Develop Reference

Unable to serialize convert java POJO class into a byte array

How to convert java POJO class into a byte array as I wanted to save the object into a gz file in S3
I get this exception Caused by: java.io.NotSerializableException
public byte[] compressData(User user) throws IOException {
byte[] data;
try(ByteArrayOutputStream byteStream = new ByteArrayOutputStream();) {
try (GZIPOutputStream objectOutputStream = new GZIPOutputStream(byteStream);) {
try (ObjectOutputStream zipStream = new ObjectOutputStream(objectOutputStream);) {
zipStream.writeObject(user);
}
data = byteStream.toByteArray();
} catch (Exception e) {
throw new IOException(e);
}
}
return data;
}

you can use SerializationUtils.java from ApacheCommonslang dependency.
For serialization
byte[] data = SerializationUtils.serialize(**POJO_Object_Name**);
for deserialize:
POJO_Class_Name **POJO_Object_Name** = SerializationUtils.deserialize(data)

private final Type userType = new TypeToken<User>() {}.getType();
private final Gson = new Gson();
compressData(gson.toJson(user,userType));
public static byte[] compressData(String user) throws IOException {
byte[] data;
try(ByteArrayOutputStream byteStream = new ByteArrayOutputStream();){
try(GZIPOutputStream zipStream = new GZIPOutputStream(byteStream);){
zipStream.write(data.getBytes(StandardCharsets.UTF_8));
}
data = byteStream.toByteArray();
} catch(Exception e) {
throw new IOException("Error while compressing the User record ", e);
}
return data;
}

BufferedImage into Android bitmap

I've got a problem. I need to save a java BufferedImage object in an String. Convert this String on the Android application into Bitmap. How can I achieve this? Or maybe you can recommend me the other way to transfer image information in the String format.
public static String encodeToString(BufferedImage image, String type) {
String imageString = null;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
try {
ImageIO.write(image, type, bos);
byte[] imageBytes = bos.toByteArray();
imageString = Base64.getEncoder().encodeToString(imageBytes);
bos.close();
} catch (IOException e) {
log.error("Can't encode to String");
}
return imageString;
}

Base64 encoding and decoding of images using Java 8:
public static String imgToBase64String(final RenderedImage img, final String formatName) {
final ByteArrayOutputStream os = new ByteArrayOutputStream();
try {
ImageIO.write(img, formatName, Base64.getEncoder().wrap(os));
return os.toString(StandardCharsets.ISO_8859_1.name());
} catch (final IOException ioe) {
throw new UncheckedIOException(ioe);
}
}
public static BufferedImage base64StringToImg(final String base64String) {
try {
return ImageIO.read(new ByteArrayInputStream(Base64.getDecoder().decode(base64String)));
} catch (final IOException ioe) {
throw new UncheckedIOException(ioe);
}
}
hope so will work,
enjoy your code:)

Writing/Reading gif internal storage

I'm trying to load a gif from a url to be displayed in an Imageview, store it in the internal storage and then later read it again. But it refuses to either store the image or reading it, not sure which one because I get no exceptions. Loading the image to the imageview works. The first method below (loadImage())
public Bitmap loadImage(String url){
Bitmap bm = null;
URL request;
try {
if(url!=null){
request = new URL(url);
InputStream is = request.openStream();
bm = BitmapFactory.decodeStream(is);
is.close();
}
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return bm;
}
public String writeGifToInternalStorage (Bitmap outputImage) {
try {
String fileName = String.valueOf(Calendar.getInstance().getTimeInMillis());
ByteBuffer byteBuffer = ByteBuffer.allocate(outputImage.getByteCount());
outputImage.copyPixelsToBuffer(byteBuffer);
byteBuffer.flip();
byte[] data = new byte[byteBuffer.limit()];
byteBuffer.get(data);
FileOutputStream fos = ctx.openFileOutput(fileName, Context.MODE_PRIVATE);
fos.write(data);
fos.close();
return fileName;
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
public Bitmap readFileFromInternalStorage(String filename) {
if (filename == null) return null;
FileInputStream fis;
try {
fis = ctx.openFileInput(filename);
return BitmapFactory.decodeStream(fis);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return null;
}
Any ideas of whats wrong?

