使用过滤器后网站所有页面都不能访问了

[ignited6]

写了一个过滤器aaa.java，禁止直接访问a.jsp，aaa.java在Webcontent文件夹中的WEB-INF文件夹中classes文件夹中user文件夹中yourfilter文件夹里，a.jsp在Webcontent文件夹中，为什么整个网站的所有页面都访问报错了？
web.xml代码如下
<filter>
<filter-name>aaa</filter-name>
<filter-class>user.yourfilter.aaa</filter-class>
</filter>
<filter-mapping>
<filter-name>aaa</filter-name>
<url-pattern>/a.jsp</url-pattern>
</filter-mapping>
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aaa.java代码如下
package user.yourfilter;
import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.FilterChain;
import javax.servlet.ServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
public class Accessforbidden implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
}
public void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException {
PrintWriter out=response.getWriter();
int t=0;
if(t<1){out.print("请不要直接访问这个页面");}
else{ chain.doFilter(request,response);}
}
public void destroy() {}
}