概念不再罗嗦，百度。主要就是三步：创建Cipher对象，初始化Cipher，加密解密

AES加密算法模式有四种：ECB、CBC、CFB、OFB

要想AES加密，至少需要一个16位的密钥，如果是非ECB模式的加密，至少还得需要密钥偏移量。

package com.example.xiaobai.aes;

import android.util.Log;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;

/**
 * Created by xiaobai on 2017/12/7/007.
 */

public class AES {
    private final String KEY_GENERATION_ALG = "PBEWITHSHAANDTWOFISH-CBC";
    // private final String KEY_GENERATION_ALG = "PBKDF2WithHmacSHA1";
    private final int HASH_ITERATIONS = 10000;
    private final int KEY_LENGTH = 128;
    private char[] humanPassphrase = { 'P', 'e', 'r', ' ', 'v', 'a', 'l', 'l',
            'u', 'm', ' ', 'd', 'u', 'c', 'e', 's', ' ', 'L', 'a', 'b', 'a',
            'n', 't' };// per vallum duces labant
    private byte[] salt = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0xA, 0xB, 0xC, 0xD,
            0xE, 0xF }; // must save this for next time we want the key

    private PBEKeySpec myKeyspec = new PBEKeySpec(humanPassphrase, salt,
            HASH_ITERATIONS, KEY_LENGTH);
    private final String CIPHERMODEPADDING = "AES/CBC/PKCS5Padding";// AES/CBC/PKCS7Padding

    private SecretKeyFactory keyfactory = null;
    private SecretKey sk = null;
    private SecretKeySpec skforAES = null;
    private static String ivParameter = "1234567890123456";// 密钥默认偏移，可更改
    // private byte[] iv = { 0xA, 1, 0xB, 5, 4, 0xF, 7, 9, 0x17, 3, 1, 6, 8,
    // 0xC,
    // 0xD, 91 };
    private byte[] iv = ivParameter.getBytes();
    private IvParameterSpec IV;
    String sKey = "1234567890123456";// key必须为16位，可更改为自己的key

    public AES() {
        try {
            keyfactory = SecretKeyFactory.getInstance(KEY_GENERATION_ALG);
            sk = keyfactory.generateSecret(myKeyspec);
        } catch (NoSuchAlgorithmException nsae) {
            Log.e("AESdemo",
                    "no key factory support for PBEWITHSHAANDTWOFISH-CBC");
        } catch (InvalidKeySpecException ikse) {
            Log.e("AESdemo", "invalid key spec for PBEWITHSHAANDTWOFISH-CBC");
        }

        // This is our secret key. We could just save this to a file instead of
        // regenerating it
        // each time it is needed. But that file cannot be on the device (too
        // insecure). It could
        // be secure if we kept it on a server accessible through https.

        // byte[] skAsByteArray = sk.getEncoded();
        byte[] skAsByteArray;
        try {
            skAsByteArray = sKey.getBytes("ASCII");
            skforAES = new SecretKeySpec(skAsByteArray, "AES");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        IV = new IvParameterSpec(iv);
    }

    public String encrypt(byte[] plaintext) {
        byte[] ciphertext = encrypt(CIPHERMODEPADDING, skforAES, IV, plaintext);
        String base64_ciphertext = Base64.encode(ciphertext);
        return base64_ciphertext;
    }

    public String decrypt(String ciphertext_base64) {
        byte[] s = Base64.decode(ciphertext_base64);
        String decrypted = new String(decrypt(CIPHERMODEPADDING, skforAES, IV,
                s));
        return decrypted;
    }

    // Use this method if you want to add the padding manually
    // AES deals with messages in blocks of 16 bytes.
    // This method looks at the length of the message, and adds bytes at the end
    // so that the entire message is a multiple of 16 bytes.
    // the padding is a series of bytes, each set to the total bytes added (a
    // number in range 1..16).
    private byte[] addPadding(byte[] plain) {
        byte plainpad[] = null;
        int shortage = 16 - (plain.length % 16);
        // if already an exact multiple of 16, need to add another block of 16
        // bytes
        if (shortage == 0)
            shortage = 16;
        // reallocate array bigger to be exact multiple, adding shortage bits.
        plainpad = new byte[plain.length + shortage];
        for (int i = 0; i < plain.length; i++) {
            plainpad[i] = plain[i];
        }
        for (int i = plain.length; i < plain.length + shortage; i++) {
            plainpad[i] = (byte) shortage;
        }
        return plainpad;
    }

    // Use this method if you want to remove the padding manually
    // This method removes the padding bytes
    private byte[] dropPadding(byte[] plainpad) {
        byte plain[] = null;
        int drop = plainpad[plainpad.length - 1]; // last byte gives number of
        // bytes to drop

