SharedPreferences是Android提供用来存储一些简单配置信息的机制，其以KEY-VALUE对的方式进行存储，以便我们可以方便进行读取和存储。主要可以用来存储应用程序常量参数或登录账号用户名密码等。
如果我们不希望存在SharedPreferences中的数据被外界读取，可以使用AES加密算法对内容进行加密。
AES加密：密码学中的高级加密标准（Advanced Encryption Standard，AES），又称高级加密标准Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。该算法为比利时密码学家Joan Daemen和Vincent Rijmen所设计，结合两位作者的名字，以Rijndael之命名之。

1. 创建AES加解密工具类AESEncryptor.java
其中主要提供加密encrypt、解密decrypt两个方法。
以下为该类文件的源码：

/** * AES加密器 * @author Eric_Ni * */  
public class AESEncryptor {
    /** * AES加密密钥 */ 
    public static String AESkey = "0123456789012345";
    /** * AES加密 */  
    public static String encrypt(String seed, String cleartext) throws Exception {    
        byte[] rawKey = getRawKey(seed.getBytes());    
        byte[] result = encrypt(rawKey, cleartext.getBytes());    
        return toHex(result);    
    }    

    /** * AES解密 */  
    public static String decrypt(String seed, String encrypted) throws Exception {    
        byte[] rawKey = getRawKey(seed.getBytes());    
        byte[] enc = toByte(encrypted);    
        byte[] result = decrypt(rawKey, enc);    
        return new String(result);    
    }    

    private static byte[] getRawKey(byte[] seed) throws Exception {    
       KeyGenerator kgen = KeyGenerator.getInstance("AES");
       // SHA1PRNG 强随机种子算法, 要区别4.2以上版本的调用方法 
       SecureRandom sr = null;  
       if (android.os.Build.VERSION.SDK_INT >=  17) {  
         sr = SecureRandom.getInstance("SHA1PRNG", "Crypto");  
       } else {  
         sr = SecureRandom.getInstance("SHA1PRNG");  
       }  
        sr.setSeed(seed);    
        kgen.init(128, sr); // 192 and 256 bits may not be available 
        SecretKey skey = kgen.generateKey();    
        byte[] raw = skey.getEncoded();    
        return raw;    
    }    


    private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {    
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
        Cipher cipher = Cipher.getInstance("AES");    
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);    
        byte[] encrypted = cipher.doFinal(clear);    
        return encrypted;    
    }    

    private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {    
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");    
        Cipher cipher = Cipher.getInstance("AES");    
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);    
        byte[] decrypted = cipher.doFinal(encrypted);    
        return decrypted;    
    }    

    public static String toHex(String txt) {    
        return toHex(txt.getBytes());    
    }    
    public static String fromHex(String hex) {    
        return new String(toByte(hex));    
    }    

    public static byte[] toByte(String hexString) {    
        int len = hexString.length()/2;    
        byte[] result = new byte[len];    
        for (int i = 0; i < len; i++)    
            result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();    
        return result;    
    }    

    public static String toHex(byte[] buf) {    
        if (buf == null)    
            return "";    
        StringBuffer result = new StringBuffer(2*buf.length);    
        for (int i = 0; i < buf.length; i++) {    
            appendHex(result, buf[i]);    
        }    
        return result.toString();    
    }    
    private final static String HEX = "0123456789ABCDEF";    
    private static void appendHex(StringBuffer sb, byte b) {    
        sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));    
    }    
}  

2. 使用工具类

存储：

    public void store(Context context, String text) {
        String afterAESEncrypt = "";
        SharedPreferences mSharedPreferences= context.getSharedPreferences("NodeListOrder", context.MODE_PRIVATE);
        SharedPreferences.Editor editor = mSharedPreferences.edit();
        try{  
            afterAESEncrypt = AESEncryptor.encrypt(AESEncryptor.AESkey, nodeString);
        }catch(Exception ex){}
        editor.putString("nodeString", afterAESEncrypt);
        editor.commit();
    }

读取：

public String read (Context context) {
        String afterAESdecrypt = "";
        SharedPreferences mSharedPreferences= context.getSharedPreferences("NodeListOrder", context.MODE_PRIVATE);
        String text= mSharedPreferences.getString("nodeString", "null");
        try{  
            afterAESdecrypt  = AESEncryptor.decrypt(AESEncryptor.AESkey, text);  
            }catch(Exception ex){}      
        return afterAESdecrypt;
    }

注意：在安卓4.2及以上解密时会报Exception：
javax.crypto.BadPaddingException: pad block corrupted
所以需要修改SHA1PRNG 强随机种子算法，
sr = SecureRandom.getInstance(“SHA1PRNG”, “Crypto”);