Manipulating Java archives
Here I want you to present two short code snippets, showing how you can work with Java
archives (jar, war and ear files).
For these examples, the XML manipulation library JDom is used.
TODO
Reading Java archives
blabla
(the code can be downloaded here):
package de.kksoftware.demo.xml;
import java.util.*;
import java.io.*;
import java.util.jar.*;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.input.SAXBuilder;
public class ReadJarFile {
public static void main(String[] args) throws Exception {
// open an EJB jar file
JarFile oJar = new JarFile(new File("GeneralKey.jar"));
// print out all entries of the archive
Enumeration oEntries = oJar.entries();
while (oEntries.hasMoreElements()) {
JarEntry oEntry = (JarEntry)oEntries.nextElement();
System.out.println(".. "+oEntry.getName());
}
// look for the ejb-jar.xml entry
JarEntry oEJBJarEntry = oJar.getJarEntry("META-INF/ejb-jar.xml");
// read the deployment descriptor into JDom
InputStream oInStream = oJar.getInputStream(oEJBJarEntry);
SAXBuilder oBuilder = new SAXBuilder();
Document oEjbDoc = oBuilder.build(oInStream);
oInStream.close();
Element oRoot = oEjbDoc.getRootElement();
System.out.println("The root element of ejb-jar.xml is "+oRoot.getName());
// do other XML stuff with the deployment descriptor
}
}
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Writing Java archives
blabla
(the code can be downloaded here):
package de.kksoftware.demo.xml;
import java.util.*;
import java.io.*;
import java.util.jar.*;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.output.XMLOutputter;
public class WriteJarFile {
public static void main(String[] args) throws Exception {
// open an EJB jar file
JarFile oJar = new JarFile(new File("GeneralKey.jar"));
// create a stream to the new archive
OutputStream oOut = new FileOutputStream(new File("MyKey.jar"));
JarOutputStream oJarOut = new JarOutputStream(oOut);
// copy all entries of the archive except the deployment descriptor
int iSize = 0;
byte[] oBuffer = new byte[1024];
Enumeration oEntries = oJar.entries();
while (oEntries.hasMoreElements()) {
JarEntry oEntry = (JarEntry)oEntries.nextElement();
if (!oEntry.getName().equals("META-INF/ejb-jar.xml")){
System.out.println ("copying jar entry "+oEntry.getName()+" ...");
oJarOut.putNextEntry(oEntry);
InputStream oJarInStream = oJar.getInputStream(oEntry);
while ((iSize = oJarInStream.read(oBuffer))!=-1){
oJarOut.write(oBuffer, 0, iSize);
}
oJarInStream.close();
}
}
// create my own descriptor
Element oRoot = new Element("myejb-jar");
Document oDoc = new Document(oRoot);
Element oNode = new Element("mynode");
oRoot.addContent(oNode);
// write it instead of the original one
System.out.println ("writing myejb-jar.xml");
oJarOut.putNextEntry(new JarEntry("META-INF/myejb-jar.xml"));
XMLOutputter oXMLOut = new XMLOutputter(" ", true);
oXMLOut.output(oDoc, oJarOut);
// all done
oJarOut.close();
oOut.close();
}
}
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