Byte []到InputStream或OutputStream [英] Byte[] to InputStream or OutputStream

问题描述

我的数据库表中有一个blob列，我必须在我的Java程序中使用 byte [] 作为映射并使用我必须使用的数据将其转换为 InputStream 或 OutputStream 。但是当我这样做时，我不知道内部会发生什么。我可以简单地向我解释当我进行此转换时发生了什么吗？

I have a blob column in my database table, for which I have to use byte[] in my Java program as a mapping and to use this data I have to convert it to InputStream or OutputStream. But I don't know what happens internally when I do so. Can anyone briefly explain me what's happening when I do this conversion?

推荐答案

您创建并使用字节数组I / O流如下：

You create and use byte array I/O streams as follows:

byte[] source = ...;
ByteArrayInputStream bis = new ByteArrayInputStream(source);
// read bytes from bis ...

ByteArrayOutputStream bos = new ByteArrayOutputStream();
// write bytes to bos ...
byte[] sink = bos.toByteArray();

假设您使用的JDBC驱动程序实现了标准 JDBC Blob界面（不是全部都有），你可以也使用 getBinaryStream InputStream 或 OutputStream 连接到blob >和 setBinaryStream 方法 ¹ ，你也可以直接获取和设置字节。

Assuming that you are using a JDBC driver that implements the standard JDBC Blob interface (not all do), you can also connect a InputStream or OutputStream to a blob using the getBinaryStream and setBinaryStream methods¹, and you can also get and set the bytes directly.

（通常，您应该采取适当的步骤来处理任何异常，并关闭流。但是，关闭 bis 和 bos 在上面的示例中是不必要的，因为它们不与任何外部资源相关联;例如文件描述符，套接字，数据库连接。）

(In general, you should take appropriate steps to handle any exceptions, and close streams. However, closing bis and bos in the example above is unnecessary, since they aren't associated with any external resources; e.g. file descriptors, sockets, database connections.)

^{1 - setBinaryStream 方法实际上是一个getter。去图。}

^{1 - The setBinaryStream method is really a getter. Go figure.}

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