filter类的具体使用和配置

最新推荐文章于 2024-07-25 20:05:55 发布

最新推荐文章于 2024-07-25 20:05:55 发布 · 332 阅读

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本文介绍了如何在web.xml中配置过滤器，并提供了一个具体的Java过滤器类实例，该类用于处理用户登录验证，设置了字符编码并实现了基本的过滤逻辑。

一。web.xml文件配置

xml 代码

二。filter类使用举例

java 代码

package cn.lingqi.filter;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
//用户登陆筛选器
public class LogonFilter implements Filter{
protected FilterConfig filterConfig = null;
protected String encoding = null;
public void destroy() {
// TODO Auto-generated method stub
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
response.setContentType("text/html;charset=gb2312");
PrintWriter out = response.getWriter();
if ((request.getCharacterEncoding() == null)) {
String encoding = selectEncoding(request);
if (encoding != null)
request.setCharacterEncoding(encoding);
}
out.println("<script>alert('test filter');</script>");
chain.doFilter(request, response);
}
public void init(FilterConfig filterConfig) throws ServletException {
this.filterConfig = filterConfig;
this.encoding = filterConfig.getInitParameter("encoding");
}
protected String selectEncoding(ServletRequest request) {
return (this.encoding);
}
}