URL重写实现IHttpHandler接口

2024-07-21 02:28:55

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以前用url重写时是用的ms urlrewriter,用了以后发现了很多不足,自定义功能太弱,而且随着重写规则的增加,web.config可能会越来越大,实际上,url重写就是实现ihttphandler接口.

整个流程分二步走:

1、用一个xml文件来存储重写规则,其中这些规则是一些简单的正则表达式
2、实现ihttphandler接口

首先看一下xml文件的格式:

＜?xml version="1.0" encoding="utf-8" ?＞
＜root＞
＜regex＞
＜!--重写以后的虚拟地址--＞
＜b＞＜![cdata[xxx,(?＜id＞[0-9]+).html$]]＞＜/b＞
＜!--实际地址--＞
＜a＞＜![cdata[xxx.aspx?id=${id}]]＞＜/a＞
＜/regex＞
＜/root＞

相信上面的xml大家都能看懂.

using system;
using system.io;
using system.data;
using system.configuration;
using system.collections.generic;
using system.web;
using system.web.security;
using system.web.ui;
using system.web.ui.webcontrols;
using system.web.ui.webcontrols.webparts;
using system.web.ui.htmlcontrols;
using system.text;
using system.text.regularexpressions;
using microsoft.visualbasic;
//regexinfo结构,用来存储从xml文件中读取到的数据
public struct regexinfo
{
    public string _before;
    public string _after;
    public regexinfo(string before, string after)
    {
        _before = before.tolower();
        _after = after.tolower();
    }
}
//ipfilter结构,用来存储被封的ip
public struct ipfilter
{
    public string _ip;
    public ipfilter(string ip)
    {
        _ip = ip;
    }
}
public class htmlhttphandler : ihttphandler   //实现ihttphandler接口
{

    private list＜regexinfo＞ _regex_list = new list＜regexinfo＞();
    private list＜ipfilter＞ _ip_filter = new list＜ipfilter＞();
    public htmlhttphandler()
    {
        dataset ds = new dataset();
        //读取url重写规则文件,并写入regexinfo结构的实例中
        ds.readxml(system.web.httpcontext.current.server.mappath("~/app_data/regexs.xml"));
        foreach (datarow r in ds.tables["regex"].rows)
            _regex_list.add(new regexinfo(((string)r["b"]).trim(), ((string)r["a"]).trim()));
        ds.reset();
        //读取被封的ip列表
        ds.readxml(system.web.httpcontext.current.server.mappath("~/app_data/ipfilter.xml"));
        foreach(datarow r in ds.tables["ipfilters"].rows)
            _ip_filter.add(new ipfilter((string)r["ip"]));
    }

    public void processrequest(httpcontext context)
    {
        string _ip = context.request.userhostaddress;   //获取ip
        foreach (ipfilter r in _ip_filter)
        {
            if (_ip == r._ip)
            {
                context.response.write("对不起,您的ip:"+_ip+"已被限制!");
                context.response.end();
            }
        }
        string path = context.request.path.tolower();   //获取当前访问的重写过的虚假url
        foreach (regexinfo r in _regex_list)
            path = regex.replace(path, r._before, r._after);      //匹配出其真实的url
        context.server.execute(path);
    }

    // override the isreusable property.
    public bool isreusable
    {
        get { return true; }
    }
}