的参数 String paramPassword = request.getParameter("password") ; //2. 获取当前 Filter 的 password 的参数 String initPassword = config.getInitParameter("password") ; //3. 比较 if(paramPassword != null && initPassword.equals(paramPassword)) { //3.1 匹配, 放行 chain.doFilter(request, response) ; } else { //3.2 不匹配, 将页面转发到 /login.jsp, 并提示用户 "您输入的密码不正确" request.setAttribute("errormsg", "您输入的密码不正确") ; request.getRequestDispatcher("/login.jsp").forward(request, response) ; } } @Override public void destroy() { } }
<!-- 字符编码的参数 --> <context-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </context-param> <!-- 字符编码的检验 --> <filter> <filter-name>EncodingFilter</filter-name> <filter-class>com.syh.filter.EncodingFilter</filter-class> </filter> <filter-mapping> <filter-name>EncodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- 浏览器缓存的检验 --> <filter> <filter-name>NoCacheFilter</filter-name> <filter-class>com.syh.filter.NoCacheFilter</filter-class> </filter> <filter-mapping> <filter-name>NoCacheFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <!-- 用户名的检验 --> <filter> <filter-name>NameFilter</filter-name> <filter-class>com.syh.filter.NameFilter</filter-class> <init-param> <param-name>name</param-name> <param-value>Tom</param-value> </init-param> </filter> <filter-mapping> <filter-name>NameFilter</filter-name> <url-pattern>/hello.jsp</url-pattern> </filter-mapping> <!-- 用户名的检验 --> <filter> <filter-name>PasswordFilter</filter-name> <filter-class>com.syh.filter.PasswordFilter</filter-class> <init-param> <param-name>password</param-name> <param-value>1234</param-value> </init-param> </filter> <filter-mapping> <filter-name>PasswordFilter</filter-name> <url-pattern>/hello.jsp</url-pattern> </filter-mapping>