Develop Reference

Java: Multi line output via Socket

i got some struggle with my code. I have to send some commands via client to a server (create a file or list files in the directory) the server should create the files or send a list of existing files back to the client. It worked, but i guess the while loop for output on client side never stops and the client cant input new commands. I dont get the problem :(. Many thanks in advance.
Server:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.BindException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.util.ArrayList;
import java.util.Arrays;
import java.io.File;
import java.io.FileWriter;
public class MyServer {
private final static String DIRECTORYLISTING = "directoryListing";
private final static String ADDFILE = "addFile";
private static String path = "/home/christoph/eclipse-workspace/Distributed Systems Ex 01/Work_Folder";
private static PrintWriter pw = null;
private static File file = null;
private static String command1 = null; // Command
private static String command2 = null; // File name
private static String command3 = null; // File content
private static ArrayList<File> files = new ArrayList<>(); //
public static void splitClientInput(String clientInput) {
try {
String [] splittedInput = clientInput.split(";");
command1=splittedInput[0];
command2=splittedInput[1];
command3=splittedInput[2];
} catch(ArrayIndexOutOfBoundsException e) {
e.printStackTrace();
}
}
public static void directoryListing() {
try {
File[] s = file.listFiles();
for(int i = 0; i<s.length;i++) {
pw.println(s[i].getName());
}
pw.flush();
}catch(NullPointerException e) {
e.printStackTrace();
}
}
public static void addFile(String command2,String command3) throws IOException {
file = new File(path +"/" +command2);
if(file.isFile()) {
pw.println("This Filename "+command2+" already exists.");
} else {
try {
FileWriter fileWriter = new FileWriter(file);
fileWriter.write(command3);
files.add(file);
pw.println(file.getName()+" created");
if(command3.equals(null)) {
pw.println("Your created file is empty");
}
fileWriter.close();
}catch(IOException e) {
pw.println("Error by creating file");
}catch (NullPointerException e) {
pw.println("Your created file is empty");
}
}
}
public static void checkInputCommand(String command1, String command2, String command3) throws IOException {
switch(command1) {
case DIRECTORYLISTING:
directoryListing();
break;
case ADDFILE:
addFile(command2, command3);
break;
}
}
public static void main(String[] args) {
try {
file = new File(path);
files = new ArrayList<File>(Arrays.asList(file.listFiles()));
ServerSocket ss = new ServerSocket(1118);
System.out.println("Server Started...");
Socket socket = ss.accept();
OutputStream os = socket.getOutputStream();
pw=new PrintWriter(os);
InputStream is = socket.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String clientInput = null;
while((clientInput = br.readLine()) != null) {
splitClientInput(clientInput);
checkInputCommand(command1, command2, command3);
pw.flush();
}
pw.flush();
br.close();
isr.close();
is.close();
pw.close();
os.close();
socket.close();
ss.close();
System.out.println("Server closed");
}catch(BindException e) {
e.printStackTrace();
}catch(SocketException e) {
e.printStackTrace();
}catch(java.lang.NullPointerException e) {
e.printStackTrace();
}catch (IOException e) {
e.printStackTrace();
}
}
}
Client:
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ConnectException;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;
public class MyClient {
public static void main(String[] args) throws Exception{
try {
Scanner sc = new Scanner(System.in);
Socket s = new Socket("127.0.0.1", 1118);
System.out.println("Client started");
InputStream is = s.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
OutputStream os = s.getOutputStream();
PrintWriter pw = new PrintWriter(os);
String str= null;
while(true){
System.out.print("Client input: ");
pw.println(sc.nextLine());
pw.flush();
// System.out.println(br.readLine());
/*
* dont get out of the loop?
*/
while((str=br.readLine())!=null) {
System.out.println(str);
}
br.close();
isr.close();
is.close();
s.close();
}
} catch(NullPointerException e) {
e.printStackTrace();
} catch(ConnectException e) {
e.printStackTrace();
}catch(UnknownHostException e) {
e.printStackTrace();
}catch (IOException e) {
e.printStackTrace();
}
}
}

How to copy files in Android in one go? Not create a tens lines of code! Smth like in a sample

I need to copy file from one place to another. I have found good solution :
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class FileCopyTest {
public static void main(String[] args) {
Path source = Paths.get("/Users/apple/Desktop/test.rtf");
Path destination = Paths.get("/Users/apple/Desktop/copied.rtf");
try {
Files.copy(source, destination);
} catch (IOException e) {
e.printStackTrace();
}
}
}
This library work good, but in doesn't available in Android...
I try figure out which way i should use instead of, but it any suggestion... I am almost sure that it should be a library which allow copy files in one go.
If someone know say please, i am sure it will be very helpful answer for loads of people.
Thanks!

