Java Read and write

IO streams are divided into byte stream and character stream, and each stream is divided into input and output and read and write.

The two base classes for a byte stream are InputStream and outputstream.

Character stream for reader and writer

General buffered Stream read-write characters:

BufferedReader br = new BufferedReader (New FileReader ("B.txt"));

If you have an encoded format, use:

BufferedReader br = new BufferedReader (new InputStreamReader (New FileInputStream ("D:\\test\\xiong.txt"), "GBK"));

Reads the contents of a text, and randomly outputs a line of content.

 Public Static voidMain (string[] args)throwsIOException {bufferedreader br=NewBufferedReader (NewInputStreamReader (NewFileInputStream ("D:\\test\\xiong.txt"), "GBK")); ArrayList<String> list =NewArraylist<string>(); String Line=NULL;  while((Line=br.readline ())! =NULL) {List.add (line); }        intRandom =NewRandom (). Nextint (List.size ());    System.out.println (List.get (random)); }

Copy the files under the folder, there are photos in the file, video so use the byte stream:

 Packagecn;ImportJava.io.*; Public classFileDemo2 { Public Static voidMain (string[] args)throwsIOException {File Srcfolder=NewFile ("D:\\demo"); File Destfolder=NewFile ("D:\\test"); if(!destfolder.exists ())        {Destfolder.mkdir (); } file[] Files=Srcfolder.listfiles ();  for(file file:files) {file NewFile=NewFile (Destfolder, File.getname ());        Copy (file, newFile); }    }    Private Static voidCopy (file file, file NewFile)throwsioexception{Bufferedinputstream bis=NewBufferedinputstream (Newfileinputstream (file)); Bufferedoutputstream Bos=NewBufferedoutputstream (NewFileOutputStream (newFile)); intLen = 0; byte[] Bys =New byte[1024];  while((Len=bis.read (bys))!=-1) {bos.write (bys,0, Len); }
Bis.close ()
Bos.close ()
}}

Copy the text file that ends in. Java to another folder under one folder and end with a. Jad instead

 Packagecn;ImportJava.io.*;Importjava.util.ArrayList;ImportJava.util.Random;/*** Created by Administrator on 2015/3/11.*/ Public classFiledemo { Public Static voidMain (string[] args)throwsIOException {File Srcfolder=NewFile ("C:\\java"); File Destfolder=NewFile ("C:\\jad"); if(!(Destfolder.exists ()))        {Destfolder.mkdir (); } file[] Filearray= Srcfolder.listfiles (NewFilenameFilter () {@Override Public BooleanAccept (File dir, String name) {return NewFile (dir, name). Isfile () &&name.endswith (". Java");        }        });  for(File file:filearray) {String name=File.getname (); File NewFile=NewFile (Destfolder, name);        Copy (file, newFile); } file[] Destfilearray=Destfolder.listfiles ();  for(File destfile:destfilearray) {System.out.println (destfile); String name=Destfile.getname (); String NewName= Name.replace (". Java", ". Jad"); File NewFile=NewFile (Destfolder, newName);        Destfile.renameto (NewFile); }    }    Private Static voidCopy (file file, file NewFile)throwsioexception{Bufferedinputstream bis=NewBufferedinputstream (Newfileinputstream (file)); Bufferedoutputstream Bos=NewBufferedoutputstream (NewFileOutputStream (newFile)); intLen = 0; byte[] Bys =New byte[1024];  while((Len=bis.read (bys))!=-1) {bos.write (bys,0, Len);        } bis.close ();    Bos.close (); }}

Copy all content under a folder to the specified directory

 Packagecn;ImportJava.io.*;Importjava.util.ArrayList;ImportJava.util.Random;/*** Created by Administrator on 2015/3/11.*/ Public classFiledemo { Public Static voidMain (string[] args)throwsIOException {File srcfile=NewFile ("D:\\demos"); File DestFile=NewFile ("c:\\");    CopyFolder (Srcfile, destfile); }    Private Static voidCopyFolder (file srcfile, file destfile)throwsioexception{if(Srcfile.isdirectory ()) {File NewFolder=NewFile (DestFile, Srcfile.getname ());            Newfolder.mkdir (); File[] Filearray=Srcfile.listfiles ();  for(file File:filearray) {copyfolder (file, NewFolder); }        }Else{File NewFile=NewFile (DestFile, Srcfile.getname ());        CopyFile (Srcfile, newFile); }    }    Private Static voidCopyFile (file srcfile, file newFile)throwsioexception{bufferedoutputstream Bos=NewBufferedoutputstream (NewFileOutputStream (newFile)); Bufferedinputstream bis=NewBufferedinputstream (NewFileInputStream (srcfile)); intLen = 0; byte[] Bys =New byte[1024];  while((Len=bis.read (bys))!=-1) {bos.write (bys,0, Len);        } bis.close ();    Bos.close (); }}

Java Read and write