md5应用

/*

　　md5工具类

*/

public class MD5Util {

/**全局数组**/
private final static String[] strDigits = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F" };

/**
* 返回形式为数字跟字符串
* @param bByte
* @return
*/
private static String byteToArrayString(byte bByte) {
int iRet = bByte;
if (iRet < 0) {
iRet += 256;
}
int iD1 = iRet / 16;
int iD2 = iRet % 16;
return strDigits[iD1] + strDigits[iD2];
}

/**
* 转换字节数组为16进制字串
* @param bByte
* @return
*/
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();
}
/**
* MD5加密
* @param str 待加密的字符串
* @return
*/
public static String GetMD5Code(String str) {
String result = null;
try {
result = new String(str);
MessageDigest md = MessageDigest.getInstance("MD5");
result = byteToString(md.digest(str.getBytes()));
} catch (NoSuchAlgorithmException ex) {
ex.printStackTrace();
}
return result;
}
public static String md5(String str) {
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(str.getBytes());
byte b[] = md.digest();

int i;

StringBuffer buf = new StringBuffer("");
for (int offset = 0; offset < b.length; offset++) {
i = b[offset];
if (i < 0)
i += 256;
if (i < 16)
buf.append("0");
buf.append(Integer.toHexString(i));
}
str = buf.toString();
} catch (Exception e) {
e.printStackTrace();

}
return str;
}
/**
* MD5加密
* @param str 待加密的字符串
* @param lowerCase 小写
* @return
*/
public static String GetMD5Code(String str,boolean lowerCase) {
String result = null;
try {
result = new String(str);
MessageDigest md = MessageDigest.getInstance("MD5");
result = byteToString(md.digest(str.getBytes()));
if(lowerCase){
result = result.toLowerCase();
}
} catch (NoSuchAlgorithmException ex) {
ex.printStackTrace();
}
return result;
}
public static void main(String[] args) {

}
}

测试方法

public class Test {

@org.junit.Test
public void testMd5() {
String str = "D4762CBC5DF6216428E6B32512BD7C82";
String string = MD5Util.GetMD5Code(str);
System.out.println(string);
}
@org.junit.Test
public void isRightByMd5() {
String st1 = "A4A2D722647A81E94218263A76359DA1";
String st2 = "D4762CBC5DF6216428E6B32512BD7C82";
if (MD5Util.GetMD5Code(st2).equals(st1)) {
System.out.println("yes");
}else{
System.err.println("no");
}
}
}