使用Java MD5 為檔案和字串加密

標籤：java

加密工具類

package com.kaige123.util; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; import java.security.MessageDigest; /**  * MD5文字和檔案加密<br>  * http://www.kaige123.com  * @author 凱哥  */ public class MD5Util {          //16進位          protected static char hex[] = {                             ’0’, ’1’, ’2’, ’3’, ’4’, ’5’, ’6’,’7’, ’8’, ’9’, ’A’, ’B’, ’C’, ’D’, ’E’, ’F’};          protected static MessageDigest messagedigest = null;          static {                    try {                             //得到MD5執行個體                             messagedigest = MessageDigest.getInstance("MD5");                    } catch (Exception e) {                    }          }          //得到檔案MD5鑰匙          public static String getFileMD5String(File file) throws IOException {                    FileInputStream in = new FileInputStream(file);                    FileChannel ch = in.getChannel();                    MappedByteBuffer byteBuffer =                                      ch.map(FileChannel.MapMode.READ_ONLY, 0,                                      file.length());                    messagedigest.update(byteBuffer);                    return bufferToHex(messagedigest.digest());          }          //得到MD5字串鑰匙          public static String getMD5String(String s) {                    return getMD5String(s.getBytes());          }          public static String getMD5String(byte[] bytes) {                    messagedigest.update(bytes);                    return bufferToHex(messagedigest.digest());          }          private static String bufferToHex(byte bytes[]) {                    return bufferToHex(bytes, 0, bytes.length);          }          private static String bufferToHex(byte bytes[], int m, int n) {                    StringBuffer stringbuffer = new StringBuffer(2 * n);                    int k = m + n;                    for (int l = m; l < k; l++) {                             appendHexPair(bytes[l], stringbuffer);                    }                    return stringbuffer.toString();          }          private static void appendHexPair(byte bt, StringBuffer stringbuffer) {                    char c0 = hex[(bt & 0xf0) >> 4];                    char c1 = hex[bt & 0xf];                    stringbuffer.append(c0);                    stringbuffer.append(c1);          } }

 

測試類別

package com.kaige123.util; import java.io.File; import java.io.IOException; /**  * 測試類別  * @author 凱哥  */ public class Test {          public static void main(String[] args) throws IOException {                    //得到字串MD5                    String md5str=MD5Util.getMD5String("凱哥是個胖子");                    System.out.println(md5str);                             //得到檔案的MD5                    String filemd5str=MD5Util.getFileMD5String(new File("c:/kaige/a.txt"));                    System.out.println(filemd5str);          } }

 

使用Java MD5 為檔案和字串加密