Develop Reference

The file gets smaller after reading the jar package and writing it to another file

package com.example.demo.Util;
public class Test {
static HashMap<String,String> map = new HashMap<>();
public static void main(String[] args) throws IOException {
String data = "12j3h1i7tsa7sgdajk123y8asd: 88888";
File jarFile = new File(new Test().getJarPath());
File tempJar = upJarFile(jarFile, "BOOT-INF/classes/application.properties", data);
}
public static File upJarFile(File originalJarFile, String editFilePath, String content) throws IOException {
File tempFile = File.createTempFile("temp", ".jar");
JarFile jarFile = new JarFile(originalJarFile);
Enumeration<JarEntry> entries = jarFile.entries();
System.out.println("before:"+ originalJarFile.length());
JarOutputStream jarOutputStream = new JarOutputStream(new FileOutputStream(tempFile));
while (entries.hasMoreElements()) {
JarEntry jarEntry = entries.nextElement();
jarOutputStream.putNextEntry(jarEntry);
map.put(jarEntry.getName(), String.valueOf(jarEntry.getSize()));
jarOutputStream.write(new Test().inputStreamToByteArray(jarFile.getInputStream(jarEntry)));
}
jarOutputStream.finish();
jarOutputStream.close();
System.out.println(tempFile.getPath());
System.out.println("after:" + tempFile.length());
return tempFile;
}
public String getJarPath() {
String path1 = System.getProperty("user.dir");
File file = new File(path1 + "/target/");
String jarFile = null;
for (File file1 : file.listFiles()) {
if (file1.getName().endsWith(".jar")) {
jarFile = file1.getPath();
break;
}
}
return jarFile;
}
public byte[] inputStreamToByteArray(InputStream inputStream) {
try (ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream()) {
byte[] buffer = new byte[1024];
int num;
while ((num = inputStream.read(buffer)) != -1) {
byteArrayOutputStream.write(buffer, 0, num);
}
byteArrayOutputStream.flush();
return byteArrayOutputStream.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return new byte[]{};
}
}
As shown in the code above,I just turn the incoming jar packages into streams and write them one by one,But it got smaller when I tested the size of the input package and the size of the output temporary package(before:49651057-->after:49647985)
What could be causing this difference?

This can happen due to a number of reasons:
The original JAR file was created with a compression level that is not as high as the default compression level, so the JAR file that you create (with default compression) achieves better compression, and therefore it is smaller. You can verify this by opening both the original and the result JAR files with a ZIP utility (e.g. 7Zip) and examining their checksums and their compressed sizes. If the checksums are identical, but the compressed sizes differ, then the difference is simply due to better compression.
The original JAR file contains unused data. This can happen when sloppy archive creation software updates an archive by appending to it instead of rewriting it from scratch. You can verify this by opening the original ZIP archive with a ZIP utility (e.g. 7Zip) and saving it under a new filename. If the new file is smaller, then the original file contained some unused data.
The original JAR file contains files in subdirectories, which you are not checking. Thus, your output JAR file does not contain all of the files in the original. To fix this, you need to check each entry with jarEntry.isDirectory() and if so, recurse.

Getting the list of filenames from resource folder when running in jar

I have some Json files in the folder "resource/json/templates". I want to read these Json files. So far, the snippet of code below is allowing me to do so when running the program in IDE but it fails when I run it in the jar.
JSONParser parser = new JSONParser();
ClassLoader loader = getClass().getClassLoader();
URL url = loader.getResource(templateDirectory);
String path = url.getPath();
File[] files = new File(path).listFiles();
PipelineTemplateRepo pipelineTemplateRepo = new PipelineTemplateRepoImpl();
File templateFile;
JSONObject templateJson;
PipelineTemplateVo templateFromFile;
PipelineTemplateVo templateFromDB;
String templateName;
for (int i = 0; i < files.length; i++) {
if (files[i].isFile()) {
templateFile = files[i];
templateJson = (JSONObject) parser.parse(new FileReader(templateFile));
//Other logic
}
}
}
catch (Exception e) {
e.printStackTrace();
}
Any help would be greatly appreciated.
Thanks a lot.

Assuming that in the class path, in the jar the directory starts with /json (/resource is a root directory), it could be as such:
URL url = getClass().getResource("/json");
Path path = Paths.get(url.toURI());
Files.walk(path, 5).forEach(p -> System.out.printf("- %s%n", p.toString()));
This uses a jar:file://... URL, and opens a virtual file system on it.
Inspect that the jar indeed uses that path.
Reading can be done as desired.
BufferedReader in = Files.newBufferedReader(p, StandardCharsets.UTF_8);

