1.创建两个Filter过滤器UserNameFilter/PassWordFilter
2.进行Filter的注册和配置
3.Filter初始化参数和web应用的初始化参数
4.在Filter中完成信息比较
实现效果：
实现代码：
UserNameFilter
package com.demo.filter;
import javax.servlet.*;
import java.io.IOException;
public class UserNameFilter implements Filter {
private FilterConfig filterConfig;
@Override
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
String initUser = filterConfig.getInitParameter("username");
String username = servletRequest.getParameter("username");
if (!initUser.equals(username)){
servletRequest.setAttribute("message","用户名不正确");
servletRequest.getRequestDispatcher("login.jsp").forward(servletRequest,servletResponse);
return;
}
filterChain.doFilter(servletRequest,servletResponse);
}
@Override
public void destroy() {
}
}
PassWordFilter
package com.demo.filter;
import javax.servlet.*;
import java.io.IOException;
public class PassWordFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
}
private FilterConfig filterConfig;
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
String initPassword = filterConfig.getServletContext().getInitParameter("password");
String password = servletRequest.getParameter("password");
if (!initPassword.equals(password)){
servletRequest.setAttribute("message","密码不正确");
servletRequest.getRequestDispatcher("login.jsp").forward(servletRequest,servletResponse);
return;
}
filterChain.doFilter(servletRequest,servletResponse);
}
@Override
public void destroy() {
}
}
web.xml
<filter>
<filter-name>UserNameFilter</filter-name>
<filter-class>com.demo.filter.UserNameFilter</filter-class>
<init-param>
<param-name>username</param-name>
<param-value>Tom</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>UserNameFilter</filter-name>
<url-pattern>/filter/hello.jsp</url-pattern>
</filter-mapping>
<filter>
<filter-name>PassWordFilter</filter-name>
<filter-class>com.demo.filter.PassWordFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>PassWordFilter</filter-name>
<url-pattern>/filter/hello.jsp</url-pattern>
</filter-mapping>
<context-param>
<param-name>password</param-name>
<param-value>1234</param-value>
</context-param>
login.jsp
<%--
Created by IntelliJ IDEA.
User: dell
Date: 2019/7/16
Time: 14:54
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<font color="red">
${message}
</font>
<br><br>
<form action="hello.jsp" method="post">
username: <input type="text" name="username" value="${param.username}">
password: <input type="password" name="password">
<input type="submit" value="Submit">
</form>
</body>
</html>
hello.jsp
<%--
Created by IntelliJ IDEA.
User: dell
Date: 2019/7/16
Time: 14:57
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
Hello:${param.username}
</body>
</html>