asp.net 使用Response.Filter 过滤非法词汇

另一种解决方案是在输出时过滤掉非常词汇，优点是只要写一次就好了，可以过滤整站的非法词汇，缺点是，非法词汇仍然存入到了数据库中，呵呵，大家可以有针对性的选择，本例用的是后者，起因在于当初没有做此功能，后来需要添加，这时又不想改原来代码，所以就想了这个办法，主要是采用了httpresponse.filter属性来处理。具体代码如下：

首先自定义一个类，来作为非法词汇的过滤器

public class responsefilter:stream
{
#region properties
stream responsestream;
long position;
stringbuilder html = new stringbuilder();
#endregion
#region constructor
public responsefilter(stream inputstream)
{
responsestream = inputstream;
}
#endregion
#region implemented abstract members
public override bool canread
{
get { return true; }
}
public override bool canseek
{
get { return true; }
}
public override bool canwrite
{
get { return true; }
}
public override void close()
{
responsestream.close();
}
public override void flush()
{
responsestream.flush();
}
public override long length
{
get { return 0; }
}
public override long position
{
get { return position; }
set { position = value; }
}
public override long seek(long offset, system.io.seekorigin direction)
{
return responsestream.seek(offset, direction);
}
public override void setlength(long length)
{
responsestream.setlength(length);
}
public override int read(byte[] buffer, int offset, int count)
{
return responsestream.read(buffer, offset, count);
}
#endregion
#region write method
public override void write(byte[] buffer, int offset, int count)
{
string sbuffer = system.text.utf8encoding.utf8.getstring(buffer, offset, count);
//得到非法词汇列表，这个可以在数据库或web.config中读取出来
string pattern = @"(非法词汇1|非法词汇2|非法词汇3)";
string[] s = pattern.split(new string[] { "|" }, stringsplitoptions.removeemptyentries);
foreach (string s1 in s)
{
sbuffer = sbuffer.replace(s1, "**");
}
byte[] data = system.text.utf8encoding.utf8.getbytes(sbuffer);
responsestream.write(data, 0, data.length);
}
#endregion
}

然后再global.asax文件中，添加如下代码：
[code]
public void application_beginrequest(){
response.filter = new responsefilter(response.filter);
}
ok,测试一下吧！