Merge pull request 'Add checkstyle linter for java' (!27) from ci/java-pipes into main

Reviewed-on: #27

.gitea/workflows/ci.yml

@@ -4,6 +4,39 @@ on:
   pull_request:
 
 jobs:
+  checkstyle:
+    name: "Checkstyle Main"
+    runs-on: "vps-4"
+    container:
+      image: "cimg/openjdk:22.0-node"
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v3
+      - name: Setup Java 22
+        uses: actions/setup-java@v3
+        with:
+          distribution: "temurin"
+          java-version: "22"
+
+      - uses: actions/cache@v3
+        working-directory: ./backend
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+      - name: "Prepare Gradle"
+        working-directory: ./backend
+        run: gradle clean
+      - name: "Check"
+        working-directory: ./backend
+        run: gradle checkstyleMain
+      - name: "Stop Gradle"
+        working-directory: ./backend
+        run: gradle --stop
+
   eslint:
     name: eslint
     runs-on: vps-4

backend/build.gradle.kts

@@ -2,6 +2,21 @@ plugins {
     java
     id("org.springframework.boot") version "3.3.3"
     id("io.spring.dependency-management") version "1.1.6"
+    id("checkstyle")
+}
+
+checkstyle {
+    configFile = file("$rootDir/config/checkstyle/checkstyle.xml")
+}
+
+tasks.withType<Checkstyle> {
+    reports {
+        // Disable HTML report
+        html.required.set(false)
+
+        // Disable XML report
+        xml.required.set(false)
+    }
 }
 
 group = "de.szut"

backend/config/checkstyle/checkstyle.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0"?>
+<!DOCTYPE module PUBLIC
+        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+        "https://checkstyle.org/dtds/configuration_1_3.dtd"
+        >
+<module name="Checker">
+    <property name="severity" value="error"/>
+    <property name="tabWidth" value="4"/>
+
+    <module name="LineLength">
+        <property name="max" value="500"/>
+    </module>
+    <module name="FileTabCharacter">
+        <property name="eachLine" value="true"/>
+    </module>
+
+    <module name="NewlineAtEndOfFile"/>
+</module>