1.MD5加密，常用于加密用户名密码，当用户验证时。
protectedbyte[]encrypt(byte[]obj){try{MessageDigestmd5=MessageDigest.getInstance("MD5");md5.update(obj);returnmd5.digest();}catch(NoSuchAlgorithmExceptione){e.printStackTrace();}}
2.SHA加密，与MD5相似的用法，只是两者的算法不同。
protectedbyte[]encrypt(byte[]obj){try{MessageDigestsha=MessageDigest.getInstance("SHA");sha.update(obj);returnsha.digest();}catch(NoSuchAlgorithmExceptione){e.printStackTrace();}}
3.RSA加密，RAS加密允许解密。常用于文本内容的加密。
importjava.security.KeyPair;importjava.security.KeyPairGenerator;importjava.security.interfaces.RSAPrivateKey;importjava.security.interfaces.RSAPublicKey;importjavax.crypto.Cipher;/***//***RSAEncrypt**@authormaqujun*@see*/publicclassRSAEncrypt{/***//***MainmethodforRSAEncrypt.*@paramargs*/publicstaticvoidmain(String[]args){try...{RSAEncryptencrypt=newRSAEncrypt();StringencryptText="encryptText";KeyPairGeneratorkeyPairGen=KeyPairGenerator.getInstance("RSA");keyPairGen.initialize(1024);KeyPairkeyPair=keyPairGen.generateKeyPair();//GeneratekeysRSAPrivateKeyprivateKey=(RSAPrivateKey)keyPair.getPrivate();RSAPublicKeypublicKey=(RSAPublicKey)keyPair.getPublic();byte[]e=encrypt.encrypt(publicKey,encryptText.getBytes());byte[]de=encrypt.decrypt(privateKey,e);System.out.println(encrypt.bytesToString(e));System.out.println(encrypt.bytesToString(de));}catch(Exceptione){e.printStackTrace();}}/***//***ChangebytearraytoString.*@returnbyte[]*/protectedStringbytesToString(byte[]encrytpByte){Stringresult="";for(Bytebytes:encrytpByte){result+=(char)bytes.intValue();}returnresult;}/***//***EncryptString.*@returnbyte[]*/protectedbyte[]encrypt(RSAPublicKeypublicKey,byte[]obj){if(publicKey!=null){try...{Ciphercipher=Cipher.getInstance("RSA");cipher.init(Cipher.ENCRYPT_MODE,publicKey);returncipher.doFinal(obj);}catch(Exceptione){e.printStackTrace();}}returnnull;}/***//***Basicdecryptmethod*@returnbyte[]*/protectedbyte[]decrypt(RSAPrivateKeyprivateKey,byte[]obj){if(privateKey!=null){try{Ciphercipher=Cipher.getInstance("RSA");cipher.init(Cipher.DECRYPT_MODE,privateKey);returncipher.doFinal(obj);}catch(Exceptione){e.printStackTrace();}}returnnull;}}
