Filter sample

最新推荐文章于 2023-07-13 19:48:17 发布

转载最新推荐文章于 2023-07-13 19:48:17 发布 · 635 阅读

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本文介绍了一种基于Java的Web应用中实现的登录验证过滤器和统一字符编码过滤器。登录过滤器通过检查session中是否存在登录标识来决定是否允许访问受保护资源，而字符编码过滤器则确保所有请求都使用UTF-8编码。

source:http://blog.sina.com.cn/u/4cbe337a01000adu

LoginFilter.java:

import javax.servlet.FilterChain;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.FilterConfig;

/**//*
*
* @author Ace
* web.xml配置如下：
* <filter>
* <filter-name>login</filter-name>
* <filter-class>
* org.waityou.news.util.filters.LoginFilter
* </filter-class>
* </filter>
* <filter-mapping>
* <filter-name>login</filter-name>
* <url-pattern>/manager/*</url-pattern>
* </filter-mapping>
*/
public class LoginFilter implements Filter {

    protected FilterConfig filterConfig;

    public void doFilter(final ServletRequest req, final ServletResponse res,
            FilterChain chain) throws IOException, ServletException {
        HttpServletRequest hreq = (HttpServletRequest) req;
        HttpServletResponse hres = (HttpServletResponse) res;
        String isLog = (String) hreq.getSession().getAttribute("isLog");
        if ((isLog != null) && ((isLog.equals("true")) || (isLog == "true")))//检查是否登录
        {
            chain.doFilter(req, res);
            return;
        } else
            hres.sendRedirect("/error.html");//如果没有登录，把视图派发到登录页面
    }

    public void destroy() {
        this.filterConfig = null;
    }

    public void init(FilterConfig config) {
        this.filterConfig = config;
    }

    public void setFilterConfig(final FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }
}

SetCharacterEncodingFilter.java:

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

/** *//**
* @author Ace 编码过滤，一律设置成UTF-8
*
* web.xml中配置如下：
* <filter>
* <filter-name>Set Character Encoding</filter-name>
* <filter-class>
* org.waityou.news.util.filters.SetCharacterEncodingFilter
* </filter-class>
* </filter>
* <filter-mapping>
* <filter-name>Set Character Encoding</filter-name>
* <url-pattern>/*</url-pattern>
* </filter-mapping>
*/
public class SetCharacterEncodingFilter implements Filter {

    public void destroy() {}
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        request.setCharacterEncoding("UTF-8");
        // 传递控制到下一个过滤器
        chain.doFilter(request, response);
    }

    public void init(FilterConfig filterConfig) throws ServletException {}

}