本文来自：
杨周 极狐GitLab 高级解决方案架构师
代码越写越规范是优秀开发者的成长之路，但很多人对老项目感到有心无力，因为太不规范了，所有人停下来一起修复也要花费很长时间，而且一次改动太多难以确保可靠性，怎么办？
有的语言可以借助 Git diff 把本次修改的代码挑出来，实现增量扫描，但 Java 很难这么做。
有的人在持续集成里配置了规范扫描工具，但报错之后需要在成千上万行 log 里查找，降低了研发效率。
Checkstyle 是业界知名的开源扫描工具，可扫描 Sun、Google 等代码规范，提供Maven、Gradle 插件。本文以 Java 项目配置 Checkstyle 扫描工具为例，分享消灭这些问题的办法：
1. 将代码规范问题显示在「合并请求页面」，大幅度提高研发效率；
2. 增量代码规范报告。
下文分别介绍「Java Maven 项目」和「Java Gradle 项目」的配置方法。
通过极狐GitLab CI 平滑落地 Java 增量代码规范Checkstyle Maven
在项目中引入 Checkstyle 插件，并下载代码规范：
$ vi pom.xml
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-checkstyle-plugin</artifactId>
<version>3.2.0</version>
<configuration>
<encoding>UTF-8</encoding>
<consoleOutput>true</consoleOutput>
<failsOnError>true</failsOnError>
<violationSeverity>warning</violationSeverity>
<configLocation>config/checkstyle/checkstyle.xml</configLocation>
</configuration>
</plugin>
$ mkdir -p config/checkstyle/
$ wget https://raw.githubusercontent.com/checkstyle/checkstyle/checkstyle-9.3/src/main/resources/google_checks.xml -O config/checkstyle/checkstyle.xml执行全量扫描命令，查看效果：
$ ./mvnw checkstyle:check
[WARN] Demo.java:6:1: 缺少 Javadoc 。 [MissingJavadocType]
[WARN] Demo.java:9:1: 行内含有制表符 tab 。 [FileTabCharacter]
[WARN] Demo.java:9:9: 'method def modifier' 缩进了8个缩进符，应为2个。 [Indentation]在极狐GitLab 持续集成中执行强制扫描：
$ vi .gitlab-ci.yml
checkstyle:
script:
- ./mvnw checkstyle:check
当扫描工具报错，持续集成退出，想看代码规范问题，需要到 log 中查找。很多持续集成产品只做到了这一步，但这降低了开发效率，因此极狐GitLab 更进一步——采集「代码质量报告」。
在项目中引入 violations-maven-plugin，它会将 Checkstyle 报告转换成极狐GitLab 标准格式。
$ vi pom.xml
<plugin>
<groupId>se.bjurr.violations</groupId>
<artifactId>violations-maven-plugin</artifactId>
<version>1.50.4</version>
<executions>
<execution>
<phase>validate</phase>
<goals>
<goal>violations</goal>
</goals>
<configuration>
<!-- Optional config -->
<!-- 0 is disabled -->
<maxReporterColumnWidth>0</maxReporterColumnWidth>
<maxRuleColumnWidth>0</maxRuleColumnWidth>
<maxSeverityColumnWidth>0</maxSeverityColumnWidth>
<maxLineColumnWidth>0</maxLineColumnWidth>
<maxMessageColumnWidth>30</maxMessageColumnWidth>
<!-- Will create a CodeClimate JSON report. -->
<codeClimateFile>gl-code-quality-report.json</codeClimateFile>
<!-- Global configuration, remove if you dont want to report violations
for the entire repo. -->
<!-- INFO, WARN or ERROR -->
<minSeverity>INFO</minSeverity>
<!-- PER_FILE_COMPACT, COMPACT or VERBOSE -->
<detailLevel>VERBOSE</detailLevel>
<!-- Will fail the build if total number of found violations is higher -->
<maxViolations>99999999</maxViolations>
<!-- Will print violations found in diff -->
<printViolations>true</printViolations>
<!-- Diff configuration, remove if you dont want to report violations
for files changed between specific revisions. -->
<!-- Can be empty (ignored), Git-commit or any Git-reference -->
<diffFrom></diffFrom>
<!-- Same as above -->
<diffTo></diffTo>
<!-- INFO, WARN or ERROR -->
<diffMinSeverity>INFO</diffMinSeverity>
<!-- PER_FILE_COMPACT, COMPACT or VERBOSE -->
<diffDetailLevel>VERBOSE</diffDetailLevel>
<!-- Will fail the build if number of violations, in the diff within
from/to, is higher -->
<diffMaxViolations>99</diffMaxViolations>
<!-- Will print violations found in diff -->
<diffPrintViolations>true</diffPrintViolations>
<!-- Where to look for Git -->
<gitRepo>.</gitRepo>
<!-- This is mandatory regardless of if you want to report violations
between revisions or the entire repo. -->
<violations>
<violation>
<parser>CHECKSTYLE</parser>
<reporter>Checkstyle</reporter>
<folder>.</folder>
<pattern>.*/target/checkstyle-result\.xml$</pattern>
</violation>
</violations>
</configuration>
</execution>
</executions>
</plugin>在极狐GitLab CI 中采集代码规范报告：
image: eclipse-temurin:8
cache:
paths:
- /root/.m2
stages:
- lint
- build
checkstyle:
allow_failure: true
stage: lint
script:
- ./mvnw checkstyle:check
artifacts:
when: always
untracked: true
report:
stage: lint
script:
- ./mvnw validate
needs:
- job: checkstyle
artifacts: true
artifacts:
reports:
codequality: gl-code-quality-report.json
compile:
