字节流InputStream与OutputStream

public static void main(String[] args) {
    ByteStream byteStream = new ByteStream();
    //1、字节输入流，表示把文件写入到硬盘中
    byteStream.outPutStream("D:\2.txt");
    //2、字节输出流，表示想硬盘读出文件显示出来
    byteStream.inputStream("D:\2.txt");
}


    private void inputStream(String path) {
        File file = new File(path);
        if (!file.exists()) {
            IAssert.throwMsg("文件不存在：" + path);
        }

        //todo 下面两行都可以实现字节流读取
        InputStream fileInputStream = null;
        try {
            fileInputStream = new FileInputStream(file);
        } catch (FileNotFoundException e) {
            IAssert.throwMsg("文件不存在：" + path);
        }

        try {
                byte[] bytes = new byte[1024];
//        byte[] bytes = new byte[(int) file.length()];

                int len = fileInputStream.read(bytes);
                while (len != -1) {
                    len = fileInputStream.read(bytes);
                }
                String currentData = new String(bytes, StandardCharsets.UTF_8);
            IAssert.throwMsg("读出的数据为：" + currentData);
            //必须手动关闭，因为fileInputStream不属于内存的资源，导致垃圾回收器无法回收这些不用的资源。
            fileInputStream.close();
        } catch (IOException e) {
            IAssert.throwMsg("写入失败");
        }
    }

    //读取文件中所有的内容
    private void inputStreamAll(String path) {
        File file = new File(path);
        if (!file.exists()) {
            IAssert.throwMsg("文件不存在：" + path);
        }

        StringBuffer buffer = new StringBuffer();
        //todo 下面两行都可以实现字节流读取
        long length = (file.length()/1024)+1;
        IAssert.throwMsg("长度为："+length);
        InputStream fileInputStream = null;
        try {
            fileInputStream = new FileInputStream(file);
        } catch (FileNotFoundException e) {
            IAssert.throwMsg("文件不存在：" + path);
        }

        try {
            for (int i = 0; i < length; i++) {
                byte[] bytes = new byte[1024];
//        byte[] bytes = new byte[(int) file.length()];

                int len = fileInputStream.read(bytes);
                while (len != -1) {
                    len = fileInputStream.read(bytes);
                }
                String currentData = new String(bytes, StandardCharsets.UTF_8);
                buffer.append(currentData);
            }
            IAssert.throwMsg("读出的数据为：" + buffer.toString());
            //必须手动关闭，因为fileInputStream不属于内存的资源，导致垃圾回收器无法回收这些不用的资源。
            fileInputStream.close();
        } catch (IOException e) {
            IAssert.throwMsg("写入失败");
        }
    }

    private void outPutStream(String path) {
        File file = new File(path);
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                IAssert.throwMsg("创建文件失败：" + path);
            }
        }

        String content = "我是中国人";
        FileOutputStream fileOutputStream = null;
        try {
            fileOutputStream = new FileOutputStream(file);
        } catch (FileNotFoundException e) {
            IAssert.throwMsg("找不到文件：" + file.getPath());
        }
        try {
            fileOutputStream.write(content.getBytes(StandardCharsets.UTF_8));
            fileOutputStream.close();
        } catch (IOException e) {
            IAssert.throwMsg("写入失败");
        }
    }