了解 JPMS 模块的错误

Question

我很难理解这些错误的含义，更不用说开始解决它们了。我正在尝试将 java 平台模块（使用 jdk 14）与一个简单的“基于 gradle 的多模块”项目（使用 jdk 8 一切正常）一起使用。该项目使用 spring-boot 和 spring-data-jdbc。其实我的核心依赖是

implementation 'org.springframework.boot:spring-boot-starter-data-jdbc'
implementation 'org.springframework.boot:spring-boot-starter-freemarker'
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.projectlombok:lombok'

当我将 module-info.java 添加到每个项目源根目录时，我的 IDE (intellJ) 非常友好地提示我要导出/需要哪些模块，并且在我开始编译之前一切看起来都很好。

我在此处包含一个 git repo 链接，指向作为此问题主题的项目 - https://github.com/m41na/todo-modules-demo

如果您遇到了这些（或类似）问题，您能否说明一下您是如何解决这些问题的？

error: the unnamed module reads package org.springframework.data.jdbc.core.convert from both spring.data.jdbc and spring.data.relational
error: module spring.context reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot.starter.data.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot.starter.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.data.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot.starter reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.tx reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot.autoconfigure reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.aop reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.expression reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
the unnamed module reads package org.springframework.data.jdbc.core.convert from both spring.data.jdbc and spring.data.relational

error: module spring.core reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.boot.starter.logging reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module logback.classic reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module org.apache.logging.slf4j reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.context reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module jul.to.slf4j reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module org.slf4j reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.boot.starter.data.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module java.annotation reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.boot.starter.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module org.yaml.snakeyaml reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.jcl reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.data.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module logback.core reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
error: module spring.beans reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.boot.starter reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module spring.data.relational reads package org.springframework.data.jdbc.core.convert from both spring.data.jdbc and spring.data.relational
module spring.jdbc reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

error: module spring.data.commons reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc
module spring.tx reads package org.springframework.data.jdbc.core.convert from both spring.data.relational and spring.data.jdbc

Answer 1

TL;DR — 我已经使用 mrJar Gradle 插件解决了您的 split packages 错误 in this clone of your project¹.

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冗长的答案

„...我很难理解这些错误的含义...“

欢迎来到split packages的世界……

„...“拆分包”是一个古老的 Java 术语，其中两个具有相同名称的包存在于不同的库/应用程序中。由于配置可靠，Java 9 不允许在不同模块中拆分包……“

那句话来自this blog。

„...如果您遇到这些（或类似）问题...“

正如several other Stack Overflow questions 所证明的那样，拆分包对于将项目构建为 JPMS 模块的任何人都是不可避免的。

„...您能否说明一下您是如何解决这些问题的？...“

参考 TL;DR，我已通过应用我建议的插件解决了您项目的拆分包问题。 Download and build the demo 检查结果。

正如我在该演示文档中提到的，Java 14⁺ 支持将在接下来的一两天内添加到该插件中。一旦完成，我将更新演示并编辑此答案。但我认为，与其等到那时，你（和其他感兴趣的潜伏者）今天可以从 0.0.16 版的 JDK 13 支持中受益。

Another solution I recently proposed 是 Mark Reinhold 建议的“Bridges to the class path”方法的实现。我在 cmets 中提到的数字 2 和 3 采用了这种方法。但我个人更喜欢插件方法。这更容易，而且省力。

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^{1 我有充分的权威表明，mrJar 插件正在升级过程中，支持 JDK14+。预计将在接下来的 1-2 天内发布 v0.0.17。}