| (HttpServletRequest) request;
System.out.println(req.getRemoteHost() + " tried to access "
+ req.getRequestURL() + " on " + new Date() + ".");
chain.doFilter(request, response);
System.out.println("Within SimpleFilter1:Filtering the Response...");
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (ServletException se) {
se.printStackTrace();
}
}
public void destroy() {
this.filterConfig = null;
}
}
web.xml设置不变，同章节3。
测试：
输入http://localhost:8080/Test4Jsp/login.jsp
结果：
Within SimpleFilter1:Filtering the Request...
0:0:0:0:0:0:0:1 tried to access http://localhost:8080/Test4Jsp/login.jsp on Sun Mar 04 17:01:37 CST 2007.
Within SimpleFilter2:Filtering the Request...
Within SimpleFilter2:Filtering the Response...
Within SimpleFilter1:Filtering the Response...
Servlet过滤器介绍之原理分析(4)
时间:2011-04-09 51cto zhangjunhd
5．访问时的过滤器（在过滤器中使用servlet初始化参数）
下面利用init设定一个正常访问时间范围，对那些不在此时间段的访问作出记录。我们改 动一下章节3的SimpleFilter2.java。
SimpleFilter2.java。
package com.zj.sample;
import java.io.IOException;
import java.text.DateFormat;
import java.util.Calendar;
import java.util.GregorianCalendar;
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;
import javax.servlet.http.HttpServletRequest;
public class SimpleFilter2 implements Filter {
@SuppressWarnings("unused")
private FilterConfig config;
private ServletContext context;
private int startTime, endTime;
private DateFormat formatter;
public void init(FilterConfig config) throws ServletException {
this.config = config;
context = config.getServletContext();
formatter = DateFormat.getDateTimeInstance(DateFormat.MEDIUM,
DateFormat.MEDIUM);
try {
startTime = Integer.parseInt(config.getInitParameter ("startTime"));// web.xml
endTime = Integer.parseInt(config.getInitParameter("endTime"));// web.xml
} catch (NumberFormatException nfe) { // Malformed or null
// Default: access at or after 10 p.m. but before 6 a.m. is
// considered unusual.
startTime = 22; // 10:00 p.m.
endTime = 6; // 6:00 a.m.
}
}
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) {
try {
System.out.println("Within SimpleFilter2:Filtering the Request...");
HttpServletRequest req = (HttpServletRequest) request;
GregorianCalendar calendar = new GregorianCalendar();
int currentTime = calendar.get(Calendar.HOUR_ |
