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Question about java IO FileInputStream written by myself

I wrote an example of FileInputStream,But I found that if I use read() directly in the loop, there will be a problem with the printed data, and it cannot be displayed completely. After using the int variable to receive the return value of read(), it can be displayed normally here. Why?
code:
String path = "d:/hello.txt";
FileInputStream fileInputStream = null;
int readData = 0;
try {
fileInputStream = new FileInputStream(path);
while ((readData = fileInputStream.read()) != -1) {
System.out.print((char) readData);
}
} catch (IOException e) {
throw new RuntimeException(e);
} finally {
try {
fileInputStream.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
}

How can I stream .mp3 files in Java?

I want to stream mp3 files and accessing them using spring, but i dont know how :( have already searched the internet but havent found anything yet. I already tried it using Streams and it worked kinda, but every song starts at the beginning and other people also start at the beginning of the song. My code:
Backend:
new Thread(() -> {
stream = new ByteArrayOutputStream();
while(true){
try {
currentSong = files[rd.nextInt(files.length-1)];
InputStream is = new FileInputStream(new File(currentSong));
int read = 0;
byte[] bytes = new byte[1024];
while((read = is.read(bytes)) !=-1){
stream.write(bytes, 0, read);
}
stream.flush();
is.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}).start();;
Frontend:
public class DnBController {
#GetMapping("/dnb")
public String play(HttpServletResponse httpServletResponse) throws IOException {
OutputStream os = httpServletResponse.getOutputStream();
httpServletResponse.setContentType("audio/mpeg");
DnbradioApplication.stream.writeTo(httpServletResponse.getOutputStream());
return "site.html";
}

StreamCorruptedException: invalid stream header: 79737200 when reading objects from a file

I create a client similarity, where clients register an account (an object is created) which is stored in a file.
Objects are written to the file as required, I override the writeStreamHeader() method. But when I try to read them all, their file throws an exception.
Write the objects to the file here.
public static void saveAccaunt(LoginAndPass gamers) {
boolean b = true;
FileInputStream fis = null;
try{
fis = new FileInputStream("student.ser");
fis.close();
}
catch (FileNotFoundException e)
{
b = false;
} catch (IOException e) {
e.printStackTrace();
}
try {
FileOutputStream fileOutputStream = new FileOutputStream("student.ser",true);
ObjectOutputStream os = null;
if(b = true){
os = new AppendingObjectOutputStream(fileOutputStream);
System.out.println("Объект добавлен!");
}else {
os = new ObjectOutputStream(fileOutputStream);
System.out.println("Создан");
}
os.writeObject(gamers);
os.close();
fileOutputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
try {
FileInputStream fileInputStream = new FileInputStream("student.ser");
ObjectInputStream objectInputStream = new ObjectInputStream(fileInputStream);
test = new ArrayList<>();
while (true){
test.add(objectInputStream.readObject());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println(test.get(0));
}
Here is the error log for the exception thrown:
java.io.StreamCorruptedException: invalid stream header: 79737200
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:866)
at java.io.ObjectInputStream.(ObjectInputStream.java:358)
at Registratsiya.AllGamers.main(AllGamers.java:48)
Exception in thread "main" java.lang.NullPointerException
at Registratsiya.AllGamers.main(AllGamers.java:61)

How to solve this Close this "FileOutputStream"

How to solve this?
I am getting the below error : Close this "FileOutputStream". but i have closes it already in finally block
public void initHistoryForOldFile(File oldFile, String filePath) throws PIDException {
InputStream inStream = null;
OutputStream outStream = null;
try {
File historyFile = new File(StringUtil.append(filePath, File.separator, "history"));
FileUtils.ensureDirectory(historyFile);
File oldHistoryFile = new File(StringUtil.append(filePath, File.separator, "history", File.separator, oldFile.getName()));
oldHistoryFile.createNewFile();
if (oldFile.exists()) {
inStream = new FileInputStream(oldFile);
outStream = new FileOutputStream(oldHistoryFile);
byte[] buffer = new byte[PIDConstants.IMAGE_FILE_SIZE_LIMIT];
int length;
// copy the file content in bytes
while ((length = inStream.read(buffer)) > 0) {
outStream.write(buffer, 0, length);
}
// delete the original file
oldFile.delete();
}
} catch (IOException e) {
LOGGER.error("Exception occured in historyUpdateForOldFIle", e);
} finally {
if (null != inStream) {
try {
inStream.close();
} catch (IOException e) {
LOGGER.error("Exception occured whole closing inStream", e);
}
}
if (null != outStream) {
try {
outStream.close();
} catch (IOException e) {
LOGGER.error("Exception occured whole closing outStream", e);
}
}
}
}

