Java for file read and write operation detailed _java

Directly on the code, there are detailed comments, there are illustrations, I believe you understand!

Copy Code code as follows:

Package day14;

Import Java.io.BufferedReader;
Import Java.io.BufferedWriter;
Import Java.io.File;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import Java.io.FileReader;
Import Java.io.FileWriter;
Import java.io.IOException;
Import Java.io.InputStream;
Import java.util.Enumeration;
Import Java.util.Random;
Import Java.util.zip.ZipEntry;
Import java.util.zip.ZipException;
Import Java.util.zip.ZipFile;

public class Testfileio {
Static String s = file.separator;

private static void Testinput () {
There is a Welcome.java file under D disk, now read by byte:
int a = 0;
int counter=0;
FileInputStream F11;
Input stream
try {
F11 = new FileInputStream ("D:" + S + "Welcome.java");
while ((A = F11.read ())!=-1)
System.out.print ((char) a); Here is the byte output, the Chinese character does not output normally, because one of the Chinese characters characters two bytes.
System.out
. println ("\ n \--------------------------------------------------\ n");

FileReader f12 = new FileReader ("D:" + S + "Welcome.java");
while ((A = F12.read ())!=-1)
System.out.print ((char) a);//Here is the character output, the Chinese characters can be output normally
System.out
. println ("\ n \--------------------------------------------------\ n");

F11.close () to close the file after you finish reading
F12.close () to close the file after you finish reading
catch (FileNotFoundException e) {
TODO auto-generated Catch block
E.printstacktrace ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}

private static void Testoutput () {
There is a Welcome.java file under D disk, now read by byte:
int a = 0;
Output stream
The file F21 = new file ("D:" + S + "testfile" + S + "Test1.txt"),//define the F21 of the document, and then determine if it exists in this directory, and if not, create it.
if (!f21.exists ()) {
F21.getparentfile (). Mkdirs ();
try {
F21.createnewfile ();
Copy the contents of "Welcome.java" to F21
FileOutputStream fos = new FileOutputStream (F21);
FileInputStream fis = new FileInputStream ("D:" + S
+ "Welcome.java");/read "Welcome.java" file
while ((A = Fis.read ())!=-1)
Fos.write (a);//writes the read memory into the FOS, the test1 is now obtained. TXT is copy welcome. of Java

Writer class
FileWriter f22 = new FileWriter ("D:" + S + "testfile" + S
+ "Test2.txt");
for (int i = 0; i < 65535; i++)
F22.write (i)//Will
Written to the Test2.txt. It can also be seen from here that the above 35-38 lines to determine whether a file exists or not.
Writing a string to a file
FileWriter f23 = new FileWriter ("D:" + S + "testfile" + S
+ "Test3.txt");
F23.write ("Hello, world!");

Fos.close ();
Fis.close ();
F22.close ();
F23.close ();
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}
}

private static void Testbufferring () {
There is a Welcome.java file under D disk, now read by byte:
int a = 0, counter = 0;
Buffer characters for efficient writing
BufferedWriter f31=new BufferedWriter (new
FileWriter ("D" +s+ "testfile" +s+ "Test4.txt"));
BufferedWriter f31;
try {
F31 = new BufferedWriter (New FileWriter ("D:" + S + "testfile" + S
+ "Test4.txt"));
for (int i = 1; I <= i++) {
F31.write (string.valueof (New Random (). Nextint (100)) + "");
if (i% 10 = 0)
F31.newline ();
}
F31.flush ()//Refresh Buffer
F31.close ();

BufferedReader F32 = new BufferedReader (New FileReader ("D:" + S
+ "Testfile" + S + "test4.txt");
String S32;
System.out.println ("Content of output file F32:");
while ((S32 = F32.readline ())!= null)
System.out.println (S32);
F32.close ();
System.out
. println ("\ n--------------------------------------------------\ n");
catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}

private static void Testzip () {
try {
File F1 = new file ("D:/test.zip");
File F2 = new file ("D:/testfile/testzip");
ZipFile ZF = new ZipFile (F1);
Testziptounzip (ZF, F2);

catch (IOException e) {
TODO auto-generated Catch block
E.printstacktrace ();
}
}

Extract the compressed package zipfile into file
public static void Testziptounzip (ZipFile zipfile, file file) {
ZipEntry zentry = null;
File zipout;
InputStream zis = null;
FileOutputStream fos = null;
Directory of Enumeration E = Zipfile.entries ();//ZipFile

while (E.hasmoreelements ()) {
Zentry = (zipentry) e.nextelement ();
System.out.println (Zentry.getname ());//What are the files under ZipFile? But why not output in order??

Place the extracted files under the file folder:
zipout = new File (file + S + zentry.getname ());

if (!zentry.isdirectory ()) {
try {
ZiS = Zipfile.getinputstream (zentry);
if (!zipout.exists ())
Zipout.getparentfile (). Mkdirs ();
FOS = new FileOutputStream (zipout);
Byte[] B = new byte[1024];
int length;
while (length = Zis.read (b)) > 0) {
Fos.write (b, 0, length);
}
Fos.close ();
Zis.close ();
catch (Zipexception E1) {
TODO auto-generated Catch block
E1.printstacktrace ();
catch (IOException E1) {
TODO auto-generated Catch block
E1.printstacktrace ();
}
}
}
}

public static void Main (string[] args) throws Zipexception {
TODO auto-generated Method Stub

Testinput ();
Testoutput ();
Testbufferring ();
Testzip ();
}
}