        // reallocate array smaller, dropping the pad bytes.
        plain = new byte[plainpad.length - drop];
        for (int i = 0; i < plain.length; i++) {
            plain[i] = plainpad[i];
            plainpad[i] = 0; // don't keep a copy of the decrypt
        }
        return plain;
    }

    private byte[] encrypt(String cmp, SecretKey sk, IvParameterSpec IV,
                           byte[] msg) {
        try {
            Cipher c = Cipher.getInstance(cmp);
            c.init(Cipher.ENCRYPT_MODE, sk, IV);
            return c.doFinal(msg);
        } catch (NoSuchAlgorithmException nsae) {
            Log.e("AESdemo", "no cipher getinstance support for " + cmp);
        } catch (NoSuchPaddingException nspe) {
            Log.e("AESdemo", "no cipher getinstance support for padding " + cmp);
        } catch (InvalidKeyException e) {
            Log.e("AESdemo", "invalid key exception");
        } catch (InvalidAlgorithmParameterException e) {
            Log.e("AESdemo", "invalid algorithm parameter exception");
        } catch (IllegalBlockSizeException e) {
            Log.e("AESdemo", "illegal block size exception");
        } catch (BadPaddingException e) {
            Log.e("AESdemo", "bad padding exception");
        }
        return null;
    }

    private byte[] decrypt(String cmp, SecretKey sk, IvParameterSpec IV,
                           byte[] ciphertext) {
        try {
            Cipher c = Cipher.getInstance(cmp);
            c.init(Cipher.DECRYPT_MODE, sk, IV);
            return c.doFinal(ciphertext);
        } catch (NoSuchAlgorithmException nsae) {
            Log.e("AESdemo", "no cipher getinstance support for " + cmp);
        } catch (NoSuchPaddingException nspe) {
            Log.e("AESdemo", "no cipher getinstance support for padding " + cmp);
        } catch (InvalidKeyException e) {
            Log.e("AESdemo", "invalid key exception");
        } catch (InvalidAlgorithmParameterException e) {
            Log.e("AESdemo", "invalid algorithm parameter exception");
        } catch (IllegalBlockSizeException e) {
            Log.e("AESdemo", "illegal block size exception");
        } catch (BadPaddingException e) {
            Log.e("AESdemo", "bad padding exception");
            e.printStackTrace();
        }
        return null;
    }
}

Base64：

package com.example.xiaobai.aes;

/**
 * Created by xiaobai on 2017/12/7/007.
 */

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;


public class Base64 {
    private static final char[] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
            .toCharArray();

    public static String encode(byte[] data) {
        int start = 0;
        int len = data.length;
        StringBuffer buf = new StringBuffer(data.length * 3 / 2);

        int end = len - 3;
        int i = start;
        int n = 0;

        while (i <= end) {
            int d = ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 0x0ff) << 8)
                    | (((int) data[i + 2]) & 0x0ff);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append(legalChars[d & 63]);

            i += 3;

            if (n++ >= 14) {
                n = 0;
                buf.append(" ");
            }
        }

        if (i == start + len - 2) {
            int d = ((((int) data[i]) & 0x0ff) << 16)
                    | ((((int) data[i + 1]) & 255) << 8);

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append(legalChars[(d >> 6) & 63]);
            buf.append("=");
        } else if (i == start + len - 1) {
            int d = (((int) data[i]) & 0x0ff) << 16;

            buf.append(legalChars[(d >> 18) & 63]);
            buf.append(legalChars[(d >> 12) & 63]);
            buf.append("==");
        }

        return buf.toString();
    }

    private static int decode(char c) {
        if (c >= 'A' && c <= 'Z')
            return ((int) c) - 65;
        else if (c >= 'a' && c <= 'z')
            return ((int) c) - 97 + 26;
        else if (c >= '0' && c <= '9')
            return ((int) c) - 48 + 26 + 26;
        else
            switch (c) {
                case '+':
                    return 62;
                case '/':
                    return 63;
                case '=':
                    return 0;
                default:
                    throw new RuntimeException("unexpected code: " + c);
            }
    }

    /**
     * Decodes the given Base64 encoded String to a new byte array. The byte
     * array holding the decoded data is returned.
     */

    public static byte[] decode(String s) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        try {
            decode(s, bos);
        } catch (IOException e) {
            throw new RuntimeException();
        }
        byte[] decodedBytes = bos.toByteArray();
        try {
            bos.close();
            bos = null;
        } catch (IOException ex) {
            System.err.println("Error while decoding BASE64: " + ex.toString());
        }
        return decodedBytes;
    }

    private static void decode(String s, OutputStream os) throws IOException {
        int i = 0;

        int len = s.length();

        while (true) {
            while (i < len && s.charAt(i) <= ' ')
                i++;

            if (i == len)
                break;

            int tri = (decode(s.charAt(i)) << 18)
                    + (decode(s.charAt(i + 1)) << 12)
                    + (decode(s.charAt(i + 2)) << 6)
                    + (decode(s.charAt(i + 3)));

            os.write((tri >> 16) & 255);
            if (s.charAt(i + 2) == '=')
                break;
            os.write((tri >> 8) & 255);
            if (s.charAt(i + 3) == '=')
                break;
            os.write(tri & 255);

            i += 4;
        }
    }
}

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        String input = "hello AES!";
        byte[] mBytes = null;
        AES mAes = new AES();
        try {
            mBytes = input.getBytes("UTF8");
            String enString = mAes.encrypt(mBytes);
            Log.i("AES encode text is ", enString);
            String deString = mAes.decrypt(enString);
            Log.i("AES decode text is ", deString);
        } catch (Exception e) {

        }
    }

}

12-07 16:27:35.826 23284-23284/com.example.xiaobai.aes I/AES encode text is: 7P9hogAc+Mn0QKyGRCRA9w==
12-07 16:27:35.827 23284-23284/com.example.xiaobai.aes I/AES decode text is: hello AES!