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确定 InputStream 的大小

[英]Determine the size of an InputStream

 原文  2009-07-13 13:05:33  5   13    java/ arrays/ size/ inputstream

问题描述

My current situation is: I have to read a file and put the contents into InputStream .我目前的情况是：我必须读取一个文件并将内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .之后，我需要将InputStream的内容放入一个字节数组中，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上传的文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，它类似于FileItemFactory ，而ServletFileUpload来自 Apache Commons FileUpload 包。

13 个解决方案

解决方案1
 64  2013-08-14 16:30:07

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案2
 37  2009-07-13 13:10:13

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案3
 21  2009-07-13 13:09:11

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案4
 16 已采纳  2009-07-13 13:12:19

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案5
 8  2018-11-23 13:59:55

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案6
 4  2013-03-21 12:11:56

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案7
 2  2021-03-02 04:47:12

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案8
 1  2017-09-22 10:05:25

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案9
 0  2019-04-10 18:24:58

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案10
 0  2021-12-12 19:32:45

If you need to stream the data to another object that doesn't allow you to directly determine the size (eg javax.imageio.ImageIO ), then you can wrap your InputStream within a CountingInputStream (Apache Commons IO), and then read the size:如果您需要将数据流式传输到另一个不允许您直接确定大小的对象（例如javax.imageio.ImageIO ），那么您可以将您的InputStream包装在一个CountingInputStream （Apache Commons IO）中，然后读取大小：

CountingInputStream countingInputStream = new CountingInputStream(inputStream);
// ... process the whole stream ...
int size = countingInputStream.getCount();

解决方案11
 0  2022-07-11 14:47:25

Add to your pom.xml:添加到您的 pom.xml：

  <dependency>
    <groupId>commons-io</groupId>
    <artifactId>commons-io</artifactId>
    <version>2.5</version>
  </dependency>

Use to get the content type lenght (InputStream file):用于获取内容类型长度（InputStream 文件）：

IOUtils.toByteArray(file).length

解决方案12
 -1  2015-11-10 23:17:04

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

解决方案13
 -1  2017-12-05 15:56:05

My current situation is: I have to read a file and put the contents into InputStream .我当前的情况是：我必须读取一个文件并将其内容放入InputStream 。 Afterwards I need to place the contents of the InputStream into a byte array which requires (as far as I know) the size of the InputStream .然后，我需要将InputStream的内容放入一个字节数组，该数组需要（据我所知） InputStream的大小。 Any ideas?有任何想法吗？

As requested, I will show the input stream that I am creating from an uploaded file根据要求，我将显示我从上载文件创建的输入流

InputStream uploadedStream = null;
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
java.util.List items = upload.parseRequest(request);      
java.util.Iterator iter = items.iterator();

while (iter.hasNext()) {
    FileItem item = (FileItem) iter.next();
    if (!item.isFormField()) {
        uploadedStream = item.getInputStream();
        //CHANGE uploadedStreambyte = item.get()
    }
}

The request is a HttpServletRequest object, which is like the FileItemFactory and ServletFileUpload is from the Apache Commons FileUpload package.该请求是一个HttpServletRequest对象，类似于FileItemFactory而ServletFileUpload来自Apache Commons FileUpload包。

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