今天,因为要用到一个加密的过程,所以参照了一些网络上的内容,写了这个md5算法

package com.change.date;
/**
*Description: MD5加密算法
*
*Copyright: Copyright (c) 2005
*
*Company:  leemenz
*
* @author    李国庆
* @version   1.0.0.0
*/
public class MD5 {
/** 下面这些S11-S44实际上是一个4*4的矩阵,在原始的C实现中是用#define 实现的,
 * 这里把它们实现成为static final是表示了只读,切能在同一个进程空间内的多个
 * Instance间共享
 */
static final int S11 = 7;
static final int S12 = 12;
static final int S13 = 17;
static final int S14 = 22;

static final int S21 = 5;
static final int S22 = 9;
static final int S23 = 14;
static final int S24 = 20;

static final int S31 = 4;
static final int S32 = 11;
static final int S33 = 16;
static final int S34 = 23;

static final int S41 = 6;
static final int S42 = 10;
static final int S43 = 15;
static final int S44 = 21;

static final byte[] PADDING = { -128, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

/** 下面的三个成员是MD5计算过程中用到的3个核心数据,在原始的C实现中
 * 被定义到MD5_CTX结构中
 */
private long[] state = new long[4];  // state (ABCD)
private long[] count = new long[2];  // number of bits, modulo 2^64 (lsb first)
private byte[] buffer = new byte[64]; // input buffer

/** digestHexStr是MD5的唯一一个公共成员,是最新一次计算结果的
 *  16进制ASCII表示.
 */
public String digestHexStr;

/** digest,是最新一次计算结果的2进制内部表示,表示128bit的MD5值.
 */
private byte[] digest = new byte[16];

/** getMD5ofStr是类MD5最主要的公共方法,入口参数是你想要进行MD5变换的字符串
 *  返回的是变换完的结果,这个结果是从公共成员digestHexStr取得的.
 */
public String getMD5ofStr(String inbuf) {
 md5Init();
 md5Update(inbuf.getBytes(), inbuf.length());
 md5Final();
 digestHexStr = "";
 for (int i = 0; i < 16; i++) {
  digestHexStr += byteHEX(digest);
 }
 return digestHexStr;
}

// 这是MD5这个类的标准构造函数,JavaBean要求有一个public的并且没有参数的构造函数
public MD5() {
 md5Init();

 return;
}

/** md5Init是一个初始化函数,初始化核心变量,装入标准的幻数
 */
private void md5Init() {
 count[0] = 0L;
 count[1] = 0L;
 ///* Load magic initialization constants.

 state[0] = 0x67452301L;
 state[1] = 0xefcdab89L;
 state[2] = 0x98badcfeL;
 state[3] = 0x10325476L;

 return;
}

/** F, G, H ,I 是4个基本的MD5函数,在原始的MD5的C实现中,由于它们是
 *  简单的位运算,可能出于效率的考虑把它们实现成了宏,在java中,我们把它们
 *  实现成了private方法,名字保持了原来C中的。
 */
private long F(long x, long y, long z) {
 return (x & y) | ((~x) & z);
}
private long G(long x, long y, long z) {
 return (x & z) | (y & (~z));
}
private long H(long x, long y, long z) {
 return x ^ y ^ z;
}
private long I(long x, long y, long z) {
 return y ^ (x | (~z));
}

/** FF,GG,HH和II将调用F,G,H,I进行近一步变换
 *  FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
 *  Rotation is separate from addition to prevent recomputation.
 */
private long FF(long a, long b, long c, long d, long x, long s,long ac) {
 a += F (b, c, d) + x + ac;
 a = ((int) a << s) | ((int) a >>> (32 - s));
 a += b;
 return a;
}

private long GG(long a, long b, long c, long d, long x, long s,long ac) {
 a += G (b, c, d) + x + ac;
 a = ((int) a << s) | ((int) a >>> (32 - s));
 a += b;
 return a;
}
private long HH(long a, long b, long c, long d, long x, long s,long ac) {
 a += H (b, c, d) + x + ac;
 a = ((int) a << s) | ((int) a >>> (32 - s));
 a += b;
 return a;
}
private long II(long a, long b, long c, long d, long x, long s,long ac) {
 a += I (b, c, d) + x + ac;
 a = ((int) a << s) | ((int) a >>> (32 - s));
 a += b;
 return a;
}

/** md5Update是MD5的主计算过程,inbuf是要变换的字节串,inputlen是长度,这个
 *  函数由getMD5ofStr调用,调用之前需要调用md5init,因此把它设计成private的
 */
private void md5Update(byte[] inbuf, int inputLen) {
 int i, index, partLen;
 byte[] block = new byte[64];
 index = (int)(count[0] >>> 3) & 0x3F;
 // /* Update number of bits */
 if ((count[0] += (inputLen << 3)) < (inputLen << 3))
  count[1]++;
 count[1] += (inputLen >>> 29);

 partLen = 64 - index;

 // Transform as many times as possible.
 if (inputLen >= partLen) {
  md5Memcpy(buffer, inbuf, index, 0, partLen);
  md5Transform(buffer);

  for (i = partLen; i + 63 < inputLen; i += 64) {

   md5Memcpy(block, inbuf, 0, i, 64);
   md5Transform (block);
  }
  index = 0;

 } else
  i = 0;

 ///* Buffer remaining input */
 md5Memcpy(buffer, inbuf, index, i, inputLen - i);
}

