/**
* The doPost method of the servlet.

*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

this.doGet(request, response);
}

/**
* Initialization of the servlet.

*
* @throws ServletException
* if an error occure
*/
public void init() throws ServletException {
// Put your code here
}

}

/**
* @author 李国庆
* @company leemenz (C) copyright
* @time Dec 18, 2006 3:58:53 PM
* @version 1.0.0.0
* @package com
*/
package com;

import java.io.IOException;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

/**
* @author Administrator
* 　这个类继承HttpServletResponseWrapper ，并重写相应的方法
*/
public class ReplaceServletWapper extends HttpServletResponseWrapper {

private ReplaceTextStream tpStream;

/**
* @param arg0
*/
public ReplaceServletWapper(HttpServletResponse arg0, String searchText,
String replaceText) throws IOException {
// TODO Auto-generated constructor stub
super((HttpServletResponse)arg0);
tpStream = new ReplaceTextStream(arg0.getOutputStream(),searchText,replaceText);
}

public ServletOutputStream getOutputStream() throws IOException {
return tpStream;
}

}

/**
* @author 李国庆
* @company leemenz (C) copyright
* @time Dec 18, 2006 2:08:18 PM
* @version 1.0.0.0
* @package com
*/
package com;

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;
import javax.servlet.http.HttpServletResponse;

/**
* @author Administrator
*
* 这个类用来过滤留言或者是用户名中的非法内容
*
*/
public class ReplaceTextFilter implements Filter {

private FilterConfig config;

private String searchStr;

private String replaceStr;

/*
* (non-Javadoc)
*
* @see javax.servlet.Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
config = null;
}

/*
* (non-Javadoc)
*
* @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest,
* javax.servlet.ServletResponse, javax.servlet.FilterChain)
*/
public void doFilter(ServletRequest request, ServletResponse response,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
ReplaceServletWapper myWrappered = new ReplaceServletWapper(
(HttpServletResponse) response, searchStr, replaceStr);
config.getServletContext().log(
“ReplaceTextFilter : before called doFilter”);
chain.doFilter(request, myWrappered);
config.getServletContext().log(
“ReplaceTextFilter : after called doFilter”);
myWrappered.getOutputStream().close();
}

/*
* (non-Javadoc)
*
* @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
*/
public void init(FilterConfig arg0) throws ServletException {
// TODO Auto-generated method stub
this.config = arg0;
this.searchStr = config.getInitParameter(“search”);
this.replaceStr = config.getInitParameter(“replace”);
}

}

/**
* @author 李国庆
* @company leemenz (C) copyright
* @time Dec 18, 2006 3:33:51 PM
* @version 1.0.0.0
* @package com
*/
package com;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.ServletOutputStream;

/**
* @author Administrator
* 这个类继承ServletOutputStream ，并重写相应的方法
*/
public class ReplaceTextStream extends ServletOutputStream {

private OutputStream intStream;

private ByteArrayOutputStream baStream;

private boolean closed = false;

private String newStr;

private String oldStr;

/**
*
*/
public ReplaceTextStream(OutputStream outStream, String strSearch,
String strReplace) {
// TODO Auto-generated constructor stub
intStream = outStream;
baStream = new ByteArrayOutputStream();
oldStr = strSearch;
newStr = strReplace;
}

/*
* (non-Javadoc)
*
* @see java.io.OutputStream#write(int)
*/
public void write(int b) throws IOException {
// TODO Auto-generated method stub
baStream.write(b);
}

/**
* 重写方法
*/
public void println(String s) throws IOException {
s = s + “\n”;
byte[] bs = s.getBytes();
baStream.write(bs);
}

/**
* 重写方法
*/
public void close() throws IOException {
if (!closed) {
processStream();
intStream.close();
closed = true;
}
}

/**
* 重写方法
*/
public void flush() throws IOException {
if (baStream.size() != 0) {
processStream();
baStream = new ByteArrayOutputStream();
}
}

/**
* 重写 processStream 方法
*
* @throws IOException
*/
public void processStream() throws IOException {
intStream.write(replaceContent(baStream.toByteArray()));
}

/**
* 替换所有的目的词语
*
* @param inBytes
* @return
*/
public byte[] replaceContent(byte[] inBytes) {
String retVal = “”;
String tpString = new String(inBytes);
String srchString = (new String(inBytes)).toLowerCase();
int endBody = srchString.indexOf(oldStr);
if (endBody != -1) {
retVal = tpString.replaceAll(oldStr, newStr);
} else
retVal = tpString;
return retVal.getBytes();
}

}

xmlns=”http://java.sun.com/xml/ns/j2ee”
xmlns:xsi=”http://www.w3.org/2001/XMLSchema-instance”
xsi:schemaLocation=”http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd”>

NoteFilter
com.NoteFilter
blackList 毛泽东

NoteFilter
/servlet/NoteServlet

ReplaceTextFilter
com.ReplaceTextFilter
search 法轮功
replace 邪教

ReplaceTextFilter
/servlet/NoteServlet

NoteServlet
com.NoteServlet

NoteServlet
/servlet/NoteServlet

另外，要看到日志的输出信息，必须确保在server.xml文件中有如下代码：

prefix=”catalina_log.” suffix=”.txt”
timestamp=”true”/>

enjoy it!!! 🙂