Java 非对称加密

 package test;

 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.security.Key;
 import java.security.KeyPair;
 import java.security.KeyPairGenerator;

 import javax.crypto.Cipher;

 public class testcase {

     public static void main(String[] args) throws Exception {
         PublicEnrypt();
         privateDecrypt();

     }
     //加密
     public static void PublicEnrypt() throws Exception{
         // 实例化加密工具，使用RSA算法
         Cipher cipher=Cipher.getInstance("RSA");
         // 实例化Key
         KeyPairGenerator keypairGenerator=KeyPairGenerator.getInstance("RSA");
         // 获得一对钥匙
         KeyPair keyPair=keypairGenerator.generateKeyPair();
         // 获取公钥
         Key publicKey=keyPair.getPublic();
         // 获取私钥
         Key privateKey=keyPair.getPrivate();
         // 用公钥加密
         cipher.init(Cipher.ENCRYPT_MODE, publicKey);
         byte []result =cipher.doFinal("数据内容".getBytes("UTF-8"));
         // 将私钥写入文件
         saveKey(privateKey,"zxx_private.key");
         // 加密后的数据存储
         saveData(result,"public_encryt.dat");
         System.out.println(new String(result,"UTF-8"));
     }
     //解密
     public static void privateDecrypt() throws Exception{
         //实例化加密工具
         Cipher cipher=Cipher.getInstance("RSA");
         // 获取私钥
         Key privateKey=readKey("zxx_private.key");
         // 获取加密后的信息
         byte[] src=readData("public_encryt.dat");
         // 用私钥解密
         cipher.init(Cipher.DECRYPT_MODE, privateKey);
         byte[] result=cipher.doFinal(src);
         System.out.println(new String(result,"UTF-8"));
     }
     // 保存数据
     public static void saveData(byte[] result,String fileName) throws Exception{
         FileOutputStream fosData=new FileOutputStream(fileName);
         fosData.write(result);
         fosData.close();
     }
     // 保存密钥
     public static void saveKey(Key key,String fileName) throws Exception{
         FileOutputStream fosKey=new FileOutputStream(fileName);
         ObjectOutputStream oosSecretKey=new ObjectOutputStream(fosKey);
         oosSecretKey.writeObject(key);
         oosSecretKey.close();
         fosKey.close();
     }
       //读取密钥
     public static Key readKey(String fileName) throws Exception{
         FileInputStream fisKey=new FileInputStream(fileName);
         ObjectInputStream oisKey=new ObjectInputStream(fisKey);
         Key key=(Key)oisKey.readObject();
         oisKey.close();
         fisKey.close();
         return key;
     }
        // 读取数据
     public static byte[] readData(String fileName) throws Exception{
         FileInputStream fisDat=new FileInputStream(fileName);
         byte[] src=new byte[fisDat.available()];
         int len=fisDat.read(src);
         int total=0;
         while(total<src.length){
             total+=len;
             len=fisDat.read(src, total, src.length-total);
         }
         fisDat.close();
          return src;
     }

 }