1. 生成一个Java项目 Test

2. 在这个项目下生成两个package
  org.moss.jdj.codec 和 org.moss.jdj.dbcp

3. 把 commons-pool-1.3.jar 和 commons-dbcp-1.2.1.jar 放到 Test 的 classpath 上

4. 把下面这个 Class 放到 org.moss.jdj.dbcp 下:
Java code
package org.moss.jdj.dbcp;

import java.util.Enumeration;
import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.Name;
import javax.naming.RefAddr;
import javax.naming.Reference;
import javax.naming.StringRefAddr;

import org.apache.commons.dbcp.BasicDataSourceFactory;
import org.moss.jdj.codec.Base64Coder;

public class EncryptedDataSourceFactory extends BasicDataSourceFactory
{

    public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable environment)
    throws Exception      
    {
        if (obj instanceof Reference)
        {
            setUsername((Reference)obj);
            setPassword((Reference)obj);        
        }   
        return super.getObjectInstance(obj, name, nameCtx, environment);
    }

    private void setUsername(Reference ref)
    throws Exception {
        findDecryptAndReplace("username", ref);        
    }
   
    private void setPassword(Reference ref)
    throws Exception {
        findDecryptAndReplace("password", ref);
    }

   
    private void findDecryptAndReplace(String refType, Reference ref)
    throws Exception {
        int idx = find(refType, ref);
        String decrypted = decrypt(idx, ref);
        replace(idx, refType, decrypted, ref);
    }
   
    private void replace(int idx, String refType, String newValue, Reference ref)
    throws Exception
    {
        ref.remove(idx);
        ref.add(idx, new StringRefAddr(refType, newValue));
    }
   
    private String decrypt(int idx, Reference ref)
    throws Exception {
        return Base64Coder.decode(
            ref.get(idx).getContent().toString()
        );
    }
   
    private int find(String addrType, Reference ref)
    throws Exception
    {
        Enumeration enu = ref.getAll();
        for (int i=0; enu.hasMoreElements(); i++) {
            RefAddr addr = (RefAddr)enu.nextElement();
            if (addr.getType().compareTo(addrType) == 0) {
                return i;
            }
        }
        throw new Exception(
            "The \""+addrType+"\" name/value pair was not found"
            + " in the Reference object.  The reference Object is"
            + " " + ref.toString()
        );
    }
     
     
}



5. 把下面这个 Class 放到 org.moss.jdj.codec 下:
Java code
package org.moss.jdj.codec;

public class Base64Coder {

// Mapping table from 6-bit nibbles to Base64 characters.
private static char[]    map1 = new char[64];
   static {
      int i=0;
      for (char c='A'; c<='Z'; c++) map1[i++] = c;
      for (char c='a'; c<='z'; c++) map1[i++] = c;
      for (char c='0'; c<='9'; c++) map1[i++] = c;
      map1[i++] = '+'; map1[i++] = '/'; }

// Mapping table from Base64 characters to 6-bit nibbles.
private static byte[]    map2 = new byte[128];
   static {
      for (int i=0; i      for (int i=0; i<64; i++) map2[map1[i]] = (byte)i; }

/**
* Encodes a string into Base64 format.
* No blanks or line breaks are inserted.
* @param s  a String to be encoded.
* @return   A String with the Base64 encoded data.
*/
public static String encode (String s) {
   return new String(encode(s.getBytes())); }

/**
* Encodes a byte array into Base64 format.
* No blanks or line breaks are inserted.
* @param in  an array containing the data bytes to be encoded.
* @return    A character array with the Base64 encoded data.
*/
public static char[] encode (byte[] in) {
   int iLen = in.length;
   int DataLen = (iLen*4+2)/3;       // output length without padding
   int Len = ((iLen+2)/3)*4;         // output length including padding
   char[] ut = new char[oLen];
   int ip = 0;
   int p = 0;
   while (ip < iLen) {
      int i0 = in[ip++] & 0xff;
      int i1 = ip < iLen ? in[ip++] & 0xff : 0;
      int i2 = ip < iLen ? in[ip++] & 0xff : 0;
      int o0 = i0 >>> 2;
      int o1 = ((i0 &   3) << 4) | (i1 >>> 4);
      int o2 = ((i1 & 0xf) << 2) | (i2 >>> 6);
      int o3 = i2 & 0x3F;
      out[op++] = map1[o0];
      out[op++] = map1[o1];
      out[op] = op < oDataLen ? map1[o2] : '='; op++;
      out[op] = op < oDataLen ? map1[o3] : '='; op++; }
   return out; }

/**
* Decodes a Base64 string.
* @param s  a Base64 String to be decoded.
* @return   A String containing the decoded data.
* @throws   IllegalArgumentException if the input is not valid Base64 encoded data.
*/
public static String decode (String s) {
   return new String(decode(s.toCharArray())); }

/**
* Decodes Base64 data.
* No blanks or line breaks are allowed within the Base64 encoded data.
* @param in  a character array containing the Base64 encoded data.
* @return    An array containing the decoded data bytes.
* @throws    IllegalArgumentException if the input is not valid Base64 encoded data.
*/
public static byte[] decode (char[] in) {
   int iLen = in.length;
   if (iLen%4 != 0) throw new IllegalArgumentException ("Length of Base64 encoded input string is not a multiple of 4.");
   while (iLen > 0 && in[iLen-1] == '=') iLen--;
   int Len = (iLen*3) / 4;
   byte[] ut = new byte[oLen];
   int ip = 0;
   int p = 0;
   while (ip < iLen) {
      int i0 = in[ip++];
      int i1 = in[ip++];
      int i2 = ip < iLen ? in[ip++] : 'A';
      int i3 = ip < iLen ? in[ip++] : 'A';
      if (i0 > 127 || i1 > 127 || i2 > 127 || i3 > 127)
         throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
      int b0 = map2[i0];
      int b1 = map2[i1];
      int b2 = map2[i2];
      int b3 = map2[i3];
      if (b0 < 0 || b1 < 0 || b2 < 0 || b3 < 0)
         throw new IllegalArgumentException ("Illegal character in Base64 encoded data.");
      int o0 = ( b0       <<2) | (b1>>>4);
      int o1 = ((b1 & 0xf)<<4) | (b2>>>2);
      int o2 = ((b2 &   3)<<6) |  b3;
      out[op++] = (byte)o0;
      if (op      if (op   return out; }

}



6. Export 这个 Java 项目到一个 Jar : password.jar

7. 把 password.jar，commons-pool-1.3.jar 和 commons-dbcp-1.2.1.jar 放到
  TOMCAT_HOME/lib 下

8. 在 Context.xml 里加入如下语句 ：factory="org.moss.jdj.dbcp.EncryptedDataSourceFactory"

9. 在网上随便找个Base64加密网站把你的username和password加密，然后把加密的username和password换到你的context.xml中

10. 重启Tomcat

最后你的context.xml,应该和下面的类似：

    docBase="D:/workspace/BankCheckBusinessInsShow_shenzhen"
    reloadable="true"
    workDir="work/Catalina/localhost/BankCheckBusinessInsShow_shenzhen">
      auth="Container"
    factory="org.moss.jdj.dbcp.EncryptedDataSourceFactory
    name="jdbc/BankCheckBusinessInsShow"
    type="javax.sql.DataSource"
    maxActive="50"
    maxIdle="30"
    username="xxxxxxxx"
    maxWait="5000"
    removeAbandoned="true"
    driverClassName="com.ibm.db2.jcc.DB2Driver"
    password="********"
    url="jdbc:db2://rbht4:50000/pe"/>