前段时间我在寻找一个Java中可嵌入的分布式版本控制系统,我认为我在JGit中找到了它,这是git的纯Java实现。然而,缺少示例代码或教程。
我该如何使用JGit检索某个文件的HEAD版本(就像svn cat
或hg cat
一样)?
我想这涉及一些rev-tree-walking,并正在寻找代码示例。
前段时间我在寻找一个Java中可嵌入的分布式版本控制系统,我认为我在JGit中找到了它,这是git的纯Java实现。然而,缺少示例代码或教程。
我该如何使用JGit检索某个文件的HEAD版本(就像svn cat
或hg cat
一样)?
我想这涉及一些rev-tree-walking,并正在寻找代码示例。
很遗憾,Thilo的答案在最新的JGit API中不起作用。这是我找到的解决方法:
File repoDir = new File("test-git");
// open the repository
Repository repository = new Repository(repoDir);
// find the HEAD
ObjectId lastCommitId = repository.resolve(Constants.HEAD);
// now we have to get the commit
RevWalk revWalk = new RevWalk(repository);
RevCommit commit = revWalk.parseCommit(lastCommitId);
// and using commit's tree find the path
RevTree tree = commit.getTree();
TreeWalk treeWalk = new TreeWalk(repository);
treeWalk.addTree(tree);
treeWalk.setRecursive(true);
treeWalk.setFilter(PathFilter.create(path));
if (!treeWalk.next()) {
return null;
}
ObjectId objectId = treeWalk.getObjectId(0);
ObjectLoader loader = repository.open(objectId);
// and then one can use either
InputStream in = loader.openStream()
// or
loader.copyTo(out)
我希望它更简单。
TreeWalk
可以遍历多个树(通过多次调用addTree
)。在这种情况下,您可以使用getObjectId(N)
从树N中获取对象ID(根据树的不同可能相同或不同)。 - robinstTreeWalk.forPath
来简化此过程。 - robinstloader
的输出保存到一个变量中? - Evgenij Reznik这是 @morisil 的答案的一个更简单的版本,使用了 @directed laugh 的一些概念,并使用 JGit 2.2.0 进行了测试:
private String fetchBlob(String revSpec, String path) throws MissingObjectException, IncorrectObjectTypeException,
IOException {
// Resolve the revision specification
final ObjectId id = this.repo.resolve(revSpec);
// Makes it simpler to release the allocated resources in one go
ObjectReader reader = this.repo.newObjectReader();
try {
// Get the commit object for that revision
RevWalk walk = new RevWalk(reader);
RevCommit commit = walk.parseCommit(id);
// Get the revision's file tree
RevTree tree = commit.getTree();
// .. and narrow it down to the single file's path
TreeWalk treewalk = TreeWalk.forPath(reader, path, tree);
if (treewalk != null) {
// use the blob id to read the file's data
byte[] data = reader.open(treewalk.getObjectId(0)).getBytes();
return new String(data, "utf-8");
} else {
return "";
}
} finally {
reader.close();
}
}
repo
是在其他答案中创建的Repository对象。
walk
和treeWalk
上的release
方法。为了只需要执行一次,可以调用ObjectReader reader = repo.newObjectReader()
并将其传递给Revwalk和Treewalk,而不是仓库。然后在finally块中调用reader.release()
。 - robinstnewObjectReader
的位置上移,并使用new RevWalk(reader)
代替。 - robinstthis.repo.open
也应该被替换为 reader.open
。 - robinst我按照@Thilo和@morisil的答案进行了操作,这个方法兼容JGit 1.2.0:
File repoDir = new File("test-git/.git");
// open the repository
Repository repo = new Repository(repoDir);
// find the HEAD
Commit head = repo.mapCommit(Constants.HEAD);
// retrieve the tree in HEAD
Tree tree = head.getTree();
// 1.2.0 api version here
// find a file (as a TreeEntry, which contains the blob object id)
TreeWalk treewalk = TreeWalk.forPath(repo, "b/test.txt", tree);
// use the blob id to read the file's data
byte[] data = repo.open(treewalk.getObjectId(0)).getBytes();
我没测试Java版本,但应该可以正常工作。它从...翻译。(.getBytes (.open repo (.getObjectId (TreeWalk/forPath repo "b/test.txt" tree) 0)))
在Clojure中(遵循与前面部分相同的设置),这确实起作用。
FileOutputStream fileOS = new FileOutputStream(path); if (treewalk != null){repo.open(treewalk.getObjectId(0)).copyTo(fileOS);}
然后 fileOS.close;
。 - Mark Mikofski我自己找到了答案。这个API属于比较底层的,但是也不太难:
File repoDir = new File("test-git/.git");
// open the repository
Repository repo = new Repository(repoDir);
// find the HEAD
Commit head = repo.mapCommit(Constants.HEAD);
// retrieve the tree in HEAD
Tree tree = head.getTree();
// find a file (as a TreeEntry, which contains the blob object id)
TreeEntry entry = tree.findBlobMember("b/test.txt");
// use the blob id to read the file's data
byte[] data = repo.openBlob(entry.getId()).getBytes();
Repository repo = new FileRepository("/repos/project/.git");
String content = BlobUtils.getHeadContent(repo, "src/Buffer.java");
获取分支上文件的内容
Repository repo = new FileRepository("/repos/project/.git");
String content = BlobUtils.getContent(repo, "master", "src/Buffer.java");
比较两个文件的差异
Repository repo = new FileRepository("/repos/project/.git");
ObjectId current = BlobUtils.getId(repo, "master", "Main.java");
ObjectId previous = BlobUtils.getId(repo, "master~1", "Main.java");
Collection<Edit> edit = BlobUtils.diff(repo, previous, current);
public String readFile(RevCommit commit, String filepath) throws IOException {
try (TreeWalk walk = TreeWalk.forPath(repo, filepath, commit.getTree())) {
if (walk != null) {
byte[] bytes = repo.open(walk.getObjectId(0)).getBytes();
return new String(bytes, StandardCharsets.UTF_8);
} else {
throw new IllegalArgumentException("No path found.");
}
}
}
例如:
ObjectId head = repo.resolve(Constants.HEAD);
RevCommit last = repo.parseCommit(head);
readFile(last, "docs/README.md")