POM in Maven Detailed introduction to XML configuration file
setting. XML is mainly used to configure a series of general attributes such as Maven's running environment. It is a global level configuration file; POM XML mainly describes the Maven coordinates of the project, dependencies, rules that developers need to follow, defect management system, organization and licenses, and all other project related factors. It is a project level configuration file.
Basic configuration
A typical POM The XML file configuration is as follows:
Generally speaking, the above configuration items are essential to any project and define the basic properties of the project.
Here, it is necessary to explain a less commonly used attribute classifier, because sometimes if a jar package is referenced, the classifier will report an error if it is not written.
The classifier element is used to help define some subsidiary components of the component output. The auxiliary component corresponds to the main component. For example, the main component is kimi-app-2.0 0. Jar, which may also be generated by using some plug-ins, such as kimi-app-2.0 0-javadoc. Jar (Java document) and kimi-app-2.0.0-sources.jar (Java source code). At this time, Javadoc and sources are the classifiers of these two auxiliary components, so that the auxiliary components have their own unique coordinates.
The purpose of classifier is to:
1. When Maven downloads Javadoc / sources jar package, you need to use the classifier to indicate which accessory component to download
2. When introducing dependencies, sometimes a component cannot be uniquely determined only by groupid, artifactid and version, and the classifier needs to be used to further clarify the goal. For example, JSON lib sometimes provides multiple jar packages together with one version, which is in jdk1 5 environment is a set, in jdk1 3 environment is a set of:
When quoting it, you should indicate the JDK version, otherwise Maven doesn't know which jar package you need:
Build configuration
The warehouse and setting in POM The warehouse function in XML is the same. The main difference is that the warehouse in POM is personalized. For example, the setting file in a large company is public, and all projects use one setting file, but each sub project will refer to different third-party libraries, so you need to set the warehouse address you need in POM.
Distribution configuration
Warehouse configuration
Profile configuration
The profile configuration item is in setting XML, POM A cropped version of the profile element in XML, including ID, activation, repositories, pluginrepositories, and properties elements. The profile element here only contains these five child elements because setting XML only cares about building the system as a whole (which is the role orientation of the settings.xml file), rather than individual project object model settings. If a profile in settings is activated, its value will overwrite any other profile with the same ID defined in POM or profile.xml.
pom. The profile in XML can be regarded as POM XML, with POM XML has the same child elements and configuration methods. It contains optional activation (trigger of profile) and a series of changes. For example, the test process may point to different databases (relative to the final deployment) or different dependencies or different repositories, which are changed according to different jdks. Only one of them is valid to activate the profile. If the first condition is met, there will be no matching later.
Report configuration
Environment configuration
Project information configuration
summary
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