Your method readFileFromInternalStorage read an encoded image from the file system. This image file should be what you receive from the server.
For that, you need to save the image when you receive it from the server, for example like so:
InputStream is = new BufferedInputStream(request.openStream());
String fileName = String.valueOf(Calendar.getInstance().getTimeInMillis());
FileOutputStream fos = ctx.openFileOutput(fileName, Context.MODE_PRIVATE);
byte[] buffer = new byte[1024];
int red = 0;
while ((red = is.read(buffer)) != -1) {
fos.write(buffer,0, red);
}
fos.close();
is.close();
Then, your image is saved to the disk, and you can open it using your readFileFromInternalStorage method.
Also, if you use HttpClient instead of URL, I wrote a one-liner for downloading a file: Android download binary file problems

GZIP compression to a byte array

I am trying to write a class that can compress data. The below code fails (no exception is thrown, but the target .gz file is empty.)
Besides: I don't want to generate the .gz file directly like it is done in all examples. I only want to get the compressed
data, so that I can e.g. encrypt it before writting the data to a file.
If I write directly to a file everything works fine:
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
GZIPOutputStream zipStream = null;
FileOutputStream fileStream = null;
try
{
fileStream = new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
zipStream = new GZIPOutputStream(fileStream);
zipStream.write(dataToCompress);
fileStream.write(compressedData);
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
try{ zipStream.close(); }
catch(Exception e){ }
try{ fileStream.close(); }
catch(Exception e){ }
}
}
}
But, if I want to 'bypass' it to the byte array stream it does not produce a single byte - compressedData is always empty.
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
byte[] compressedData = null;
GZIPOutputStream zipStream = null;
ByteArrayOutputStream byteStream = null;
FileOutputStream fileStream = null;
try
{
byteStream = new ByteArrayOutputStream(dataToCompress.length);
zipStream = new GZIPOutputStream(byteStream);
zipStream.write(dataToCompress);
compressedData = byteStream.toByteArray();
fileStream = new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
fileStream.write(compressedData);
}
catch(Exception e)
{
e.printStackTrace();
}
finally
{
try{ zipStream.close(); }
catch(Exception e){ }
try{ byteStream.close(); }
catch(Exception e){ }
try{ fileStream.close(); }
catch(Exception e){ }
}
}
}

The problem is that you are not closing the GZIPOutputStream. Until you close it the output will be incomplete.
You just need to close it before reading the byte array. You need to reorder the finally blocks to achieve this.
import java.io.*;
import java.util.zip.*;
import java.nio.charset.*;
public class Zipper
{
public static void main(String[] args)
{
byte[] dataToCompress = "This is the test data."
.getBytes(StandardCharsets.ISO_8859_1);
try
{
ByteArrayOutputStream byteStream =
new ByteArrayOutputStream(dataToCompress.length);
try
{
GZIPOutputStream zipStream =
new GZIPOutputStream(byteStream);
try
{
zipStream.write(dataToCompress);
}
finally
{
zipStream.close();
}
}
finally
{
byteStream.close();
}
byte[] compressedData = byteStream.toByteArray();
FileOutputStream fileStream =
new FileOutputStream("C:/Users/UserName/Desktop/zip_file.gz");
try
{
fileStream.write(compressedData);
}
finally
{
try{ fileStream.close(); }
catch(Exception e){ /* We should probably delete the file now? */ }
}
}
catch(Exception e)
{
e.printStackTrace();
}
}
}
I do not recommend inititalizing the stream variables to null, because it means your finally block can also throw a NullPointerException.
Also note that you can declare main to throw IOException (then you would not need the outermost try statement.)
There is little point in swallowing exceptions from zipStream.close();, because if it throws an exception you will not have a valid .gz file (so you should not proceed to write it.)
Also I would not swallow exceptions from byteStream.close(); but for a different reason - they should never be thrown (i.e. there is a bug in your JRE and you would want to know about that.)

