本篇使用java自帶的MessageDigest實現對文本的md5加密算法，具體代碼如下：
/** *@Description: 將字符串轉化為MD5 */ package cn.yicha.novel.util; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class ParseMD5 { /** * @param str * @return * @Description: 32位小寫MD5 */ public static String parseStrToMd5L32(String str){ String reStr = null; try { MessageDigest md5 = MessageDigest.getInstance("MD5"); byte[] bytes = md5.digest(str.getBytes()); StringBuffer stringBuffer = new StringBuffer(); for (byte b : bytes){ int bt = b&0xff; if (bt < 16){ stringBuffer.append(0); } stringBuffer.append(Integer.toHexString(bt)); } reStr = stringBuffer.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return reStr; } /** * @param str * @return * @Description: 32位大寫MD5 */ public static String parseStrToMd5U32(String str){ String reStr = parseStrToMd5L32(str); if (reStr != null){ reStr = reStr.toUpperCase(); } return reStr; } /** * @param str * @return * @Description: 16位小寫MD5 */ public static String parseStrToMd5U16(String str){ String reStr = parseStrToMd5L32(str); if (reStr != null){ reStr = reStr.toUpperCase().substring(8, 24); } return reStr; } /** * @param str * @return * @Description: 16位大寫MD5 */ public static String parseStrToMd5L16(String str){ String reStr = parseStrToMd5L32(str); if (reStr != null){ reStr = reStr.substring(8, 24); } return reStr; } }第二種情況：在進行Java軟件開發過程中，難免會對一些數據進行加密，因此Java中提供了自帶的MessageDigest實現對文本的加密算法，下面是一個對文本進行加密的MD5加密工具類代碼示例：
Java中的MD5加密算法完整版：
package net.yuerwan.commons.util;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import org.apache.commons.lang.StringUtils;public class MD5Util {/*** 1.對文本進行32位小寫MD5加密* @param plainText 要進行加密的文本* @return 加密後的內容*/public static String textToMD5L32(String plainText){String result = null;//首先判斷是否為空if(StringUtils.isBlank(plainText)){return null;}try{//首先進行實例化和初始化MessageDigest md = MessageDigest.getInstance("MD5");//得到一個操作系統默認的字節編碼格式的字節數組byte[] btInput = plainText.getBytes();//對得到的字節數組進行處理md.update(btInput);//進行哈希計算並返回結果byte[] btResult = md.digest();//進行哈希計算後得到的數據的長度StringBuffer sb = new StringBuffer();for(byte b : btResult){int bt = b&0xff;if(bt<16){sb.append(0);}sb.append(Integer.toHexString(bt));}result = sb.toString();}catch(NoSuchAlgorithmException e){e.printStackTrace();}return result;}/*** 2.對文本進行32位MD5大寫加密* @param plainText 要進行加密的文本* @return 加密後的內容*/public static String textToMD5U32(String plainText){if(StringUtils.isBlank(plainText)){return null;}String result = textToMD5L32(plainText);return result.toUpperCase();}第三種情況： MD5加密算法的java實現
package other;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;/* * MD5 算法*/public class MD5 { // 全局數組private final static String[] strDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; public MD5() { } // 返回形式為數字跟字符串private static String byteToArrayString(byte bByte) { int iRet = bByte; // System.out.println("iRet="+iRet); if (iRet < 0) { iRet += 256; } int iD1 = iRet / 16; int iD2 = iRet % 16; return strDigits[iD1] + strDigits[iD2]; } // 返回形式只為數字private static String byteToNum(byte bByte) { int iRet = bByte; System.out.println("iRet1=" + iRet); if (iRet < 0) { iRet += 256; } return String.valueOf(iRet); } // 轉換字節數組為16進製字串private static String byteToString(byte[] bByte) { StringBuffer sBuffer = new StringBuffer(); for (int i = 0; i < bByte.length; i++) { sBuffer.append(byteToArrayString(bByte[i])); } return sBuffer.toString(); } public static String GetMD5Code(String strObj) { String resultString = null; try { resultString = new String(strObj); MessageDigest md = MessageDigest.getInstance("MD5"); // md.digest() 該函數返回值為存放哈希值結果的byte數組resultString = byteToString(md.digest(strObj.getBytes())); } catch (NoSuchAlgorithmException ex) { ex.printStackTrace(); } return resultString; } public static void main(String[] args) { MD5 getMD5 = new MD5(); System.out.println(getMD5.GetMD5Code("000000")); }}