Io stream file read, write, and copy __java in Java

Construct File class

File F=new file (fileName);

To determine whether a directory

F.isdirectory ();

Get the file name under the directory

String[] Filename=f.list ();

Get the files in the directory
File[] Files=f.listfiles ();

1, Java How to read files

Package com.yyb.file;

Import Java.io.File;
Import Java.io.FileInputStream;
Import Java.io.InputStream;

*
 * Read the file:
 * 1, find the specified file
 * 2, according to the file creation file input stream
 * 3, create byte array
 * 4, read content, put in byte array
 * 5, close the input stream
* * public class Fileread {public

	static void Main (string[] args) {
		//build the specified file
		= filename = new ("E:" + file . Separator + "Hello.txt");
		InputStream in = null;
		try {
			//The input stream in
			= new FileInputStream (file) based on file creation files;
			Create byte array
			byte[] data = new byte[1024];
			Read the content and put it into the byte array
			in.read (data);
			System.out.println (new String (data));
		catch (Exception e) {
			e.printstacktrace ();
		} finally {
			try {
				//Close input stream
				in.close ();
			} catch (Exception e) {
				e.printstacktrace ();}}}

2, Java How to write files

Package com.yyb.file;

Import Java.io.File;
Import Java.io.FileOutputStream;
Import Java.io.OutputStream;

*
 * Write to File:
 * 1, find the specified file
 * 2, according to file creation file output stream
 * 3, convert content to byte array
 * 4, write content to file
 * 5, close the input
 stream
public class FileWriter {public

	static void Main (string[] args) {
		//build the specified file
		= filename = new ("E:" + Fi Le.separator + "Hello.txt");
		OutputStream out = null;
		try {
			//The output stream of the file created by the file
			= new FileOutputStream (file);
			String message = "I am a good man." ";
			Convert content to byte array
			byte[] data = Message.getbytes ();
			Write content to file
			out.write (data),
		catch (Exception e) {
			e.printstacktrace ();
		} finally {
			try {
				//Turn off output stream
				out.close ();
			} catch (Exception e) {
				e.printstacktrace ()

}}}}

3, Java How to copy files

<span style= "FONT-SIZE:18PX;"

>package Com.yyb.file;
Import Java.io.File;
Import Java.io.FileInputStream;
Import Java.io.FileOutputStream;
Import Java.io.InputStream;
Import Java.io.OutputStream; * * Implementation of ideas: * 1, build source file and target file * 2, source file Create input stream, target file Create output stream * 3, create byte array * 4, use loop, source file read part of content, target file write part of content, until all content is finished * 5, close source file input stream, target File output stream/public class FileCopy {public static void main (string[] args) {//build source files = new file ("E:" + file
		. Separator + "HelloWorld.txt");
		Build target file FileCopy = new file ("D:" + file.separator + "HelloWorld");
		InputStream in = null;
		OutputStream out = null; The try {//destination file does not exist to create an if (!) (
			Filecopy.exists ()) {filecopy.createnewfile ());
			///source file Create input stream in = new FileInputStream (file);
			Target file creation output stream out = new FileOutputStream (FileCopy, true);
			Create byte array byte[] temp = new byte[1024];
			int length = 0;
			The source file reads part of the content while (length = in.read (temp))!=-1) {//The target file is written to part Out.write (temp, 0, length); }} CATCH (Exception e) {e.printstacktrace ();
				Finally {try {//close file Input output stream in.close ();
			Out.close ();
			catch (Exception e) {e.printstacktrace (); }}}</span><span style= "FONT-SIZE:24PX;" > </span>