com.buildautomation.jgit.api.ShowBlame.java Source code

Introduction

Here is the source code for com.buildautomation.jgit.api.ShowBlame.java

Source

package com.buildautomation.jgit.api;

/*
Copyright 2013, 2014 Dominik Stadler
    
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
    
  http://www.apache.org/licenses/LICENSE-2.0
    
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import org.apache.commons.io.IOUtils;
import org.eclipse.jgit.api.BlameCommand;
import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.blame.BlameResult;
import org.eclipse.jgit.lib.ObjectId;
import org.eclipse.jgit.lib.ObjectLoader;
import org.eclipse.jgit.lib.Repository;
import org.eclipse.jgit.revwalk.RevCommit;
import org.eclipse.jgit.revwalk.RevTree;
import org.eclipse.jgit.revwalk.RevWalk;
import org.eclipse.jgit.treewalk.TreeWalk;
import org.eclipse.jgit.treewalk.filter.PathFilter;

/**
 * Simple snippet which shows how to get a diff showing who
 * changed which line in a file
 *
 * @author dominik.stadler at gmx.at
 */
public class ShowBlame {

    public static void showBlame() throws IOException, GitAPIException {
        // prepare a new test-repository
        try (Repository repository = CookbookHelper.openJGitCookbookRepository()) {
            BlameCommand blamer = new BlameCommand(repository);
            ObjectId commitID = repository.resolve("HEAD");
            blamer.setStartCommit(commitID);
            blamer.setFilePath("README.md");
            BlameResult blame = blamer.call();

            // read the number of lines from the commit to not look at changes in the working copy
            int lines = countFiles(repository, commitID, "README.md");
            for (int i = 0; i < lines; i++) {
                RevCommit commit = blame.getSourceCommit(i);
                System.out.println("Line: " + i + ": " + commit);
            }

            System.out.println("Displayed commits responsible for " + lines + " lines of README.md");
        }
    }

    private static int countFiles(Repository repository, ObjectId commitID, String name) throws IOException {
        try (RevWalk revWalk = new RevWalk(repository)) {
            RevCommit commit = revWalk.parseCommit(commitID);
            RevTree tree = commit.getTree();
            System.out.println("Having tree: " + tree);

            // now try to find a specific file
            try (TreeWalk treeWalk = new TreeWalk(repository)) {
                treeWalk.addTree(tree);
                treeWalk.setRecursive(true);
                treeWalk.setFilter(PathFilter.create(name));
                if (!treeWalk.next()) {
                    throw new IllegalStateException("Did not find expected file 'README.md'");
                }

                ObjectId objectId = treeWalk.getObjectId(0);
                ObjectLoader loader = repository.open(objectId);

                ByteArrayOutputStream stream = new ByteArrayOutputStream();
                // and then one can the loader to read the file
                loader.copyTo(stream);

                revWalk.dispose();

                return IOUtils.readLines(new ByteArrayInputStream(stream.toByteArray())).size();
            }
        }
    }
}