缓冲流练习1

练习

实现图片加密操作。
提示

int b = 0;
while((b = fis.read()) != -1){
    fos.write(b^5);
}

//图片的加密
    @Test
    public void test1(){
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            fis = new FileInputStream("爱情与友情.jpg");
            fos = new FileOutputStream("爱情与友情secret.jpg");

            byte[] buffer = new byte[20];
            int len;
            while((len = fis.read(buffer)) != -1){
                //字节数组进行修改
                //错误的
    //            for(byte b: buffer){
    //                b = (byte) (b^5);
    //            }

                //正确的
                for (int i = 0; i < len; i++) {
                    buffer[i] = (byte) (buffer[i]^5);
                }

                fos.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fis != null){
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            if (fos != null){
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }