Add script to publish Javadoc to GH Pages

The Javadocs are build via Gradle and pushed to the "gh-pages" branch
of this repository. The script is executed by Travis CI.

The variable $TRAVIS_BUILD_DIR is set by Travis CI, while $GIT_REPO_URL
must be provided as secure environment variable (via Travis CI).

No documentation is generated for pull requests, and to avoid that the
docs are generated four times, for each build target once, it is
further restricted to the "oraclejdk8" builds.

Author: dexX7

.travis.yml

@@ -23,3 +23,12 @@ install:
 
 script:
   - ./gradlew clean test
+
+deploy:
+  provider: script
+  script: scripts/deploy_gh-pages.sh
+  skip_cleanup: true
+  on:
+    branch: master
+    jdk: oraclejdk8
+    condition: "$TRAVIS_PULL_REQUEST != true"

README.adoc

@@ -4,6 +4,8 @@ image:https://travis-ci.org/dexX7/java-libbitcoinconsensus.svg["Build Status", l
 
 A https://github.com/java-native-access/jna[JNA] binding and Java wrapper for https://github.com/bitcoin/bitcoin/blob/master/doc/shared-libraries.md#bitcoinconsensus[libbitcoinconsensus].
 
+See the http://dexx7.github.io/java-libbitcoinconsensus/[Javadoc] for an overview of this project.
+
 WARNING: This software is EXPERIMENTAL software. USE AT YOUR OWN RISK.
 
 == Setup

scripts/README.adoc

@@ -0,0 +1,7 @@
+= java-libbitcoinconsensus: scripts
+
+This directory contains scripts and helpers.
+
+== deploy_gh-pages.sh
+
+A script used by Travis CI to generate and deploy the http://dexx7.github.io/java-libbitcoinconsensus/[Javadoc] to https://github.com/dexX7/java-libbitcoinconsensus/tree/gh-pages/[GitHub Pages].

scripts/deploy_gh-pages.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+set -e
+
+echo "Deploying JavaDoc to GitHub Pages.."
+
+# Commit hash of the main repository
+GIT_COMMIT=$(git rev-parse --short HEAD)
+
+# Base dir of the project
+BUILD_DIR=$TRAVIS_BUILD_DIR
+
+# The destination of the documentation
+DOCS_DIR=$BUILD_DIR/build/docs/javadoc
+
+# Generate the JavaDoc
+$BUILD_DIR/gradlew --quiet clean javadoc
+
+# Setup a new repository locally and commit the documentation
+cd $DOCS_DIR
+git init
+git config user.name "Travis CI"
+git config user.email "ci@bitwatch.co"
+git add .
+git commit -m "Deploy Javadoc for commit: ${GIT_COMMIT}"
+
+# Force push to the remote gh-pages branch
+#
+# Note: the GIT_REPO_URL should contain the remote destination, including
+# OAuth access token, such as: https://1234567@github.com/user/repo.git
+#
+# The actual value is provided via Travis CI as secure environment variable:
+# http://docs.travis-ci.com/user/encryption-keys/
+# http://docs.travis-ci.com/user/environment-variables/#Defining-Variables-in-Repository-Settings
+#
+# Write access for the repository is required, and the minimum scope of
+# the access token is "repo". For more information about API tokens see:
+# https://help.github.com/articles/creating-an-access-token-for-command-line-use/
+#
+# To avoid leaking credentials, the push is silenced.
+git push --force --quiet $GIT_REPO_URL master:gh-pages > /dev/null 2>&1