DiffJars.java

package jane.tool;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.zip.Deflater;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
import jane.core.Util;

/**
 * 对比jar1和jar2两个文件,生成一个新的jar文件,其中包含jar2中有但jar1中没有,以及jar2中有jar1里不同内容但文件路径名相同的文件
 * 一般用于给出原版jar和新版jar,生成新版的补丁jar,空目录会被忽略
 * 也可用于zip格式
 */
public final class DiffJars
{
	private final MessageDigest md5;

	public DiffJars() throws NoSuchAlgorithmException
	{
		md5 = MessageDigest.getInstance("MD5");
	}

	public byte[] getMd5(byte[] data, int pos, int len)
	{
		md5.reset();
		md5.update(data, pos, len);
		return md5.digest();
	}

	public static void ensurePath(ZipOutputStream zos, HashSet<String> pathes, String path) throws IOException
	{
		int p = path.lastIndexOf('/');
		if(p < 0 || pathes.contains(path.substring(0, p + 1)))
			return;
		for(p = 0;;)
		{
			p = path.indexOf('/', p);
			if(p < 0) break;
			String subPath = path.substring(0, p + 1);
			if(!pathes.contains(subPath))
			{
				pathes.add(subPath);
				zos.putNextEntry(new ZipEntry(subPath));
				zos.closeEntry();
			}
		}
	}

	public int diffJars(InputStream isJar1, InputStream isJar2, OutputStream osJar, PrintStream osLog) throws IOException
	{
		int count = 0;
		HashMap<String, byte[]> jar1Md5s = new HashMap<>();
		HashSet<String> pathes = new HashSet<>();
		byte[] buf = new byte[0x10000];

		try(ZipInputStream zis = new ZipInputStream(new BufferedInputStream(isJar1)))
		{
			for(ZipEntry ze; (ze = zis.getNextEntry()) != null;)
			{
				if(ze.isDirectory()) continue;
				int len = (int)ze.getSize();
				if(len < 0) continue;
				if(len > buf.length)
					buf = new byte[len];
				Util.readStream(zis, ze.getName(), buf, len);
				jar1Md5s.put(ze.getName(), getMd5(buf, 0, len));
			}
		}

		try(ZipInputStream zis = new ZipInputStream(new BufferedInputStream(isJar2)))
		{
			try(ZipOutputStream zos = new ZipOutputStream(new BufferedOutputStream(osJar)))
			{
				zos.setMethod(ZipOutputStream.DEFLATED);
				zos.setLevel(Deflater.BEST_COMPRESSION);
				for(ZipEntry ze; (ze = zis.getNextEntry()) != null;)
				{
					if(ze.isDirectory()) continue;
					int len = (int)ze.getSize();
					if(len > buf.length)
						buf = new byte[len];
					String name = ze.getName();
					Util.readStream(zis, name, buf, len);
					if(Arrays.equals(getMd5(buf, 0, len), jar1Md5s.get(name)))
						continue;
					if(osLog != null)
						osLog.println(name);
					ensurePath(zos, pathes, name);
					zos.putNextEntry(new ZipEntry(name));
					zos.write(buf, 0, len);
					zos.closeEntry();
					++count;
				}
			}
		}

		return count;
	}

	@SuppressWarnings("resource")
	public static void main(String[] args) throws Exception
	{
		if(args.length < 3)
		{
			System.err.println("USAGE: java -cp jane-core.jar jane.tool.DiffJars <file1.jar> <file2.jar> <diff.jar>");
			return;
		}

		System.out.println(String.format("%s -> %s = %s ... ", args[0], args[1], args[2]));
		int count = new DiffJars().diffJars(new FileInputStream(args[0]), new FileInputStream(args[1]), new FileOutputStream(args[2]), System.out);
		System.out.println(String.format("done! (%d files)", count));
	}
}