Maven介绍

Maven依赖关系、作用域以及编译打包

依赖配置

Dependency Optional

示例：

<project>
  ...
  <dependencies>
    <!-- declare the dependency to be set as optional -->
    <dependency>
      <groupId>sample.ProjectA</groupId>
      <artifactId>Project-A</artifactId>
      <version>1.0</version>
      <scope>compile</scope>
      <optional>true</optional> <!-- value will be true or false only -->
    </dependency>
  </dependencies>
</project>

How do optional dependencies work?

1	Project-A -> Project-B

The diagram above says that Project-A depends on Project-B. When A declares B as an optional dependency in its POM, this relationship remains unchanged. It’s just like a normal build where Project-B will be added in Project-A’s classpath.

1	Project-X -> Project-A

When another project (Project-X) declares Project-A as a dependency in its POM, the optional nature of the dependency takes effect. Project-B is not included in the classpath of Project-X. You need to declare it directly in the POM of Project X for B to be included in X’s classpath.

Dependency Scope

Dependency scope is used to limit the transitivity of a dependency, 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. This scope is not transitive.
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
This scope is only supported on a dependency of type pom in the <dependencyManagement> section. It indicates the dependency to be replaced with the effective list of dependencies in the specified 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.

编译配置

显示错误日志信息

编译、打包时报错分析, 添加编译参数：

1	mvn clean package -D maven.test.skip=true -e -X

Maven指定模块

1	mvn -pl ainsurtech-agent -am clean package -P uat -U -D maven.test.skip=true