stage: build
script:
- ./mvnw package -Dmaven.test.skip=true
artifacts:
untracked: true可以看到在开发人员频繁使用的「合并请求」页面，直接显示了「代码规范问题」，供开发人员自助修复以及提醒评审的同事注意，这样可以有效提高研发效率。
老项目第一次配置代码规范可能会出现很多错误（比如上图有 7746 个），没关系，先将规范合并进入主干，下次修改代码发起合并请求时，极狐GitLab 将展示「增量代码质量报告」，而无需任何复杂设置。比如下图就只有 5 个新问题了：
通过极狐GitLab CI 平滑落地 Java 增量代码规范 Checkstyle Gradle
「Java Gradle 项目」和「Java Maven 项目」的配置方法一致：
在项目中引入 Checkstyle 插件，并下载代码规范：
$ vi build.gradle
plugins {
id 'checkstyle'
}
checkstyle {
toolVersion = '9.3'
maxWarnings = 0
maxErrors = 0
}
$ mkdir -p config/checkstyle/
$ wget https://raw.githubusercontent.com/checkstyle/checkstyle/checkstyle-9.3/src/main/resources/google_checks.xml -O config/checkstyle/checkstyle.xml执行全量扫描命令，查看效果：
$ ./gradlew check
[WARN] Demo.java:6:1: 缺少 Javadoc 。 [MissingJavadocType]
[WARN] Demo.java:9:1: 行内含有制表符 tab 。 [FileTabCharacter]
[WARN] Demo.java:9:9: 'method def modifier' 缩进了8个缩进符，应为2个。 [Indentation]在极狐GitLab 持续集成中执行强制扫描：
$ vi .gitlab-ci.yml
checkstyle:
script:
- ./gradlew check同样，在项目中引入 violations-maven-plugin，它会将 Checkstyle 报告转换成极狐 GitLab 标准格式。
$ vi build.gradle
buildscript {
repositories {
maven { url 'https://plugins.gradle.org/m2/' }
}
dependencies {
classpath "se.bjurr.violations:violations-gradle-plugin:1.52.2"
}
}
task violations(type: se.bjurr.violations.gradle.plugin.ViolationsTask) {
//
// Optional config
//
maxReporterColumnWidth = 0 // 0 means "no limit"
maxRuleColumnWidth = 60
maxSeverityColumnWidth = 0
maxLineColumnWidth = 0
maxMessageColumnWidth = 50
codeClimateFile = file('gl-code-quality-report.json') // Will create a CodeClimate JSON report.
violationsFile = file('violations-file.json') // Will create a normalized JSON report.
//
// Global configuration, remove if you dont want to report violations for
// the entire repo.
//
minSeverity = 'INFO' // INFO, WARN or ERROR
detailLevel = 'VERBOSE' // PER_FILE_COMPACT, COMPACT or VERBOSE
maxViolations = 99999999 // Will fail the build if total number of found violations is higher
printViolations = true // Will print violations found in diff
//
// Diff configuration, remove if you dont want to report violations for
// files changed between specific revisions.
//
// diff-properties can be supplied with something like:
//
// ./gradlew violations -PdiffFrom=e4de20e -PdiffTo=HEAD
//
// And in Travis, you could add:
//
// script:
// - 'if [ "$TRAVIS_PULL_REQUEST" != "false" ]; then bash ./gradlew check -PdiffFrom=$TRAVIS_PULL_REQUEST_BRANCH -PdiffTo=$TRAVIS_BRANCH ; fi'
//
diffFrom = project.properties.diffFrom // Can be empty (ignored), Git-commit or any Git-reference
diffTo = project.properties.diffTo // Same as above
diffMinSeverity = 'INFO' // INFO, WARN or ERROR
diffDetailLevel = 'VERBOSE' // PER_FILE_COMPACT, COMPACT or VERBOSE
diffMaxViolations = 99 // Will fail the build if number of violations, in the diff within from/to, is higher
diffPrintViolations = true // Will print violations found in diff
gitRepo = file('.') // Where to look for Git
//
// This is mandatory regardless of if you want to report violations between
// revisions or the entire repo.
//
// Many more formats available, see: https://github.com/tomasbjerre/violations-lib
violations = [
["CHECKSTYLE", buildDir.path, ".*/checkstyle/.*\\.xml\$", "Checkstyle"]
]
}在极狐GitLab CI 中采集代码规范报告：
image: eclipse-temurin:8
cache:
paths:
- /root/.m2
stages:
- lint
- build
checkstyle:
allow_failure: true
stage: lint
script:
- ./gradlew check
artifacts:
when: always
untracked: true
report:
stage: lint
script:
- ./gradlew violations
needs:
- job: checkstyle
artifacts: true
artifacts:
reports:
codequality: gl-code-quality-report.json
compile:
stage: build
script:
- ./gradlew build -x check -x test
artifacts:
untracked: true剩余步骤与「Java Gradle 项目」一致：开发人员频繁使用的「合并请求」页面，直接显示了「代码规范问题」，供开发人员自助修复以及提醒评审的同事注意，有效提高研发效率。
老项目第一次配置代码规范可能会出现很多错误（比如上图有 7746 个），没关系，先将规范合并进入主干，下次修改代码发起合并请求时，极狐GitLab 将展示「增量代码质量报告」，而无需任何复杂设置，比如下图只有 5 个新问题：
这样，我们就通过极狐GitLab 平滑落地了 Java 增量代码规范，让项目代码越来越优雅。
java
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