[英]Java: Write to OutputStream and then use it as InputStream
I want to get a file from a remote storage as an InputStream without saving it to the local File System. 我想从远程存储中获取一个文件作为InputStream而不将其保存到本地文件系统。 The remote storage provides a Java API with a method that takes an OutputStream and dumps the file data into it. 远程存储为Java API提供了一种方法,该方法接受OutputStream并将文件数据转储到其中。
void dump(OutputStream dest);
The easy way I've come up with is to create a temporary file, dump the data into it and reopen it as an InputStream. 我想出的简单方法是创建一个临时文件,将数据转储到其中并重新打开它作为InputStream。 But this approach creates a temporary file. 但是这种方法会创建一个临时文件。 Is there an easy way to achieve the same result without a proxy file? 有没有代理文件可以轻松实现相同的结果?
Two options: 两种选择:
If the "file" in question is small enough for it to be viable, you could read the data into a ByteArrayOutputStream
, and then use its toByteArray
method to construct a ByteArrayInputStream
to read from. 如果所讨论的“文件”足够小以使其可行,则可以将数据读入ByteArrayOutputStream
,然后使用其toByteArray
方法构造要读取的ByteArrayInputStream
。
To avoid storing more in memory than necessary, you could use PipedOutputStream
and PipedInputStream
. 为避免在内存中存储超过必要的内容,可以使用PipedOutputStream
和PipedInputStream
。
PipedOutputStream
: PipedOutputStream
:
A piped output stream can be connected to a piped input stream to create a communications pipe. 管道输出流可以连接到管道输入流以创建通信管道。 The piped output stream is the sending end of the pipe. 管道输出流是管道的发送端。 Typically, data is written to a
PipedOutputStream
object by one thread and data is read from the connectedPipedInputStream
by some other thread. 通常,数据由一个线程写入PipedOutputStream
对象,而某些其他线程从连接的PipedInputStream
读取数据。
PipedInputStream
: PipedInputStream
:
A piped input stream should be connected to a piped output stream; 管道输入流应连接到管道输出流; the piped input stream then provides whatever data bytes are written to the piped output stream. 然后,管道输入流提供写入管道输出流的任何数据字节。 Typically, data is read from a PipedInputStream object by one thread and data is written to the corresponding PipedOutputStream by some other thread. 通常,一个线程从PipedInputStream对象读取数据,并且某些其他线程将数据写入相应的PipedOutputStream。
You give the API the output stream, and read from the input stream. 您为API提供输出流,并从输入流中读取。
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