JarPatcher.java

package info.mineshafter.util;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

public class JarPatcher {
	private Map<String, byte[]> entries;

	public JarPatcher(File jarFile) {
		try {
			init(new FileInputStream(jarFile));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public JarPatcher(InputStream jarStream) {
		init(jarStream);
	}

	public JarPatcher(byte[] jarData) {
		init(new ByteArrayInputStream(jarData));
	}

	private void init(InputStream jarStream) {
		entries = new HashMap<String, byte[]>();

		try {
			ZipEntry entry;
			ZipInputStream jarIn = new ZipInputStream(jarStream);

			while ((entry = jarIn.getNextEntry()) != null) {
				String name = entry.getName();

				entries.put(name, Streams.toByteArray(jarIn));
			}

			jarIn.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public void setEntry(String name, byte[] data) {
		entries.put(name, data);
	}

	public void removeEntry(String name) {
		entries.remove(name);
	}
        
        public byte[] getEntry(String name){
            return entries.get(name);
        }
        
	public Collection<String> getEntries() {
		return new HashSet<String>(entries.keySet());
	}

	public void write(File destination) {
		try {
			write(new FileOutputStream(destination));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
	}

	public void write(OutputStream destination) {
		ZipOutputStream out = new ZipOutputStream(destination);

		try {
			for (String name : entries.keySet()) {
				ZipEntry entry = new ZipEntry(name);
				byte[] blob = entries.get(name);

				out.putNextEntry(entry);

				out.write(blob);
				out.flush();
			}

			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}