Firstly, remember that Jars are Zip files so you can't get an individual File out of it without unzipping it. Zip files don't exactly have directories, so it's not as simple as getting the children of a directory.
This was a bit of a difficult one but I too was curious, and after researching I have come up with the following.
Firstly, you could try putting the resources into a flat Zip file (resource/json/templates.zip) nested in the Jar, then loading all the resources from that zip file since you know all the zip entries will be the resources you want. This should work even in the IDE.
String path = "resource/json/templates.zip";
ZipInputStream zis = new ZipInputStream(getClass().getResourceAsStream(path));
for (ZipEntry ze = zis.getNextEntry(); ze != null; ze = zis.getNextEntry()) {
// 'zis' is the input stream and will yield an 'EOF' before the next entry
templateJson = (JSONObject) parser.parse(zis);
}
Alternatively, you could get the running Jar, iterate through its entries, and collect the ones that are children of resource/json/templates/ then get the streams from those entries. NOTE: This will only work when running the Jar, add a check to run something else while running in the IDE.
public void runOrSomething() throws IOException, URISyntaxException {
// ... other logic ...
final String path = "resource/json/templates/";
Predicate<JarEntry> pred = (j) -> !j.isDirectory() && j.getName().startsWith(path);
try (JarFile jar = new Test().getThisJar()) {
List<JarEntry> resources = getEntriesUnderPath(jar, pred);
for (JarEntry entry : resources) {
System.out.println(entry.getName());
try (InputStream is = jar.getInputStream(entry)) {
// JarEntry streams are closed when their JarFile is closed,
// so you must use them before closing 'jar'
templateJson = (JSONObject) parser.parse(is);
// ... other logic ...
}
}
}
}
// gets ALL the children, not just direct
// path should usually end in backslash
public static List<JarEntry> getEntriesUnderPath(JarFile jar, Predicate<JarEntry> pred)
{
List<JarEntry> list = new LinkedList<>();
Enumeration<JarEntry> entries = jar.entries();
// has to iterate through all the Jar entries
while (entries.hasMoreElements()) {
JarEntry entry = entries.nextElement();
if (pred.test(entry))
list.add(entry);
}
return list;
}
public JarFile getThisJar() throws IOException, URISyntaxException {
URL url = getClass().getProtectionDomain().getCodeSource().getLocation();
return new JarFile(new File(url.toURI()));
}
I hope this helps.

Getting strange structure file when zipping a directory using Java

I wanted to zip a directory with files and subdirectories in it. I did this and worked fine but I am getting and unusual and curious file structure (At least I see it that way).
This is the created file: When I click on it, I see an "empty" directory like this: but when I unzip this I see this file structure (Not all the names are exacly as they are showed in the image below):
|mantenimiento
|Carpeta_A
|File1.txt
|File2.txt
|Carpeta_B
|Sub_carpetaB
|SubfileB.txt
|Subfile1B.txt
|Subfile2B.txt
|File12.txt
My problem somehow is that the folder "mantenimiento" is where I am zippping from (the directory which I want to zip) and I dont want it to be there, so when I unzip the just created .zip file I want it with this file structure (which are the files and directories inside "mantenimiento" directory): and the other thing is when I click on the .zip file I want to see the files and directories just like the image showed above.
I dont know what's wrong with my code, I have searched but haven't found a reference to what my problem might be.
Here's my code:
private void zipFiles( List<File> files, String directory) throws IOException
{
ZipOutputStream zos = null;
ZipEntry zipEntry = null;
FileInputStream fin = null;
FileOutputStream fos = null;
BufferedInputStream in = null;
String zipFileName = getZipFileName();
try
{
fos = new FileOutputStream( File.separatorChar + zipFileName + EXTENSION );
zos = new ZipOutputStream(fos);
byte[] buf = new byte[1024];
int len;
for(File file : files)
{
zipEntry = new ZipEntry(file.toString());
fin = new FileInputStream(file);
in = new BufferedInputStream(fin);
zos.putNextEntry(zipEntry);
while ((len = in.read(buf)) >= 0)
{
zos.write(buf, 0, len);
}
}
}
catch(Exception e)
{
System.err.println("No fue posible zipear los archivos");
e.printStackTrace();
}
finally
{
in.close();
zos.closeEntry();
zos.close();
}
}
Hope you guys can give me a hint about what I am doing wrong or what I am missing.
Thanks a lot.
Btw, the directory i am giving to the method is never used. The other parameter i am giving is a list of files which contains all the files and directories from the C:\mantenimiento directory.

