如何将非模块化Maven依赖项作为自动模块添加到模块路径？

问题描述

让我们说我们想构建一个具有单个非模块化依赖项org.json:json的简单Java 11模块化Maven项目（出于实际示例的目的随机选取）。

项目结构：

project
|-- pom.xml
`-- src
    `-- main
        `-- java
            |-- foo.bar.project
            |   `-- foo
            |       `-- bar
            |           `-- project
            |               `-- Foo.java
            `-- module-info.java

Foo.java ：

package foo.bar.project;

import org.json.JSONObject;

public class Foo {
    static JSONObject o = new JSONObject();
}

module-info.java ：

module foo.bar.project {
}

pom.xml ：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>foo.bar</groupId>
  <artifactId>project</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.release>11</maven.compiler.release>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.json</groupId>
      <artifactId>json</artifactId>
      <version>20200518</version>
    </dependency>
  </dependencies>

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.8.1</version>
          <executions>
            <execution>
                <goals>
                    <goal>compile</goal>
                </goals>
                <id>compile</id>
            </execution>
          </executions>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

---

我的问题是如何告诉Maven将org.json作为自动模块放在模块路径上。默认情况下，Maven将非模块化jar作为未命名模块放置在classpath上。

按现状，运行mvn clean compile失败，并显示以下信息：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.1:compile (default-compile) on project project: Compilation failure
[ERROR] <PathToProject>/src/main/java/foo.bar.project/foo/bar/project/Foo.java:[3,11] package org.json is not visible
[ERROR]   (package org.json is declared in the unnamed module,but module org.json does not read it)
[ERROR]
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors,re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions,please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException

---

系统信息：

Apache Maven 3.6.0 (97c98ec64a1fdfee7767ce5ffb20918da4f719f3; 2018-10-24T20:41:47+02:00)
Maven home: C:\Tools\apache-maven-3.6.0
Java version: 11.0.1,vendor: Oracle Corporation,runtime: C:\Program Files\Java\jdk-11.0.1
Default locale: sl_SI,platform encoding: UTF8
OS name: "windows 10",version: "10.0",arch: "amd64",family: "windows"

解决方法

我找到了消息

[错误]（包org.json在未命名的模块中声明，但是 org.json模块无法读取）

奇怪，它应该已经读过“。但是模块def wrapper():却没有读过它”

然后，您将发现需要在foo.bar.project中放置一条指令，例如：

module-info.java