java怎么给文件加密

  // 第一步文件的加密
        // 先用字节缓冲流读取文件
        BufferedInputStream bis = new BufferedInputStream(new FileInputStream(“你要加密的文件全路径”));
        // 再用字节数组输出流将文件写到一个字节数组内
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        调用writeFile2方法写到一个字节数组内
        writeFile2(baos, bis)
        // 将字节数组输出流内的内容转换成一个字节数组
        byte[] byteArray = baos.toByteArray();

writeFile2方法：
/**

    private static void writeFile2(ByteArrayOutputStream baos, BufferedInputStream bis) throws Exception {
        byte []  bytes = new byte [1024]; 
        int len = -1;
        while ((len= bis.read(bytes))!=-1) {
            baos.write(bytes, 0, len);
        }
        bis.close();
    }

private static byte[] jiami(byte[] byteArray) {
        for (int i = 0; i < byteArray.length; i++) {
            byteArray[i] = (byte) (byteArray[i] ^ 96);// 将异或后的数据强转成字节类型
        }
        return byteArray;
    }

int size = byteArray.length / 3;
        byte[] byteArray1 = new byte[size];
        byte[] byteArray2 = new byte[size];
        byte[] byteArray3 = new byte[byteArray.length-2*size];
        for (int i = 0; i < size; i++) {
            byteArray1[i] = byteArray[i];
        }
        for (int i = size; i < 2*size; i++) {
            byteArray2[i - size] = byteArray[i];
        }
        for (int i = size * 2; i < byteArray.length; i++) {
            byteArray3[i - size * 2] = byteArray[i];
        }

ByteArrayInputStream bais = null;
        BufferedOutputStream bos = null;
        for (int i = 0; i < 3; i++) {
            switch (i) {
            case 0:// 第一份
                bais = new ByteArrayInputStream(byteArray1);
                // 用字节缓冲输出流将数组内容写到具体的位置
                bos = new BufferedOutputStream(new FileOutputStream("F:/test/111.dll"));
                // 下面还要用到这个方法写数据的方法，可以定义一个方法
                writeFile(size, bais, bos, 0);
                break;
            case 1:// 第二份
                bais = new ByteArrayInputStream(byteArray2);
                // 用字节缓冲输出流将数组内容写到具体的位置
                bos = new BufferedOutputStream(new FileOutputStream("F:/test/112.dll"));
                writeFile(size, bais, bos, 1);
                break;
            case 2:// 第三份
                bais = new ByteArrayInputStream(byteArray3);
                bos = new BufferedOutputStream(new FileOutputStream("F:/test/113.dll"));
                writeFile(byteArray.length-2*size, bais, bos, 2);
                break;
            }
        }

writeFile方法
     private static void writeFile(int size, ByteArrayInputStream bais, BufferedOutputStream bos, int i)
            throws Exception {

        byte[] bytes = new byte[1024];
        int len = -1;
        while ((len = bais.read(bytes)) != -1) {
            bos.write(bytes, 0, len);
        }
        bos.close();
    }