I've improved JITHINRAJ's code - used try-with-resources:
private static byte[] gzipCompress(byte[] uncompressedData) {
byte[] result = new byte[]{};
try (ByteArrayOutputStream bos = new ByteArrayOutputStream(uncompressedData.length);
GZIPOutputStream gzipOS = new GZIPOutputStream(bos)) {
gzipOS.write(uncompressedData);
// You need to close it before using bos
gzipOS.close();
result = bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
private static byte[] gzipUncompress(byte[] compressedData) {
byte[] result = new byte[]{};
try (ByteArrayInputStream bis = new ByteArrayInputStream(compressedData);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
GZIPInputStream gzipIS = new GZIPInputStream(bis)) {
byte[] buffer = new byte[1024];
int len;
while ((len = gzipIS.read(buffer)) != -1) {
bos.write(buffer, 0, len);
}
result = bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}

If you are still looking an answer you can use the below code to get the compressed byte[] using deflater and decompress it using inflater.
public static void main(String[] args) {
//Some string for testing
String sr = new String("fsdfesfsfdddddddsfdsfssdfdsfdsfdsfdsfdsdfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggghghghghggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggfsdfesfsfdddddddsfdsfssdfdsfdsfdsfdsfdsdfggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggggghghghghggggggggggggggggggggggggggggggggggggggggg");
byte[] data = sr.getBytes();
System.out.println("src size "+data.length);
try {
compress(data);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static byte[] compress(byte[] data) throws IOException {
Deflater deflater = new Deflater();
deflater.setInput(data);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream(data.length);
deflater.finish();
byte[] buffer = new byte[1024];
while (!deflater.finished()) {
int count = deflater.deflate(buffer);
outputStream.write(buffer, 0, count);
}
outputStream.close();
byte[] output = outputStream.toByteArray();
System.out.println("Original: " + data.length );
System.out.println("Compressed: " + output.length );
return output;
}

To compress
private static byte[] compress(byte[] uncompressedData) {
ByteArrayOutputStream bos = null;
GZIPOutputStream gzipOS = null;
try {
bos = new ByteArrayOutputStream(uncompressedData.length);
gzipOS = new GZIPOutputStream(bos);
gzipOS.write(uncompressedData);
gzipOS.close();
return bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
finally {
try {
assert gzipOS != null;
gzipOS.close();
bos.close();
}
catch (Exception ignored) {
}
}
return new byte[]{};
}
To uncompress
private byte[] uncompress(byte[] compressedData) {
ByteArrayInputStream bis = null;
ByteArrayOutputStream bos = null;
GZIPInputStream gzipIS = null;
try {
bis = new ByteArrayInputStream(compressedData);
bos = new ByteArrayOutputStream();
gzipIS = new GZIPInputStream(bis);
byte[] buffer = new byte[1024];
int len;
while((len = gzipIS.read(buffer)) != -1){
bos.write(buffer, 0, len);
}
return bos.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
finally {
try {
assert gzipIS != null;
gzipIS.close();
bos.close();
bis.close();
}
catch (Exception e) {
e.printStackTrace();
}
}
return new byte[]{};
}

You can use the below function, it is tested and working fine.
In general, your code has serious problem of ignoring the exceptions! returning null or simply not printing anything in the catch block will make it very difficult to debug
You do not have to write the zip output to a file if you want to process it further (e.g. encrypt it), you can easily modify the code to write the output to in-memory stream
public static String zip(File inFile, File zipFile) throws IOException {
FileInputStream fis = new FileInputStream(inFile);
FileOutputStream fos = new FileOutputStream(zipFile);
ZipOutputStream zout = new ZipOutputStream(fos);
try {
zout.putNextEntry(new ZipEntry(inFile.getName()));
byte[] buffer = new byte[BUFFER_SIZE];
int len;
while ((len = fis.read(buffer)) > 0) {
zout.write(buffer, 0, len);
}
zout.closeEntry();
} catch (Exception ex) {
ex.printStackTrace();
return null;
} finally {
try{zout.close();}catch(Exception ex){ex.printStackTrace();}
try{fis.close();}catch(Exception ex){ex.printStackTrace();}
}
return zipFile.getAbsolutePath();
}

