Java-io Xiao Kee

Ashamed to say, work for more than a year, the IO is still not very understanding. Not only IO, but also network, and multi-threading. shame!!!

The following days, the first to engage in multi-threading, and then engage in IO, and then network, six months must be completed!

Well, today I finally understand the difference between the three write of OutputStream, here's a little bit to remember

1. Instructions in the documentation

write(byte[] b)
Writes b.length bytes from the specified byte array to this file output stream.

write(byte[] b, int off, int len)
Writes len bytes from the specified byte array starting at offset to this off file output stream.

write(int b)
Writes the specified byte to this file output stream.

2. Understanding

①write (byte[] b) writes B.length bytes each time, even if the last byte array is not full, it will write B.lenth bytes.

eg

FileInputStream in =NewFileInputStream (NewFile ("C:/users/admin/desktop/js/node.txt")); byteB[] =New byte[50]; FileOutputStream out=NewFileOutputStream (NewFile ("C:/users/admin/desktop/js/node1.txt")); intLen = 0; System.out.println ("Total Length" +in.available ());  while(len = In.read (b))!=-1) {System.out.println (len);        Out.write (b);        } in.close ();        Out.flush (); Out.close ();

Original file contents

Write the file

Console output

As can be seen, because the last read of the byte actually only 4, but the output of the file is a lot more (46 bytes should), it seems that the last read of the content was written to the

So, even if the last byte array is not full, it will write B.lenth bytes

② write(byte[] b, int off, int len)

Off, half is 0.

Len is the number of bytes to write this time.

Change the code above to

FileInputStream in =NewFileInputStream (NewFile ("C:/users/admin/desktop/js/node.txt")); byteB[] =New byte[50]; FileOutputStream out=NewFileOutputStream (NewFile ("C:/users/admin/desktop/js/node1.txt")); intLen = 0; System.out.println ("Total Length" +in.available ());  while(len = In.read (b))!=-1) {System.out.println (len); Out.write (b,0, Len);        } in.close ();        Out.flush (); Out.close ();

The difference lies in the Out.write method

In this case, the written file is no problem, the last time to read 4 bytes, write 4 bytes.

③write (int b)

Writes the specified byte to this output stream. The general contract-is-one byte is written to the write output stream. The byte to being written is the eight low-order bits of the argument b . The High-order bits of is b ignored.

Don't know ...

Java-io Xiao Kee