Get a JarFile from a JarEntry

Question

My current task is to iterate a .jar to see if it has .jars inside. Then I have to get those .jars and check certain file in each one.To do that, I am using JarFile to get the JarEntries. The problem is, How do I do to get again the JarFile from the current Jar Entry?. Is it possible?

Jar:
 Jar1:   
   /META-INF/source/file1.txt
 Jar2: 
   /META-INF/source/file1.txt

Here is my current code:

 public static void main(String[] args) throws IOException,   URISyntaxException {

    String dir = Paths.get(".").toAbsolutePath().normalize().toString() + "/target";
    Collection<String> jarBuildList = JarFinder.getJars(dir);
    for(String buildJar : jarBuildList){

        File file = new File(buildJar);
        JarFile buildJarFile = new JarFile(file);

             Enumeration<JarEntry> entries = buildJarFile.entries();
             while (entries.hasMoreElements()) {
                JarEntry jarEntry = entries.nextElement();
                if (jarEntry.getName().contains(".jar")){
                      //Having the JarEntry, enter to that jar javaEntry and get a file1.txt
                }                       
             }              
        }

    }
}

extract the jar file inside, with this: http://stackoverflow.com/questions/1529611/how-to-write-a-java-program-which-can-extract-a-jar-file-and-store-its-data-in-s and do it again — guillaume girod-vitouchkina, Dec 11 '15 at 23:25
Why not convert it to a zip, extract the files in there, if those files are a jar, repeat. — Andre, Dec 11 '15 at 23:25

score 0 · Answer 1 · answered Dec 12 '15 at 01:25

How do I do to get again the JarFile from the current Jar Entry?. Is it possible?

Not directly, no. Your alternatives are:

copy the content of the entry to a file in the file system and use JarFile to open that, or
use the JarInputStream API.

FWIW, the reason that JarFile only works on files in the file system is that its implementation is a native library which uses native code to open and read the source file. It was done this way (I think) because loading from JAR / ZIP files has to work before the JVM is fully bootstrapped. Then the API became frozen ... for the normal reasons.

Get a JarFile from a JarEntry

1 Answers1