Most of the examples have wrong exception handling.
public static byte[] gzipBytes(byte[] payload) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try (GZIPOutputStream gzip = new GZIPOutputStream(baos)) {
gzip.write(payload);
} catch (IOException e) {
throw new UncheckedIOException(e);
}
// note: toByteArray should be called after try-with-resources, not inside
return baos.toByteArray();
}
public static byte[] gunzipBytes(byte[] gzPayload) {
ByteArrayInputStream bais = new ByteArrayInputStream(gzPayload);
try (GZIPInputStream gzip = new GZIPInputStream(bais)) {
// java 9+ required for this method
return gzip.readAllBytes();
} catch (IOException e) {
throw new UncheckedIOException("Error while unpacking gzip content", e);
}
}

Try with this code..
try {
String inputFileName = "test.txt"; //may use your file_Path
String zipFileName = "compressed.zip";
//Create input and output streams
FileInputStream inStream = new FileInputStream(inputFileName);
ZipOutputStream outStream = new ZipOutputStream(new FileOutputStream(zipFileName));
// Add a zip entry to the output stream
outStream.putNextEntry(new ZipEntry(inputFileName));
byte[] buffer = new byte[1024];
int bytesRead;
//Each chunk of data read from the input stream
//is written to the output stream
while ((bytesRead = inStream.read(buffer)) > 0) {
outStream.write(buffer, 0, bytesRead);
}
//Close zip entry and file streams
outStream.closeEntry();
outStream.close();
inStream.close();
} catch (IOException ex) {
ex.printStackTrace();
}
Also may be helpful this one..
http://www.java-samples.com/java/zip_files_in_a_folder_using_java.htm

(how) can I download an image using JSoup?

I already know where the image is, but for simplicity's sake I wanted to download the image using JSoup itself. (This is to simplify getting cookies, referrer, etc.)
This is what I have so far:
//Open a URL Stream
Response resultImageResponse = Jsoup.connect(imageLocation).cookies(cookies).ignoreContentType(true).execute();
// output here
OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(new java.io.File(outputFolder + name));
//BufferedWriter out = new BufferedWriter(new FileWriter(outputFolder + name));
out.write(resultImageResponse.body()); // resultImageResponse.body() is where the image's contents are.
out.close();

I didn't even finish writing the question before I found the answer via JSoup and a little experimentation.
//Open a URL Stream
Response resultImageResponse = Jsoup.connect(imageLocation).cookies(cookies)
.ignoreContentType(true).execute();
// output here
FileOutputStream out = (new FileOutputStream(new java.io.File(outputFolder + name)));
out.write(resultImageResponse.bodyAsBytes()); // resultImageResponse.body() is where the image's contents are.
out.close();

Simply you can use these methods-
public static String storeImageIntoFS(String imageUrl, String fileName, String relativePath) {
String imagePath = null;
try {
byte[] bytes = Jsoup.connect(imageUrl).ignoreContentType(true).execute().bodyAsBytes();
ByteBuffer buffer = ByteBuffer.wrap(bytes);
String rootTargetDirectory = IMAGE_HOME + "/"+relativePath;
imagePath = rootTargetDirectory + "/"+fileName;
saveByteBufferImage(buffer, rootTargetDirectory, fileName);
} catch (IOException e) {
e.printStackTrace();
}
return imagePath;
}
public static void saveByteBufferImage(ByteBuffer imageDataBytes, String rootTargetDirectory, String savedFileName) {
String uploadInputFile = rootTargetDirectory + "/"+savedFileName;
File rootTargetDir = new File(rootTargetDirectory);
if (!rootTargetDir.exists()) {
boolean created = rootTargetDir.mkdirs();
if (!created) {
System.out.println("Error while creating directory for location- "+rootTargetDirectory);
}
}
String[] fileNameParts = savedFileName.split("\\.");
String format = fileNameParts[fileNameParts.length-1];
File file = new File(uploadInputFile);
BufferedImage bufferedImage;
InputStream in = new ByteArrayInputStream(imageDataBytes.array());
try {
bufferedImage = ImageIO.read(in);
ImageIO.write(bufferedImage, format, file);
} catch (IOException e) {
e.printStackTrace();
}
}