java 过滤器跳转页面_过滤器Filter(拦截jsp页面的跳转)案例：

创建一个 Filter , class类: 其继承于 接口 Filte(接口导包：import javax.servlet.Filter;)

在 web.xml 文件中配置并映射该 Filter. 其中 url-pattern 指定该 Filter 可以拦截哪些资源, 即可以通过哪些 url 访问到该 Filter，并进行拦截；

案例：username=Tom,password=1234,设计Filter类，及jsp页面实现，输入username和password是否等于Tom和1234，不等拦截index.jsp页面跳转到hello.jsp页面，等的或，在在hello，显示；

1.建立UserNameFilter类：继承于接口Filter(接口导包：import javax.servlet.Filter;)

packagecom.lanqiao.javatest;importjava.io.IOException;importjavax.servlet.Filter;importjavax.servlet.FilterChain;importjavax.servlet.FilterConfig;importjavax.servlet.ServletException;importjavax.servlet.ServletRequest;importjavax.servlet.ServletResponse;importorg.apache.catalina.connector.Request;public class UserNameFilter implementsFilter{//构造方法

publicUserNameFilter(){

}public voiddestroy() {

}

@Overridepublic voiddoFilter(ServletRequest request, ServletResponse response, FilterChain chain)throwsIOException, ServletException {

String initUser=filterConfig.getInitParameter("username");

String username=request.getParameter("username");if(!initUser.equals(username)){

request.setAttribute("message", "用户名不正确！！！");

request.getRequestDispatcher("/login.jsp").forward(request, response);return;

}

chain.doFilter(request, response);

}privateFilterConfig filterConfig;

@Overridepublic void init(FilterConfig filterConfig) throwsServletException {this.filterConfig=filterConfig;

}

}

2.建立PasswordFilter类：继承于接口Filter(接口导包：import javax.servlet.Filter;)

packagecom.lanqiao.javatest;importjava.io.IOException;importjavax.servlet.Filter;importjavax.servlet.FilterChain;importjavax.servlet.FilterConfig;importjavax.servlet.ServletException;importjavax.servlet.ServletRequest;importjavax.servlet.ServletResponse;public class PasswordFilter implementsFilter {publicPasswordFilter() {//TODO Auto-generated constructor stub

}

@Overridepublic voiddestroy() {

}

@Overridepublic voiddoFilter(ServletRequest request, ServletResponse response, FilterChain chain)throwsIOException, ServletException {

String initPassword=filterConfig.getServletContext().getInitParameter("password");

String password=request.getParameter("password");if(!initPassword.equals(password)){

request.setAttribute("message", "密码不正确！！！");

request.getRequestDispatcher("/login.jsp").forward(request, response);return;

}

chain.doFilter(request, response);

}privateFilterConfig filterConfig;

@Overridepublic void init(FilterConfig filterConfig) throwsServletException {this.filterConfig=filterConfig;

}

}

3.在WEB-FIN下的web.xml文件下的配置和映射：

day-12

UserNameFilter

com.lanqiao.javatest.UserNameFilter

username

Tom

UserNameFilter

/hello.jsp

password

com.lanqiao.javatest.PasswordFilter

password

/hello.jsp

password

1234

4.index.jsp页面：输入username和password;

Insert title here

${message }

username:
password:

5.hello.jsp页面：

Insert title here