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;
    }
    
}