I once had a problem with windows and zip files, where the created zip did not contain the entries for the folders (i.e. /, /Carpeta_A etc) only the file entries. Try adding ZipEntries for the folders without streaming content.
But as alternative to the somewhat bulky Zip API of Java you could use Filesystem (since Java7) instead. The following example is for Java8 (lambda):
//Path pathToZip = Paths.get("path/to/your/folder");
//Path zipFile = Paths.get("file.zip");
public Path zipPath(Path pathToZip, Path zipFile) {
Map<String, String> env = new HashMap<String, String>() {{
put("create", "true");
}};
try (FileSystem zipFs = FileSystems.newFileSystem(URI.create("jar:" + zipFile.toUri()), env)) {
Path root = zipFs.getPath("/");
Files.walk(pathToZip).forEach(path -> zip(root, path));
}
}
private static void zip(final Path zipRoot, final Path currentPath) {
Path entryPath = zipRoot.resolve(currentPath.toString());
try {
Files.createDirectories(entryPath.getParent());
Files.copy(currentPath, entryPath);
} catch (IOException e) {
throw new RuntimeException(e);
}
}

Create JAR of the program itself

I have a program that needs to be able to create an executable JAR-file of itself, but I'm unfortunately having some trouble making it work. This is the method I'm currently using to create the JAR:
public static void createJar() throws IOException {
Manifest manifest = new Manifest();
manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0");
manifest.getMainAttributes().put(Attributes.Name.MAIN_CLASS, "JarTest");
JarOutputStream jos = null;
try {
String jarPath = System.getProperty("user.dir") + "/Test.jar";
jos = new JarOutputStream(new FileOutputStream(jarPath), manifest);
}
catch (IOException e) {e.printStackTrace();}
ArrayList<String> fileList = new ArrayList<String>();
String codeDir = System.getProperty("user.dir") + "/bin/jartest/";
Files.list(Paths.get(codeDir)).forEach(entry -> {
fileList.add(((Path)entry).toString());
});
int len = 0;
byte[] buffer = new byte[1024];
for(String file : fileList ) {
//create JarEntry
JarEntry je = new JarEntry(file);
je.setComment("Creating Jar");
je.setTime(Calendar.getInstance().getTimeInMillis());
System.out.println(je);
jos.putNextEntry(je);
//write the bytes of file into jar
InputStream is = new BufferedInputStream(new FileInputStream(file));
while((len = is.read(buffer, 0, buffer.length)) != -1)
jos.write(buffer, 0, len);
is.close();
jos.closeEntry();
System.out.println("Done");
}
jos.close();
}
When I execute this no errors happen and I do get a JAR file called "Test.jar" generated in my Eclipse project folder. But when I open the JAR the .class files are not there, instead I see this:
I know that it's finding the .class files since the line System.out.println(je); successfully prints out the absolute path of each of them, so why aren't they getting put into the JAR?

It solved itself when I changed these two lines:
String jarPath = System.getProperty("user.dir") + "/Test.jar";
String codeDir = System.getProperty("user.dir") + "/bin/jartest/";
To these:
String jarPath = "Test.jar";
String codeDir = "bin/jartest/";
I can now see the .class files inside the JAR.

Scanner and Multithreading issues?

I have following code to read entire file data:
calling method(String zipFile){
ZipInputStream zis =
new ZipInputStream(new FileInputStream(zipFile));
//get the zipped file list entry
ZipEntry ze = zis.getNextEntry();
while (ze != null) {
String fileName = ze.getName();
File newFile =
new File(Constants.OUTPUT_FOLDER + File.separator +
fileName);
if (ze.isDirectory()) {
new File(newFile.getParent()).mkdirs();
} else {
new File(newFile.getParent()).mkdirs();
createBlobDomain(zFile,ze);
}
}
ze = zis.getNextEntry();
}
zis.closeEntry();
zis.close();
}
public String method(ZipFile zf, ZipEntry ze){
scan = new Scanner(zf.getInputStream(ze));
if(scan.hasNext())
fullText = scan.useDelimiter("\\A").next();
return fullText;
}
Please ignore it from compilation perspective as i removed some code not really relevant here. It works fine when run from the webapp as a single instance. But it i run it from two different browsers at the same time then i hit below exception. Please advise what could be going wrong and how to fix it.
java.util.InputMismatchException
at java.util.Scanner.throwFor(Scanner.java:840)
at java.util.Scanner.next(Scanner.java:1347)

I believe the line scan = new Scanner(zf.getInputStream(ze)); is creating the problem. What I understand from you code is scan is an instance variable which you are assigning a new Scanner with every thread. I would suggest to make it as a local variable in your method. Correct me If I misunderstood anything.
Scanner scan = new Scanner(zf.getInputStream(ze))

It looks to me that what you want to do is to copy the contents of a zip into a given folder.
Provided you use Java 7+, it's actually pretty simple to do that; this code uses java7-fs-more to help you do the job:
public static void extractZip(final String zipfile, final String dstdir)
throws IOException
{
final Map<String, ?> env = Collections.singletonMap("readonly", "true);
final Path path = Paths.get(zipfile);
final URI uri = URI.create("jar:" + path.toUri());
try (
final FileSystem zipfs = FileSystems.newFileSystem(uri, env);
) {
MoreFiles.copyRecursive(zipfs.getPath("/"), Paths.get(dstdir),
RecursionMode.FAIL_FAST);
}
}