java 加密解密 示例

import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.ObjectInputStream; 
import java.io.ObjectOutputStream; 
import java.security.Key; 
import java.security.MessageDigest; 
 
import javax.crypto.Cipher; 
import javax.crypto.KeyGenerator; 
 
public class Demo { 
    public static void main(String args[]) { 
        String password = "administrator"; 
        try { 
            Demo.PrivEncrypt(password,"t.obj"); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
 
    /**
     * 
     * @param oldStr
     *            要加密的串
     * @param keyFile
     *            私有key所在的文件路径
     * @throws Exception
     */ 
    public static void PrivEncrypt(String oldStr,String keyFile) throws Exception { 
        System.out.println("原始："+oldStr); 
        byte[] plainText = oldStr.getBytes("GBK"); 
        Key key = getPriveKey(keyFile); 
        // 获得一个私鈅加密类Cipher，ECB是加密方式，PKCS5Padding是填充方法 
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding"); 
         
        cipher.init(Cipher.ENCRYPT_MODE, key);// 使用私鈅加密 
        byte[] cipherText = cipher.doFinal(plainText); 
        System.out.println("加密："+new String(cipherText, "UTF8")); 
         
        cipher.init(Cipher.DECRYPT_MODE, key);// 使用私钥解密 
        byte[] newPlainText = cipher.doFinal(cipherText); 
        System.out.println("解密："+new String(newPlainText, "UTF8")); 
    } 
 
    // 把Key 写到文件中：生成一个私有Key对象，保存在文件中 
    public static void setPriveKey(String file) { 
        FileOutputStream fos; 
        try { 
            fos = new FileOutputStream(file); 
            KeyGenerator keyGen = KeyGenerator.getInstance("DES"); 
            keyGen.init(128); 
            Key key = keyGen.generateKey();// 生成私钥Key 
            ObjectOutputStream oos = new ObjectOutputStream(fos); 
            oos.writeObject(key); 
            oos.close(); 
        } catch (Exception e1) { 
            e1.printStackTrace(); 
        } 
    } 
    // 从文件中读Key：客户端可以根据管理员提供的私钥Key文件提取Key对象 
    public static Key getPriveKey(String file) throws Exception { 
        FileInputStream fis = new FileInputStream(file); 
        ObjectInputStream ois = new ObjectInputStream(fis); 
        Key key = (Key) ois.readObject(); 
        return key; 
    } 
} 
/* 运行结果：
* 原始：administrator 
* 加密：!Y????I?? ??R;?
* 解密：administrator
*/