/**md5Final整理和填写输出结果
 */
private void md5Final () {
 byte[] bits = new byte[8];
 int index, padLen;

 ///* Save number of bits */
 Encode (bits, count, 8);

 ///* Pad out to 56 mod 64.
 index = (int)(count[0] >>> 3) & 0x3f;
 padLen = (index < 56) ? (56 - index) : (120 - index);
 md5Update (PADDING, padLen);

 ///* Append length (before padding) */
 md5Update(bits, 8);

 ///* Store state in digest */
 Encode (digest, state, 16);
}

/** md5Memcpy是一个内部使用的byte数组的块拷贝函数,从input的inpos开始把len长度的
 *  字节拷贝到output的outpos位置开始
 */
private void md5Memcpy (byte[] output, byte[] input,int outpos, int inpos, int len){
 int i;

 for (i = 0; i < len; i++)
  output[outpos + i] = input[inpos + i];
}

/** md5Transform是MD5核心变换程序,有md5Update调用,block是分块的原始字节
 */
private void md5Transform (byte block[]) {
 long a = state[0], b = state[1], c = state[2], d = state[3];
 long[] x = new long[16];

 Decode (x, block, 64);

 /* Round 1 */
 a = FF (a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */
 d = FF (d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */
 c = FF (c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */
 b = FF (b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */
 a = FF (a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */
 d = FF (d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */
 c = FF (c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */
 b = FF (b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */
 a = FF (a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */
 d = FF (d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */
 c = FF (c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */
 b = FF (b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */
 a = FF (a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */
 d = FF (d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */
 c = FF (c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */
 b = FF (b, c, d, a, x[15], S14, 0x49b40821L); /* 16 */

 /* Round 2 */
 a = GG (a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */
 d = GG (d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */
 c = GG (c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */
 b = GG (b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */
 a = GG (a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */
 d = GG (d, a, b, c, x[10], S22, 0x2441453L); /* 22 */
 c = GG (c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */
 b = GG (b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */
 a = GG (a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */
 d = GG (d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */
 c = GG (c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */
 b = GG (b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */
 a = GG (a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */
 d = GG (d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */
 c = GG (c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */
 b = GG (b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 */

 /* Round 3 */
 a = HH (a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */
 d = HH (d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */
 c = HH (c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */
 b = HH (b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */
 a = HH (a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */
 d = HH (d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */
 c = HH (c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */
 b = HH (b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */
 a = HH (a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */
 d = HH (d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */
 c = HH (c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */
 b = HH (b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */
 a = HH (a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */
 d = HH (d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */
 c = HH (c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */
 b = HH (b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 */

 /* Round 4 */
 a = II (a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */
 d = II (d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */
 c = II (c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */
 b = II (b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */
 a = II (a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */
 d = II (d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */
 c = II (c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */
 b = II (b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */
 a = II (a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */
 d = II (d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */
 c = II (c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */
 b = II (b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */
 a = II (a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */
 d = II (d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */
 c = II (c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */
 b = II (b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */

 state[0] += a;
 state[1] += b;
 state[2] += c;
 state[3] += d;
}

/** Encode把long数组按顺序拆成byte数组,因为java的long类型是64bit的,
 *  只拆低32bit,以适应原始C实现的用途
 */
private void Encode (byte[] output, long[] input, int len) {
 int i, j;

 for (i = 0, j = 0; j < len; i++, j += 4) {
  output[j] = (byte)(input & 0xffL);
  output[j + 1] = (byte)((input >>> 8) & 0xffL);
  output[j + 2] = (byte)((input >>> 16) & 0xffL);
  output[j + 3] = (byte)((input >>> 24) & 0xffL);
 }
}

/** Decode把byte数组按顺序合成成long数组,因为java的long类型是64bit的,
 *  只合成低32bit,高32bit清零,以适应原始C实现的用途
 */
private void Decode (long[] output, byte[] input, int len) {
 int i, j;

 for (i = 0, j = 0; j < len; i++, j += 4)
  output = b2iu(input[j]) |
   (b2iu(input[j + 1]) << 8) |
   (b2iu(input[j + 2]) << 16) |
   (b2iu(input[j + 3]) << 24);

  return;
}

/** b2iu是我写的一个把byte按照不考虑正负号的原则的"升位"程序,因为java没有unsigned运算
 */
public static long b2iu(byte b) {
 return b < 0 ? b & 0x7F + 128 : b;
}

/** byteHEX(),用来把一个byte类型的数转换成十六进制的ASCII表示,
 *  因为java中的byte的toString无法实现这一点,我们又没有C语言中的
 *  sprintf(outbuf,"%02X",ib)
 */
 public static String byteHEX(byte ib) {
  char[] Digit = { '0','1','2','3','4','5','6','7','8','9',
   'A','B','C','D','E','F' };
  char [] ob = new char[2];
  ob[0] = Digit[(ib >>> 4) & 0X0F];
  ob[1] = Digit[ib & 0X0F];
  String s = new String(ob);
  return s;
}

public static String toMD5(String source){
 MD5 md5 = new MD5();
 return md5.getMD5ofStr(source);
}
}
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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();
  }
 }
}
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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!!! 🙂

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