java - Maven 不会部署依赖项

Question

我有一个具有 3 个依赖项的简单项目，但出于某种原因，当我从 eclipse run as -> maven install 运行时。我没有得到依赖项。不在快照 jar 内，也不在外面......任何的想法？这是我的 pom:

<?xml version="1.0"?>
<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>com</groupId>
  <artifactId>trade</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>
  <name>trade</name>
  <url>http://maven.apache.org</url>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.6</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>log4j</groupId>
      <artifactId>log4j</artifactId>
      <version>1.2.12</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>
</project>

Answer 1

(...) I don't get the dependencies. not inside the snapshot jar and not outside... any idea?

是的:对于具有 jar 的项目来说，这是不应该发生的包装。创建的 jar“仅”包含项目中的类，依赖项“仅”在编译和测试执行期间使用。

摘自依赖机制简介:

Dependency Scope

Dependency scope is used to limit the transitivity of a depedency, and also to affect the classpath used for various build tasks.

There are 6 scopes available:

• compile
  This is the default scope, used if none is specified. Compile dependencies are available in all classpaths of a project. Furthermore, those dependencies are propagated to dependent projects.
• provided
  This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.
• runtime
  This scope indicates that the dependency is not required for compilation, but is for execution. It is in the runtime and test classpaths, but not the compile classpath.
• test
  This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases.
• system
  This scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository.
• import (only available in Maven 2.0.9 or later)
  This scope is only used on a dependency of type pom in the <dependencyManagement> section. It indicates that the specified POM should be replaced with the dependencies in that POM's <dependencyManagement> section. Since they are replaced, dependencies with a scope of import do not actually participate in limiting the transitivity of a dependency.

...

如果您想构建一个包含依赖项的独立可执行 jar，请考虑使用 Maven Assembly Plugin和预定义的 jar-with-dependencies描述符。看看这些以前的答案:

• Building a runnable jar with maven 2
• Is it possible to create an “uber” jar containing the project classes and the project dependencies as jars with a custom manifest file?
• Problem building executable jar with maven

其他选项包括 maven shade plugin , onejar-maven-plugin .对于简单的用例，我建议使用 assembly 插件。