Java-io Stream Randomaccessfile Class

• Randomaccessfile

1. Java provides access to the contents of a file that can read files or write files.
2. Support random access to files, can access any location of the file.
3. Java file model, the file on the hard disk is a byte byte stored in Byte, is a collection of data
4. Open file, there are two modes, "RW" read-write, "R" read-only, Randomaccessfile RAF = new Randomaccessfile (file, "RW");, file pointer, open the file pointer at the beginning point = 0;
5. Write method, Raf.write ()-Write only one byte (last eight bits), and the pointer points to the next position, ready to write again
6. Read method, int b = Raf.read () and read a byte
7. The file must be closed after reading and writing (Oracle official note)

Rafdemo.java

 PackageCom.test.io;ImportJava.io.File;Importjava.io.IOException;ImportJava.io.RandomAccessFile;Importjava.util.Arrays; Public classRafdemo { Public Static voidMain (string[] args)throwsIOException {File demo=NewFile ("Demo"); if(!demo.exists ())        {Demo.mkdir (); } File File=NewFile (demo, "Raf.dat")); if(!file.exists ())        {File.createnewfile (); } Randomaccessfile RAF=NewRandomaccessfile (file, "RW");                System.out.println (Raf.getfilepointer ()); Raf.write (' A ');//One char takes two bytes, but write writes only one byte at a time (the last eight bits of the A character)System.out.println (Raf.getfilepointer ()); Raf.write (B); inti = 0x7fffffff; Raf.write (i>>> 24);//write high eight bits of IRaf.write (i >>> 16); Raf.write (i>> 8);        Raf.write (i);        System.out.println (Raf.getfilepointer ()); //write directly to an intRaf.writeint (i); String s= "You"; byte[] B =s.getbytes ("UTF8");        Raf.write (b);                System.out.println (Raf.length ()); //To read the file, you must move the pointer to the headRaf.seek (0); //One-time read to read the contents of a file into a byte array        byte[] buf =New byte[(int) Raf.length ()];        Raf.read (BUF);        System.out.println (arrays.tostring (BUF));  for(bytec:buf) {System.out.print (integer.tohexstring (c& 0xff) + ""); }        //Close FileRaf.close (); }}

Execution Result:

0 1 6  - [127,1,-1,-1127,-1 ,-1,-1,--  -----   7f FF FF FF  7f  FF FF  FF  e4  BD  A0  

Java-io Stream Randomaccessfile Class