Learn, develop, play.
We are having 2 variants:
1 – when we want to create single folder (C:\first)
2 – when we want to create all tree for folders (C:\1\2\3)
Let’s try to create it:
//First variant
File folder= new File("C:\\first");
file.mkdir();
//Second variant
File folders= new File("C:\\1\\2\\3");
files.mkdirs();
After that we will see all folder which we want.
Previous we just create empty temp file
Lets write there some text
Example:
try{
File tempFile = File.createTempFile("tempFile", ".tmp");
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(tempFile));
bufferedWriter.write("This is Test for tempFile!");
bufferedWriter.close();
}catch(IOException ex){
ex.printStackTrace();
}
Sometimes you need to crate temp files and clean memory
java.io.File library helps to do this
Example:
try{
File tempFile = File.createTempFile("tempFileName", ".tmp");
System.out.println(tempFile.getAbsolutePath());
}catch(IOException ex){
ex.printStackTrace();
}
This code create file like tempFileName31231.tmp
We have already zip file in GZip format, lets unzip it
Example:
String INPUT_FILE = "/home/user/fileArchive.gz";
String OUTPUT_FILE = "/home/user/fileText.txt";
byte[] buffer = new byte[1024];
try{
GZIPInputStream gZIPInputStream = new GZIPInputStream(new FileInputStream(INPUT_FILE));
FileOutputStream fileOutputStream = new FileOutputStream(OUTPUT_FILE);
int len;
while ((len = gZIPInputStream.read(buffer)) > 0) {
fileOutputStream.write(buffer, 0, len);
}
gZIPInputStream.close();
fileOutputStream.close();
}catch(IOException ex){
ex.printStackTrace();
}
We have already create zip file in java, lets check it with GZip
Example:
private String OUTPUT_FILE = "/home/user/fileArchive.gz";
private String INPUT_FILE = "/home/user/fileText.txt";
byte[] buffer = new byte[1024];
try{
GZIPOutputStream gZIPOutputStream = new GZIPOutputStream(new FileOutputStream(OUTPUT_FILE));
FileInputStream fileInputStream = new FileInputStream(INPUT_FILE);
int len;
while ((len = fileInputStream.read(buffer)) > 0) {
gZIPOutputStream.write(buffer, 0, len);
}
fileInputStream.close();
gZIPOutputStream.finish();
gZIPOutputStream.close();
}catch(IOException ex){
ex.printStackTrace();
}
UnZip file in java not so easy like pack it.
Example
String zipFile="C:\\MyFile.zip";
String outputFolder="C:\\outputzip";
byte[] buffer = new byte[1024];
try{
File folder = new File(outputFolder);
if(!folder.exists()){
folder.mkdir();
}
ZipInputStream zis = new ZipInputStream(new FileInputStream(zipFile));
ZipEntry ze = zis.getNextEntry();
while(ze!=null){
String fileName = ze.getName();
File newFile = new File(outputFolder + File.separator + fileName);
System.out.println("file unzip : "+ newFile.getAbsoluteFile());
new File(newFile.getParent()).mkdirs();
FileOutputStream fos = new FileOutputStream(newFile);
int len;
while ((len = zis.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
fos.close();
ze = zis.getNextEntry();
}
zis.closeEntry();
zis.close();
System.out.println("Done");
}catch(IOException ex){
ex.printStackTrace();
}
Java core has library for zip packing, it is java.util.zip
Here short example
byte[] buffer = new byte[1024];
try{
FileOutputStream fileOutputStream = new FileOutputStream("C:\\myFile.zip");
ZipOutputStream zipOutputStream = new ZipOutputStream(fileOutputStream );
ZipEntry zipEntry = new ZipEntry("myLog.log");
zipOutputStream.putNextEntry(zipEntry );
FileInputStream fileInputStream= new FileInputStream("C:\\myLog.log");
int len;
while ((len = in.read(buffer)) > 0) {
zipOutputStream .write(buffer, 0, len);
}
in.close();
zipOutputStream.closeEntry();
zipOutputStream.close();
}catch(IOException e){
e.printStackTrace();
}
Like in last example we using java core library FileOutputStream
here example
FileInputStream fileInputStream=null;
File myFile = new File("C:\\myFile.txt");
byte[] byteFile = new byte[(int) myFile.length()];
try {
fileInputStream = new FileInputStream(myFile);
fileInputStream.read(byteFile);
fileInputStream.close();
FileOutputStream fileOuputStream = new FileOutputStream("C:\\toFile.txt");
fileOuputStream.write(bFile);
fileOuputStream.close();
}catch(Exception ex){
ex.printStackTrace();
}
For this activity we using library FileInputStream
here simple example for this
FileInputStream fileInputStream=null;
File myFile = new File("C:\\myFile.txt");
byte[] byteFile = new byte[(int) myFile.length()];
try {
fileInputStream = new FileInputStream(myFile);
fileInputStream.read(byteFile);
fileInputStream.close();
for (int i = 0; i < byteFile.length; i++) { System.out.print((char)byteFile[i]); } }catch(Exception ex){ ex.printStackTrace(); }
It is simple example for generating checksum in java
String myFile= "c:\\myFile.TXT";
MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
FileInputStream fileInputStream = new FileInputStream(myFile);
byte[] dataBytes = new byte[1024];
int nread = 0;
while ((nread = fileInputStream.read(dataBytes)) != -1) {
messageDigest.update(dataBytes, 0, nread);
};
byte[] mdbytes = messageDigest.digest();
StringBuffer sb = new StringBuffer("");
for (int i = 0; i < mdbytes.length; i++) {
sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
}
System.out.println(sb.toString());
In the en you will see checksum