[英]What is the best way to transfer a file using Java?
I am writing code for uploading a file from a client to my server and the performance isn't as fast as I think it should be. 我正在编写用于将文件从客户端上传到我的服务器的代码,性能没有我想象的那么快。
I have the current code snippet that is doing the file transfer and I was wondering how I could speed up the transfer. 我有正在进行文件传输的当前代码片段,我想知道如何加快传输速度。
Sorry about all of the code: 抱歉,所有代码:
InputStream fileItemInputStream ;
OutputStream saveFileStream;
int[] buffer;
while (fileItemInputStream.available() > 0) {
buffer = Util.getBytesFromStream(fileItemInputStream);
Util.writeIntArrToStream(saveFileStream, buffer);
}
saveFileStream.close();
fileItemInputStream.close();
The Util methods are as follows: Util方法如下:
public static int[] getBytesFromStream(InputStream in, int size) throws IOException {
int[] b = new int[size];
int count = 0;
while (count < size) {
b[count++] = in.read();
}
return b;
}
and: 和:
public static void writeIntArrToStream(OutputStream out, int[] arrToWrite) throws IOException {
for (int i = 0; i < arrToWrite.length; i++) {
out.write(arrToWrite[i]);
}
}
Reading a single byte at a time will be horribly inefficient. 一次读取一个字节将是非常低效的。 You're also relying on
available
, which is rarely a good idea. 你也依赖于
available
,这很少是一个好主意。 (It will return 0 if there are no bytes currently available, but there may be more to come.) (如果当前没有可用的字节,它将返回0,但可能还会有更多字节。)
This is the right sort of code to copy a stream: 这是复制流的正确代码:
public void copyStream(InputStream input, OutputStream output) throws IOException
{
byte[] buffer = new byte[32*1024];
int bytesRead;
while ((bytesRead = input.read(buffer, 0, buffer.length)) > 0)
{
output.write(buffer, 0, bytesRead);
}
}
(The caller should close both streams.) (调用者应关闭两个流。)
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