Android开发中如何保存用户名密码在本地

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Android开发中用户登录后用户名密码需要保存到本地，方便下次免登陆打开APP。但密码肯定不能直接明文保存，所以需要简单加密，下面分享几个函数，方便给密码加解密，可随意设置加密使用的key，操作简单。

代码分享如下：

import java.security.Key;import javax.crypto.Cipher;import javax.crypto.spec.SecretKeySpec;/** * Date: 2016/2/19 10:22 * * @author hornsey */public class DES {    /**     * 获取加密密钥Key     * @param keyString     * @return     */    public static Key getKey(String keyString) {        byte[] keyStringByte = keyString.getBytes();        byte[] keyByte = new byte[8];        for(int i = 0; i<keyStringByte.length && i < keyByte.length; i++) {            keyByte[i] = keyStringByte[i];        }        Key key = new SecretKeySpec(keyByte,"DES");        return key;    }    /**     * 将byte数组转换成16进制String     * @param bytes     * @return     * @throws Exception     */    public static String byteArr2HexStr(byte[] bytes) throws Exception {        StringBuffer sb = new StringBuffer(bytes.length*2);        for(int i = 0; i < bytes.length; i++){            if((bytes[i] & 0xFF) < 0x10)                sb.append("0");            sb.append(Integer.toHexString(bytes[i]&0xFF));        }        return sb.toString();    }    /**     * 将16进制string转换成byte数组     * @param str     * @return     * @throws Exception     */    public static byte[] hexStr2ByteArr(String str) throws Exception {        byte[] bytes = str.getBytes();        int len = bytes.length;        byte[] arr = new byte[len/2];        for(int i = 0; i < len; i=i+2) {            String tmp = new String(bytes,i,2);            arr[i/2] = (byte) Integer.parseInt(tmp,16);        }        return arr;    }    /**     * 对字符串进行DES加密     * @param val 原始字符串     * @param key 加密使用的key     * @return     * @throws Exception     */    public static String getDES(String val, String key) throws Exception {        if(val == null || key == null)            return null;        Cipher encryptCipher = Cipher.getInstance("DES");        encryptCipher.init(Cipher.ENCRYPT_MODE,getKey(key));        byte[] cipherByte = encryptCipher.doFinal(val.getBytes());        return byteArr2HexStr(cipherByte);    }    /**     * 对DES加密后的16进制字符串进行解密     * @param val     * @param key     * @return     * @throws Exception     */    public static String getDESOri(String val, String key) throws Exception {        if(val == null || key == null)            return null;        Cipher decryptCipher = Cipher.getInstance("DES");        decryptCipher.init(Cipher.DECRYPT_MODE,getKey(key));        byte[] originalByte = decryptCipher.doFinal(hexStr2ByteArr(val));        return new String(originalByte);    }    public static void main(String[] args) throws Exception{        String s = "Hello,World!";        String b = getDES(s,"hello");        System.out.println("DES(" + s +") = " + b);        System.out.println("original(" + b +") = " + getDESOri(b,"hello"));    }}

运行后结果如下：

DES(Hello,World!) = 1022707424afc28b80b9878d1fbdecf2
original(1022707424afc28b80b9878d1fbdecf2) = Hello,World!

参考文章：http://lichune88.blog.163.com/blog/static/63027068201102114153360/

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