因为要用到,所以在网上找了资料后,写了个。:)

 
DESPlus.java

/**
 * @author    李国庆
 * @company   leemenz (C) copyright
 * @time      Nov 1, 2006  10:18:41 AM
 * @version   1.0.0.0
 * @package   com.des
 */
package com.des;

import java.security.*;
import javax.crypto.*;

public class DESPlus {
 private static String strDefaultKey = "national";

 private Cipher encryptCipher = null;

 private Cipher decryptCipher = null;

 /**
  * 将byte数组转换为表示16进制值的字符串, 如:byte[]{8,18}转换为:0813, 和public static byte[]
  * hexStr2ByteArr(String strIn) 互为可逆的转换过程
  * 
  * @param arrB
  *            需要转换的byte数组
  * @return 转换后的字符串
  * @throws Exception
  *             本方法不处理任何异常,所有异常全部抛出
  */
 public static String byteArr2HexStr(byte[] arrB) throws Exception {
  int iLen = arrB.length;
  // 每个byte用两个字符才能表示,所以字符串的长度是数组长度的两倍
  StringBuffer sb = new StringBuffer(iLen * 2);
  for (int i = 0; i < iLen; i++) {
   int intTmp = arrB<i>;
   // 把负数转换为正数
   while (intTmp < 0) {
    intTmp = intTmp + 256;
   }
   // 小于0F的数需要在前面补0
   if (intTmp < 16) {
    sb.append("0");
   }
   sb.append(Integer.toString(intTmp, 16));
  }
  return sb.toString();
 }

 /**
  * 将表示16进制值的字符串转换为byte数组, 和public static String byteArr2HexStr(byte[] arrB)
  * 互为可逆的转换过程
  * 
  * @param strIn
  *            需要转换的字符串
  * @return 转换后的byte数组
  * @throws Exception
  *             本方法不处理任何异常,所有异常全部抛出
  * @author <a href="mailto:leo841001@163.com">LiGuoQing</a>
  */
 public static byte[] hexStr2ByteArr(String strIn) throws Exception {
  byte[] arrB = strIn.getBytes();
  int iLen = arrB.length;

  // 两个字符表示一个字节,所以字节数组长度是字符串长度除以2
  byte[] arrOut = new byte[iLen / 2];
  for (int i = 0; i < iLen; i = i + 2) {
   String strTmp = new String(arrB, i, 2);
   arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
  }
  return arrOut;
 }

 /**
  * 默认构造方法,使用默认密钥
  * 
  * @throws Exception
  */
 public DESPlus() throws Exception {
  this(strDefaultKey);
 }

 /**
  * 指定密钥构造方法
  * 
  * @param strKey
  *            指定的密钥
  * @throws Exception
  */
 public DESPlus(String strKey) throws Exception {
  Security.addProvider(new com.sun.crypto.provider.SunJCE());
  Key key = getKey(strKey.getBytes());

  encryptCipher = Cipher.getInstance("DES");
  encryptCipher.init(Cipher.ENCRYPT_MODE, key);

  decryptCipher = Cipher.getInstance("DES");
  decryptCipher.init(Cipher.DECRYPT_MODE, key);
 }

 /**
  * 加密字节数组
  * 
  * @param arrB
  *            需加密的字节数组
  * @return 加密后的字节数组
  * @throws Exception
  */
 public byte[] encrypt(byte[] arrB) throws Exception {
  return encryptCipher.doFinal(arrB);
 }

 /**
  * 加密字符串
  * 
  * @param strIn
  *            需加密的字符串
  * @return 加密后的字符串
  * @throws Exception
  */
 public String encrypt(String strIn) throws Exception {
  return byteArr2HexStr(encrypt(strIn.getBytes()));
 }

 /**
  * 解密字节数组
  * 
  * @param arrB
  *            需解密的字节数组
  * @return 解密后的字节数组
  * @throws Exception
  */
 public byte[] decrypt(byte[] arrB) throws Exception {
  return decryptCipher.doFinal(arrB);
 }

 /**
  * 解密字符串
  * 
  * @param strIn
  *            需解密的字符串
  * @return 解密后的字符串
  * @throws Exception
  */
 public String decrypt(String strIn) throws Exception {
  return new String(decrypt(hexStr2ByteArr(strIn)));
 }

