Mega Code Archive
Determine whether a file is a JAR File
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import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.ZipFile;
public class Main {
/**
* Determine whether a file is a JAR File.
*/
public static boolean isJarFile(File file) throws IOException {
if (!isZipFile(file)) {
return false;
}
ZipFile zip = new ZipFile(file);
boolean manifest = zip.getEntry("META-INF/MANIFEST.MF") != null;
zip.close();
return manifest;
}
/**
* Determine whether a file is a ZIP File.
*/
public static boolean isZipFile(File file) throws IOException {
if(file.isDirectory()) {
return false;
}
if(!file.canRead()) {
throw new IOException("Cannot read file "+file.getAbsolutePath());
}
if(file.length() < 4) {
return false;
}
DataInputStream in = new DataInputStream(new BufferedInputStream(new FileInputStream(file)));
int test = in.readInt();
in.close();
return test == 0x504b0304;
}
}
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