问题描述
我有一个想要写入HttpServletResponse的InputStream。
有这种方法,由于使用了byte []
I have an InputStream that I want written to a HttpServletResponse.There's this approach, which takes too long due to the use of byte[]
InputStream is = getInputStream();
int contentLength = getContentLength();
byte[] data = new byte[contentLength];
is.read(data);
//response here is the HttpServletResponse object
response.setContentLength(contentLength);
response.write(data);
我想知道在速度和效率方面最好的方法是什么。
I was wondering what could possibly be the best way to do it, in terms of speed and efficiency.
推荐答案
只需先写入块而不是将其完全复制到Java的内存中。以下基本示例将其写入10KB的块中。这样,您最终只能获得10KB的内存使用量,而不是完整的内容长度。此外,最终用户将更快地开始获取部分内容。
Just write in blocks instead of copying it entirely into Java's memory first. The below basic example writes it in blocks of 10KB. This way you end up with a consistent memory usage of only 10KB instead of the complete content length. Also the enduser will start getting parts of the content much sooner.
response.setContentLength(getContentLength());
byte[] buffer = new byte[10240];
try (
InputStream input = getInputStream();
OutputStream output = response.getOutputStream();
) {
for (int length = 0; (length = input.read(buffer)) > 0;) {
output.write(buffer, 0, length);
}
}
作为creme de la creme的性能,你可以使用NIO 和直接分配。在某个自定义实用程序类中创建以下实用程序/帮助程序方法,例如 Utils
:
public static long stream(InputStream input, OutputStream output) throws IOException {
try (
ReadableByteChannel inputChannel = Channels.newChannel(input);
WritableByteChannel outputChannel = Channels.newChannel(output);
) {
ByteBuffer buffer = ByteBuffer.allocateDirect(10240);
long size = 0;
while (inputChannel.read(buffer) != -1) {
buffer.flip();
size += outputChannel.write(buffer);
buffer.clear();
}
return size;
}
}
然后使用以下内容:
response.setContentLength(getContentLength());
Utils.stream(getInputStream(), response.getOutputStream());
这篇关于将InputStream写入HttpServletResponse的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!