Javase (9) _java IO system

first, the file class

1. File can represent the name of a particular file, or the name of a group of files under a directory, in fact, FilePath is a better name for this class.
2. Directory List Example:

ImportJava.io.File;ImportJava.io.FilenameFilter;Importjava.util.Arrays;ImportJava.util.regex.Pattern; Public classDirlist { Public Static voidMain (string[] args) {File path=NewFile ("./data/baiduvideo/"));        String[] list; if(Args.length = = 0) List=path.list (); Else{List= Path.list (NewDirfilter (args[0])); } arrays.sort (List,string.case_insensitive_order);//Sort By letter         for(String diritem:list) System.out.println (Diritem); }}classDirfilterImplementsFilenameFilter {Privatepattern pattern;  PublicDirfilter (String regex) {pattern=pattern.compile (regex); } @Override Public BooleanAccept (File dir, String name) {returnpattern.matcher (name). matches (); }}//This is the internal implementation of the list method, the policy design pattern/*Public string[] List (FilenameFilter filter) {String names[] = list (); if ((names = = null) | | (filter = = null))    {return names;    } ArrayList v = new ArrayList ();    for (int i = 0; i < names.length; i++) {if (Filter.accept (this, names[i]) {V.add (names[i]); }} return (string[]) (V.toarray (New String[v.size ()));}*///anonymous internal class rewrite, poor readability Public classDirlist { Public Static voidMainFinalstring[] args) {File path=NewFile ("./data/baiduvideo/"));        String[] list; if(Args.length = = 0) List=path.list (); Else{List= Path.list (NewFilenameFilter () {PrivatePattern pattern = Pattern.compile (args[0]); @Override Public BooleanAccept (File dir, String name) {returnpattern.matcher (name). matches ();        }            }); } arrays.sort (List,string.case_insensitive_order);//Sort By letter         for(String diritem:list) System.out.println (Diritem); }}

Other common uses of the file class are slightly.

Second, IO basic use

 PackageTestio;ImportJava.io.BufferedReader;ImportJava.io.BufferedWriter;ImportJava.io.ByteArrayInputStream;ImportJava.io.DataInputStream;ImportJava.io.FileReader;ImportJava.io.FileWriter;Importjava.io.IOException;ImportJava.io.PrintWriter;ImportJava.io.StringReader; Public classBufferedinputfile {//1. Buffered input file     Public StaticString read (string filename)throwsioexception{//BufferedReader is designed to improve performanceBufferedReader in =NewBufferedReader (Newfilereader (filename));        String s; StringBuilder SB=NewStringBuilder ();  while((S=in.readline ())! =NULL) Sb.append (s); Sb.append ("\ n");//ReadLine has deleted the line breakIn.close (); returnsb.tostring (); }     Public Static voidMain (string[] args)throwsIOException {System.out.println (read ("E:/eclipse/testnginx/src/testio/bufferedinputfile.java")); }} Public classMemoryinput {//2. Input from memory     Public Static voidMain (string[] args)throwsIOException {StringReader in=NewStringReader (bufferedinputfile. Read ("E:/eclipse/testnginx/src/testio/memoryinput.java")); intC;  while((c = In.read ())! = 1) System.out.print (Char) c); }} Public classFormattedmemoryinput {//3, formatted memory input--read characters in bytes, prevent garbled     Public Static voidMain (string[] args)throwsIOException {DataInputStream in=NewDataInputStream (NewBytearrayinputstream (Bufferedinputfile.read ("E:/eclipse/testnginx/src/testio/memoryinput.java"). GetBytes ()));  while(true) System.out.print (Char) In.readbyte ()); }} Public classBasicfileoutput {//1, basic text output, in order to provide a format mechanism, the use of PrintWriter    /*static String file = "Basicfileoutput.out";                public static void Main (string[] args) throws IOException {BufferedReader in = new BufferedReader (New FileReader (        "E://eclipse//testnginx//src//testio//basicfileoutput.java"));        PrintWriter out = new PrintWriter (new BufferedWriter (new FileWriter (file));        String s;        int linecount = 1;        while ((s = in.readline ()) = null) out.println (linecount++ + ":" + s);        Out.close ();    In.close (); }*/    //mode 2 input from memory    StaticString file = "Basicfileoutput.out";  Public Static voidMain (string[] args)throwsIOException {BufferedReader in=NewBufferedReader (NewStringReader (Bufferedinputfile.read ("E:/eclipse/testnginx/src/testio/basicfileoutput.java"))); PrintWriter out=NewPrintWriter (NewBufferedWriter (NewFileWriter (file)); //PrintWriter out = new PrintWriter (file);//a quick way to PrintWriterString S; intLineCount = 1;  while((s = in.readline ())! =NULL) out.println (LineCount++ + ":" +s);        Out.close ();    In.close (); }}

Javase (9) _java IO system