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
复制代码 代码如下:
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！