Well with commons-io, you can do this
FileInputStream source = null;
FileOutputStream destination = null;
try {
source = new FileInputStream(new File(/*...*/));
destination = new FileOutputStream(new File(Environment.getExternalStorageDirectory(), /*...*/);
IOUtils.copy(source, destination);
} finally {
IOUtils.closeQuietly(source);
IOUtils.closeQuietly(destination);
}
Just add
compile 'org.apache.directory.studio:org.apache.commons.io:2.4'
to the build.gradle file

try this code
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.channels.FileChannel;
public class CopyFile {
public static void main(String[] args) {
File sourceFile = new File(
"/Users/Neel/Documents/Workspace/file1.txt");
File destFile = new File(
"/Users/Neel/Documents/Workspace/file2.txt");
/* verify whether file exist in source location */
if (!sourceFile.exists()) {
System.out.println("Source File Not Found!");
}
/* if file not exist then create one */
if (!destFile.exists()) {
try {
destFile.createNewFile();
System.out.println("Destination file doesn't exist. Creating
one!");
} catch (IOException e) {
e.printStackTrace();
}
}
FileChannel source = null;
FileChannel destination = null;
try {
/**
* getChannel() returns unique FileChannel object associated a file
* output stream.
*/
source = new FileInputStream(sourceFile).getChannel();
destination = new FileOutputStream(destFile).getChannel();
if (destination != null && source != null) {
destination.transferFrom(source, 0, source.size());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
finally {
if (source != null) {
try {
source.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (destination != null) {
try {
destination.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}

Use this utility class to read/write file in sdcard:
public class MyFile {
String TAG = "MyFile";
Context context;
public MyFile(Context context){
this.context = context;
}
public Boolean writeToSD(String text){
Boolean write_successful = false;
File root=null;
try {
// check for SDcard
root = Environment.getExternalStorageDirectory();
Log.i(TAG,"path.." +root.getAbsolutePath());
//check sdcard permission
if (root.canWrite()){
File fileDir = new File(root.getAbsolutePath());
fileDir.mkdirs();
File file= new File(fileDir, "samplefile.txt");
FileWriter filewriter = new FileWriter(file);
BufferedWriter out = new BufferedWriter(filewriter);
out.write(text);
out.close();
write_successful = true;
}
} catch (IOException e) {
Log.e("ERROR:---", "Could not write file to SDCard" + e.getMessage());
write_successful = false;
}
return write_successful;
}
public String readFromSD(){
File sdcard = Environment.getExternalStorageDirectory();
File file = new File(sdcard,"samplefile.txt");
StringBuilder text = new StringBuilder();
try {
BufferedReader br = new BufferedReader(new FileReader(file));
String line;
while ((line = br.readLine()) != null) {
text.append(line);
text.append('\n');
}
}
catch (IOException e) {
}
return text.toString();
}
#SuppressLint("WorldReadableFiles")
#SuppressWarnings("static-access")
public Boolean writeToSandBox(String text){
Boolean write_successful = false;
try{
FileOutputStream fOut = context.openFileOutput("samplefile.txt",
context.MODE_WORLD_READABLE);
OutputStreamWriter osw = new OutputStreamWriter(fOut);
osw.write(text);
osw.flush();
osw.close();
}catch(Exception e){
write_successful = false;
}
return write_successful;
}
public String readFromSandBox(){
String str ="";
String new_str = "";
try{
FileInputStream fIn = context.openFileInput("samplefile.txt");
InputStreamReader isr = new InputStreamReader(fIn);
BufferedReader br=new BufferedReader(isr);
while((str=br.readLine())!=null)
{
new_str +=str;
System.out.println(new_str);
}
}catch(Exception e)
{
}
return new_str;
}
}
Note you should give this permission in the AndroidManifest file.
Here permision
uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
For more details visit : http://www.coderzheaven.com/2012/09/06/read-write-files-sdcard-application-sandbox-android-complete-example/
Android developer official Docs

How to download file from FTP using Java?

