Merge pull request #8 from weiguoz/ci

speed up CI

Author: weiguoz

.travis.yml

@@ -1,2 +1,14 @@
 language: java
-script: mvn clean verify
+sudo: false
+cache:
+  directories:
+    - $HOME/.m2
+
+env:
+  - JDK=oraclejdk8
+dist: trusty
+before_script:
+  - jdk_switcher use $JDK
+
+script:
+  - mvn clean verify --batch-mode --errors --fail-at-end --show-version -DinstallAtEnd=true

pom.xml

@@ -16,6 +16,8 @@
         <grpc.version>1.25.0</grpc.version>
         <junit.version>4.12</junit.version>
         <protoc.version>3.10.0</protoc.version>
+        <maven.compiler.target>1.8</maven.compiler.target>
+        <maven.compiler.source>1.8</maven.compiler.source>
     </properties>
     <dependencies>
         <dependency>