Java复制部分InputStream到OutputStream [英] Java copy part of InputStream to OutputStream

问题描述

我有一个文件3236000字节，我想从开始读取2936000，并写入OutputStream

  InputStream is = new FileInputStream（file1）; 
 OutputStream os = new FileOutputStream（file2）; 
 
 AFunctionToCopy（is，os，0,2936000）; / *一个函数或源代码写入输入流0to2936000字节* / 
  

我可以读写byte字节，但它是缓慢的（我认为）从缓冲的读取
我如何复制呢？

解决方案

  public static void copyStream（InputStream input，OutputStream output，long start，long end）
 throws IOException 
 {
 for（int i = 0; i  byte [] buffer = new byte [1024]; // Adjust if you want 
 int bytesRead; 
 while（（bytesRead = input.read（buffer））！= -1&& amp; amp;& amp; amp; amp; R< = end）//测试EOF或结束
 {
 output.write buffer，0，bytesRead）; 
} 
} 
  

$ b

I have a file with 3236000 bytes and I want to read 2936000 from start and write to an OutputStream

InputStream is = new FileInputStream(file1);
OutputStream os = new FileOutputStream(file2);

AFunctionToCopy(is,os,0,2936000); /* a function or sourcecode to write input stream 0to2936000 bytes */

I can read and write byte by byte, but it's to slow (i think) from buffered reading How can do I copy it?

解决方案

public static void copyStream(InputStream input, OutputStream output, long start, long end)
    throws IOException
{
    for(int i = 0; i<start;i++) input.read(); // dispose of the unwanted bytes
    byte[] buffer = new byte[1024]; // Adjust if you want
    int bytesRead;
    while ((bytesRead = input.read(buffer)) != -1 && bytesRead<=end) // test for EOF or end reached
    {
        output.write(buffer, 0, bytesRead);
    }
}

should work for you.

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