Servlet篩檢程式示例

在本節中，給出了一個有用的篩檢程式示例。

這是一個僅通過篩檢程式發送回應的示例 -

檔：MyFilter.java

import java.io.*;
import javax.servlet.*;

public class MyFilter implements Filter{
    public void init(FilterConfig arg0) throws ServletException {}

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {

        PrintWriter out=res.getWriter();

        out.print("<br/>this site is underconstruction..");
        out.close();

    }
    public void destroy() {}
}

計算單頁訪問次數的示例

檔：MyFilter.java

import java.io.*;
import javax.servlet.*;

public class MyFilter implements Filter{
    static int count=0;
    public void init(FilterConfig arg0) throws ServletException {}

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {

        PrintWriter out=res.getWriter();
        chain.doFilter(request,response);

        out.print("<br/>Total visitors "+(++count));
        out.close();

    }
    public void destroy() {}
}

在篩檢程式中檢查總回應時間的示例

檔：MyFilter.java

import java.io.*;
import javax.servlet.*;

public class MyFilter implements Filter{
    static int count=0;
    public void init(FilterConfig arg0) throws ServletException {}

    public void doFilter(ServletRequest req, ServletResponse res,
            FilterChain chain) throws IOException, ServletException {

        PrintWriter out=res.getWriter();
        long before=System.currentTimeMillis();

        chain.doFilter(request,response);

        long after=System.currentTimeMillis();
        out.print("<br/>Total response time "+(after-before)+" miliseconds");
        out.close();

    }
    public void destroy() {}
}