With this code iI always get a empty file.
What I have to do with it?
login is always true. (ofc, here is not real password)
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import java.io.*;
public class Logs {
public static void main(String[] args) {
FTPClient client = new FTPClient();
try {
client.connect("myac.cs-server.pro", 121);
boolean login = client.login("a3ro", "passWordIsSecret");
System.out.println(login);
String remoteFile1 = "myac_20150304.log";
File downloadFile1 = new File("C:\\Users\\Aero\\Desktop\\test\\myac.log");
OutputStream outputStream1 =
new BufferedOutputStream(new FileOutputStream(downloadFile1));
boolean success = client.retrieveFile(remoteFile1, outputStream1);
System.out.println(success);
outputStream1.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
client.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}

Use FileOutputStream:
String filename = "test.txt";
FileOutputStream fos = new FileOutputStream(filename);
client.retrieveFile("/" + filename, fos);

Use something like this:
InputStream inputStream = client.retrieveFileStream(remoteFileNameHere);
To retrieve the remote file input stream.
Then you can use to copy the stream to desired file:
FileOutputStream out = new FileOutputStream(targetFile);
org.apache.commons.io.IOUtils.copy(in, out);

Parse a Path from Java program

Have a file on specified path /foo/file-a.txt and that file contains a path of another file
file-a.txt contains: /bar/file-b.txt this path at line one. need to parse the path of file-b.txt and zip that file and move that zipped file to another path /too/ from my Java code.
I been till the below code then i m stuck.
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class Reader
{
public static void main(String[] args)
{
BufferedReader br = null;
try
{
String CurrentLine;
br = new BufferedReader(new FileReader("/foo/file-a.txt"));
while ((CurrentLine = br.readLine()) != null)
{
System.out.println(CurrentLine);
}
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (br != null)br.close();
}
catch (IOException ex)
{
ex.printStackTrace();
}
}
}
}
am getting path as text, help would be appreciated. Thanks in advance

For the actual zipping of the file, this page may be of help.
As a general note, this code will replace the current existing zip file.
public class TestZip02 {
public static void main(String[] args) {
try {
zip(new File("TextFiles.zip"), new File("sample.txt"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
public static void zip(File zip, File file) throws IOException {
ZipOutputStream zos = null;
try {
String name = file.getName();
zos = new ZipOutputStream(new FileOutputStream(zip));
ZipEntry entry = new ZipEntry(name);
zos.putNextEntry(entry);
FileInputStream fis = null;
try {
fis = new FileInputStream(file);
byte[] byteBuffer = new byte[1024];
int bytesRead = -1;
while ((bytesRead = fis.read(byteBuffer)) != -1) {
zos.write(byteBuffer, 0, bytesRead);
}
zos.flush();
} finally {
try {
fis.close();
} catch (Exception e) {
}
}
zos.closeEntry();
zos.flush();
} finally {
try {
zos.close();
} catch (Exception e) {
}
}
}
}
For moving the file, you can use File.renameTo, here's an example.
Hope this helps!

reading and storing properties file

I am trying to update a value in property file through the following code
import java.io.*;
import java.util.Properties;
public class Sample {
public static void main(String a[]) throws IOException {
InputStream is = Sample.class.getClassLoader().getResourceAsStream("myfile.properties");
Properties p = new Properties();
p.load(is);
p.setProperty("myProperty", "updated");
OutputStream os = new FileOutputStream("myfile.properties");
p.store(os, "update");
os.close();
System.out.print(p.getProperty("myProperty"));
}
}
Output: updated
But the values doesn't seem to get updated. In Fact, I am not getting any error even if the property or the file itself is not present.

// Read properties file.
Properties prop = new Properties();
try {
prop.load(new FileInputStream("filename.properties"));
} catch (IOException e) {
}
// Write properties file.
try {
prop.store(new FileOutputStream("filename.properties"), null);
} catch (IOException e) {
}