 /**
  * 从指定字符串生成密钥,密钥所需的字节数组长度为8位 不足8位时后面补0,超出8位只取前8位
  * 
  * @param arrBTmp
  *            构成该字符串的字节数组
  * @return 生成的密钥
  * @throws java.lang.Exception
  */
 private Key getKey(byte[] arrBTmp) throws Exception {
  // 创建一个空的8位字节数组(默认值为0)
  byte[] arrB = new byte[8];

  // 将原始字节数组转换为8位
  for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
   arrB<i> = arrBTmp<i>;
  }

  // 生成密钥
  Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");

  return key;
 }
}

测试程序  Test.java

/**
 * @author    李国庆
 * @company   leemenz (C) copyright
 * @time      Nov 1, 2006  10:24:06 AM
 * @version   1.0.0.0
 * @package   com.des
 */
package com.des;

/**
 * @author Administrator
 *
 */
public class Test {

 /**
  * @param args
  */
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  try {
   String test = "Hellow Word!";
   //DESPlus des = new DESPlus();//默认密钥
   DESPlus des = new DESPlus("leemenz");//自定义密钥
   System.out.println("加密前的字符:"+test);
   System.out.println("加密后的字符:"+des.encrypt(test));
   System.out.println("解密后的字符:"+des.decrypt(des.encrypt(test)));
  } catch (Exception e) {
   // TODO: handle exception
   e.printStackTrace();
  }
 }
}

也是一个朋友要求帮忙,在整个网站的访问期间要过滤掉例如“法轮功”的非法字符,所以帮忙写了个。一下是一个测试的源程序。tomcat 5.0.28 ,  windows 2000 sp4 , jdk1.4中测试通过 Eclipse下工程源码下载(将文件后面的.jpg去掉即可,是个压缩包)


/**
* @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 java.io.PrintWriter;

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.HttpServletRequest;

/**
* @author Administrator
*
* 这个过滤器用来过滤黑名单中的用户不能留言
*
*/
public class NoteFilter implements Filter {

private FilterConfig config = null;

private String blackList = null;

/*
* (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
String username = request.getParameter(“username”);
if (username != null)
username = new String(request.getParameter(“username”).getBytes(
“ISO8859-1”), “GB2312”);
if (username != null && username.indexOf(blackList) != -1) {
response.setContentType(“text/html;charset=GB2312”);
PrintWriter out = response.getWriter();
out.println(““);
out.println(“

对不起,” + username + “,您没有留言的权限!”);
out.println(“

“);
out.flush();
return;
}

long before = System.currentTimeMillis();
config.getServletContext()
.log(“NoteFilter:before call chain.Filter();”);
chain.doFilter(request, response);
config.getServletContext().log(“NoteFilter:after call chain.Filter();”);
long end = System.currentTimeMillis();
String name = “”;
if (request instanceof javax.servlet.http.HttpServletRequest) {
name = ((HttpServletRequest) request).getRequestURI();
}
config.getServletContext().log(
“NoteFilter ” + name + ” : ” + (end – before) + ” ms”);
}

/*
* (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.blackList = config.getInitParameter(“blackList”);
}

}

/**
* @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.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/*
*测试页面
*/
public class NoteServlet extends HttpServlet {

public static final String CONTENT_TYPE = “text/html;charset=GB2312”;

/**
* Constructor of the object.
*/
public NoteServlet() {
super();
}

/**
* Destruction of the servlet.

*/
public void destroy() {
super.destroy(); // Just puts “destroy” string in log
// Put your code here
}

/**
* The doDelete method of the servlet.

*
* This method is called when a HTTP delete request is received.
*
* @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 doDelete(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {

// Put your code here
}

/**
* The doGet method of the servlet.

*
* This method is called when a form has its tag value method equals to get.
*
* @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 doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

response.setContentType(CONTENT_TYPE);
ServletOutputStream out = response.getOutputStream();
out
.println(““);
out.println(““);
out.println(” 留言簿“);
out.println(” “);

String name = request.getParameter(“username”);
String content = request.getParameter(“content”);

if (name != null)
name = new String(name.getBytes(“ISO-8859-1”), “GB2312”);
if (content != null)
content = new String(content.getBytes(“ISO-8859-1”), “GB2312”);

if (content != null)
out.println(“

” + name + “的留言为:” + content);

out.println(“

+ request.getContextPath() + “/servlet/NoteServlet\”>”);
out.println(“姓名:
“);
out
.println(“内容:
“);
out.println(““);
out.println(“
“);
out.println(” “);
out.println(““);
out.flush();
out.close();
}

/**
* 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!!! 🙂