JDK9中预定义的模块是什么?或者我需要修复依赖关系的模块? [英] What are the predefined modules in JDK9 or Which module do I need to fix dependency problems?

问题描述

JDK9将(可能)引入一个模块系统.作为其一部分，Java类库将被模块化.

JDK9 will (probably) introduce a module system. As part of that, the Java Class Library will get modularized.

当找不到类时可能会导致异常，因为它们位于尚未指定为依赖项的模块中.

This can lead to exceptions when classes don't get found because they are in a module that isn't specified as a dependency yet.

将由模块系统创建的模块是什么，它们各自的内容是什么?

What are the modules that will get created with the module system and what is their respective content?

或者换句话说:给定一个未加载的类，我如何找到合适的模块作为依赖项包含?

Or stated differently: Given a class that doesn't get loaded, how do I find the proper module to include as a dependency?

推荐答案

我如何找到合适的模块作为依赖项?

how do I find the proper module to include as a dependency?

考虑这个欺骗类:

import java.sql.DriverManager;
import java.rmi.RemoteException;

public class UserDao {
    DriverManager driverManager = null;

    public void service() throws RemoteException {
        if (true) {
            throw new RemoteException();
        }
    }
}

让我们假设此类已编译为user-dao.jar.答案是jdeps工具(使用9ea170):

Let's assume that this class is compiled into user-dao.jar. The jdeps tool is the answer (using 9ea170):

jdeps --list-deps user-dao.jar
   java.base
   java.rmi
   java.sql

(请注意，jdeps随JDK 8一起提供，但在JDK 9中更合适.)

(Note that jdeps shipped with JDK 8 but is much more appropriate in JDK 9.)

出于完整性考虑，如果您知道代码使用特定的类(例如java.sql.DriverManager)并且怀疑需要一个模块(例如java.sql)，则可以通过

For completeness, if you know that the code uses a specific class (e.g. java.sql.DriverManager) and you suspect a module is required (e.g. java.sql), one could confirm the module via the doc, or on the command-line (again with 9ea170):

bash$ java --describe-module java.sql
java.sql@9-ea
exports java.sql
exports javax.sql
exports javax.transaction.xa
requires java.xml transitive
requires java.base mandated
requires java.logging transitive
uses java.sql.Driver

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