所以Java 9就在那里，很快就会出现Java 10.我们应该准备好在Java 9项目中使用我们的库。我是通过以下方式做到的：
build.gradle 到目前为止，两种方法都运行良好，我可以在Java 9项目中使用生成的Jar。
问题是，虽然我没有使用除module-info.java之外的Java 9功能，但生成的Jar与Java 8不兼容。当我设置targetCompatibility = 8时，一条错误消息告诉我也要相应地设置sourceCompatibility = 8。然后拒绝我应该设置module-info.java的{{1}}。
如何解决这个问题？
我再次移除了拼图插件，并尝试了这个，但卡住了：
sourceCompatibility = 9和sourceCompatibility = 8 targetCompatibility = 8 moduleInfo
module-info.java和sourceCompatibility = 9
现在编译工作正常，Gradle在尝试编译targetCompatibility = 9时使用Java 9。但是，缺少模块（在本例中为log4j），我收到此错误：
module-info.java这是:compileJava UP-TO-DATE
:processResources NO-SOURCE
:classes UP-TO-DATE
:jar UP-TO-DATE
:sourcesJar UP-TO-DATE
:assemble UP-TO-DATE
:spotbugsMain UP-TO-DATE
:compileModuleInfoJava
classpath:
compilerArgs: [--module-path, , --add-modules, ALL-SYSTEM]
D:\git\utility\src\module-info\java\module-info.java:14: error: module not found: org.apache.logging.log4j
requires org.apache.logging.log4j;
^
warning: using incubating module(s): jdk.incubator.httpclient
1 error
1 warning
:compileModuleInfoJava FAILED
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':compileModuleInfoJava'.
> Compilation failed; see the compiler error output for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 1s
5 actionable tasks: 1 executed, 4 up-to-date
使用的（Gradle版本是4.5.1）：
build.gradle这是plugins {
id "com.github.spotbugs" version "1.6.0"
}
apply plugin: 'maven'
apply plugin: 'maven-publish'
apply plugin: 'java-library'
apply plugin: 'com.github.spotbugs'
sourceCompatibility = 8
targetCompatibility = 8
group = 'com.dua3.utility'
repositories {
mavenLocal()
jcenter()
}
dependencies {
compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.10.0'
testRuntime group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.10.0'
// Use JUnit test framework
testImplementation 'junit:junit:4.12'
}
ext.moduleName = 'com.dua3.utility'
sourceSets {
moduleInfo {
java {
srcDir 'src/module-info/java'
}
}
}
compileModuleInfoJava {
sourceCompatibility = 9
targetCompatibility = 9
inputs.property("moduleName", moduleName)
doFirst {
options.compilerArgs = [
'--module-path', classpath.asPath,
'--add-modules', 'ALL-SYSTEM'
]
classpath = files()
System.out.println("classpath: "+classpath.asPath)
System.out.println("compilerArgs: "+options.compilerArgs)
}
}
tasks.withType(com.github.spotbugs.SpotBugsTask) {
reports {
xml.enabled false
html.enabled true
}
}
task sourcesJar(type: Jar, dependsOn: classes) {
classifier = 'sources'
from sourceSets.main.allSource
}
task javadocJar(type: Jar, dependsOn: javadoc) {
classifier = 'javadoc'
from javadoc.destinationDir
}
artifacts {
archives sourcesJar
// fails with jigsaw: archives javadocJar
}
defaultTasks 'build', 'publishToMavenLocal', 'install'
：
module-info.java答案 0 :(得分：2)
好的，我终于搞定了。如果其他人想知道如何做，这就是我所做的：
将Java版本设置为8，以便Java 8应用程序可以使用该库：
sourceCompatibility = 8
targetCompatibility = 8
配置模块名称
ext.moduleName = com.dua3.utility
添加仅包含module-info.java的新源集：
sourceSets {
moduleInfo {
java {
srcDir 'src/module-info/java'
}
}
}
为moduleInfo，sourceSet，configure modules设置与Java 9的兼容性，并设置输出目录：
compileModuleInfoJava {
sourceCompatibility = 9
targetCompatibility = 9
inputs.property("moduleName", moduleName)
doFirst {
classpath += sourceSets.main.compileClasspath
options.compilerArgs = [
'--module-path', classpath.asPath,
'--add-modules', 'ALL-SYSTEM,org.apache.logging.log4j',
'-d', sourceSets.main.output.classesDirs.asPath
]
}
}
将jar任务配置为包含moduleInfo：
jar
{
from sourceSets.main.output
from sourceSets.moduleInfo.output
}
如果您使用的是SpotBugs插件，则还必须显式配置sourceSet，否则在尝试处理ModuleInfo sourceSet时会失败。
我最终得到了这个版本的build.gradle：
plugins {
id "com.github.spotbugs" version "1.6.0"
}
apply plugin: 'maven'
apply plugin: 'maven-publish'
apply plugin: 'java-library'
apply plugin: 'com.github.spotbugs'
sourceCompatibility = 8
targetCompatibility = 8
group = 'com.dua3.utility'
repositories {
mavenLocal()
jcenter()
}
dependencies {
compile group: 'org.apache.logging.log4j', name: 'log4j-api', version: '2.10.0'
testRuntime group: 'org.apache.logging.log4j', name: 'log4j-core', version: '2.10.0'
// Use JUnit test framework
testImplementation 'junit:junit:4.12'
}
ext.moduleName = 'com.dua3.utility'
sourceSets {
moduleInfo {
java {
srcDir 'src/module-info/java'
}
}
}
compileModuleInfoJava {
sourceCompatibility = 9
targetCompatibility = 9
inputs.property("moduleName", moduleName)
doFirst {
classpath += sourceSets.main.compileClasspath
options.compilerArgs = [
'--module-path', classpath.asPath,
'--add-modules', 'ALL-SYSTEM',
'-d', sourceSets.main.output.classesDirs.asPath
]
}
}
jar
{
from sourceSets.main.output
from sourceSets.moduleInfo.output
}
spotbugs {
sourceSets = [sourceSets.main]
}
tasks.withType(com.github.spotbugs.SpotBugsTask) {
reports {
xml.enabled false
html.enabled true
}
}
task sourcesJar(type: Jar, dependsOn: classes) {
classifier = 'sources'
from sourceSets.main.allSource
}
task javadocJar(type: Jar, dependsOn: javadoc) {
classifier = 'javadoc'
from javadoc.destinationDir
}
artifacts {
archives sourcesJar
archives javadocJar
}
defaultTasks 'build', 'publishToMavenLocal', 'install'
答案 1 :(得分：0)
这个问题已有一年多的历史了，但是如果有人跌跌撞撞，那么自1.5.0版本以来， Gradle Modules Plugin 现在支持此功能。
使用此插件，您无需创建自定义源集，只需调用modularity.mixedJavaRelease方法。
以下是如何将插件应用于主build.gradle的示例：
plugins {
// your remaining plugins here
id 'org.javamodularity.moduleplugin' version '1.5.0' apply false
}
subprojects {
// your remaining subproject configuration here
apply plugin: 'org.javamodularity.moduleplugin'
modularity.mixedJavaRelease 8 // sets "--release 8" for main code, and "--release 9" for "module-info.java"
// test.moduleOptions.runOnClasspath = true // optional (if you want your tests to still run on classpath)
}