If using java 7
You can use Try with resources
try(InputStream inStream = new FileInputStream(oldFile)){}
The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with-resources statement ensures that each resource is closed at the end of the statement.

try(InputStream instream = new fileinputstream(oldFile)){};

How to download a text file via FTP and read the contents to a string

This is re-worded from a previous question (which was probably a bit unclear).
I want to download a text file via FTP from a remote server, read the contents of the text file into a string and then discard the file. I don't need to actually save the file.
I am using the Apache Commons library so I have:
import org.apache.commons.net.ftp.FTPClient;
Can anyone help please, without simply redirecting me to a page with lots of possible answers on?

Not going to do the work for you, but once you have your connection established, you can call retrieveFile and pass it an OutputStream. You can google around and find the rest...
FTPClient ftp = new FTPClient();
...
ByteArrayOutputStream myVar = new ByteArrayOutputStream();
ftp.retrieveFile("remoteFileName.txt", myVar);
ByteArrayOutputStream
retrieveFile

Normally I'd leave a comment asking 'What have you tried?'. But now I'm feeling more generous :-)
Here you go:
private void ftpDownload() {
FTPClient ftp = null;
try {
ftp = new FTPClient();
ftp.connect(mServer);
try {
int reply = ftp.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply)) {
throw new Exception("Connect failed: " + ftp.getReplyString());
}
if (!ftp.login(mUser, mPassword)) {
throw new Exception("Login failed: " + ftp.getReplyString());
}
try {
ftp.enterLocalPassiveMode();
if (!ftp.setFileType(FTP.BINARY_FILE_TYPE)) {
Log.e(TAG, "Setting binary file type failed.");
}
transferFile(ftp);
} catch(Exception e) {
handleThrowable(e);
} finally {
if (!ftp.logout()) {
Log.e(TAG, "Logout failed.");
}
}
} catch(Exception e) {
handleThrowable(e);
} finally {
ftp.disconnect();
}
} catch(Exception e) {
handleThrowable(e);
}
}
private void transferFile(FTPClient ftp) throws Exception {
long fileSize = getFileSize(ftp, mFilePath);
InputStream is = retrieveFileStream(ftp, mFilePath);
downloadFile(is, buffer, fileSize);
is.close();
if (!ftp.completePendingCommand()) {
throw new Exception("Pending command failed: " + ftp.getReplyString());
}
}
private InputStream retrieveFileStream(FTPClient ftp, String filePath)
throws Exception {
InputStream is = ftp.retrieveFileStream(filePath);
int reply = ftp.getReplyCode();
if (is == null
|| (!FTPReply.isPositivePreliminary(reply)
&& !FTPReply.isPositiveCompletion(reply))) {
throw new Exception(ftp.getReplyString());
}
return is;
}
private byte[] downloadFile(InputStream is, long fileSize)
throws Exception {
byte[] buffer = new byte[fileSize];
if (is.read(buffer, 0, buffer.length)) == -1) {
return null;
}
return buffer; // <-- Here is your file's contents !!!
}
private long getFileSize(FTPClient ftp, String filePath) throws Exception {
long fileSize = 0;
FTPFile[] files = ftp.listFiles(filePath);
if (files.length == 1 && files[0].isFile()) {
fileSize = files[0].getSize();
}
Log.i(TAG, "File size = " + fileSize);
return fileSize;
}

You can just skip the download to local filesystem part and do:
FTPClient ftpClient = new FTPClient();
try {
ftpClient.connect(server, port);
ftpClient.login(user, pass);
ftpClient.enterLocalPassiveMode();
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
InputStream inputStream = ftpClient.retrieveFileStream("/folder/file.dat");
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "Cp1252"));
while(reader.ready()) {
System.out.println(reader.readLine()); // Or whatever
}
inputStream.close();
} catch (IOException ex) {
ex.printStackTrace();
} finally {
try {
if (ftpClient.isConnected()) {
ftpClient.logout();
ftpClient.disconnect();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}