clone git repositories

src/de/uni_passau/fim/seibt/gitwrapper/repo/Git.java

+package de.uni_passau.fim.seibt.gitwrapper.repo;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Optional;
+import java.util.Scanner;
+import java.util.function.Function;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.apache.commons.io.IOUtils;
+
+public class Git {
+
+    public static final int EXIT_SUCCESS = 0;
+    public static final int EXIT_FAIL = 1;
+
+    private static final Logger LOG = Logger.getLogger(Git.class.getCanonicalName());
+    private static final Pattern CLONING_INTO = Pattern.compile("Cloning into '(.*)'\\.\\.\\.");
+
+    private class ExecRes {
+        private int code;
+        private String output;
+    }
+
+    private String git;
+
+    public Git(String git) {
+        this.git = git;
+    }
+
+    public Optional<Repository> clone(File parentDir, String url) {
+        LOG.fine(() -> String.format("Cloning '%s'.", url));
+
+        Optional<ExecRes> res = exec(parentDir, "clone", url);
+        Function<ExecRes, Repository> toRepo = execRes -> {
+
+            if (execRes.code != EXIT_SUCCESS) {
+                // the repo may already exist (resulting in code 128) - pull it? delete it?
+                LOG.warning(() -> String.format("Exit code %d indicates failure while cloning '%s'.", execRes.code, url));
+                return null;
+            }
+
+            Scanner sc = new Scanner(execRes.output);
+
+            if (!sc.hasNextLine()) {
+                LOG.warning(() -> String.format("No output while cloning '%s'.", url));
+                return null;
+            }
+
+            Matcher matcher = CLONING_INTO.matcher(sc.nextLine());
+
+            if (!matcher.find()) {
+                LOG.warning(() -> String.format("Unexpected output while cloning '%s'", url));
+                return null;
+            }
+
+            String name = matcher.group(1);
+            File repoDir = new File(parentDir, name);
+
+            LOG.fine(() -> "Cloned " + url + " into " + repoDir.getAbsolutePath());
+
+            return new Repository(this, url, repoDir);
+        };
+
+        return res.map(toRepo);
+    }
+
+    public Optional<ExecRes> exec(File workingDirectory, String... parameters) {
+        ProcessBuilder b = new ProcessBuilder();
+        String[] cmdArray = new String[parameters.length + 1];
+
+        cmdArray[0] = git;
+        System.arraycopy(parameters, 0, cmdArray, 1, parameters.length);
+
+        b.command(cmdArray);
+        b.directory(workingDirectory);
+        b.redirectErrorStream(true);
+
+        String cmd = String.join(" ", b.command());
+
+        LOG.fine(() -> String.format("Executing '%s'.", cmd));
+
+        try {
+            ExecRes res = new ExecRes();
+            Process p = b.start();
+
+            res.output = IOUtils.toString(p.getInputStream());
+            res.code = p.waitFor();
+
+            LOG.fine(() -> String.format("Execution of '%s' returned exit code %d.", cmd, res.code));
+
+            return Optional.of(res);
+        } catch (IOException | InterruptedException e) {
+            LOG.log(Level.SEVERE, e, () -> String.format("Exception executing '%s'.", cmd));
+            return Optional.empty();
+        }
+    }
+}

src/de/uni_passau/fim/seibt/gitwrapper/repo/Repository.java

+package de.uni_passau.fim.seibt.gitwrapper.repo;
+
+import java.io.File;
+
+public class Repository {
+
+    private Git git;
+
+    private String url;
+    private File dir;
+
+    Repository(Git git, String url, File dir) {
+        this.git = git;
+        this.url = url;
+        this.dir = dir;
+    }
+
+    @Override
+    public String toString() {
+        return String.format("Repository{url=%s, dir=%s}", url, dir);
+    }
+}