Maven dependency management (core)

Dependency configuration

 

• Dependency: Refers to the jar package required for the current project to run. A project can introduce multiple dependencies
• Configuration:
  • Write the <dependencies> tag in pom.xml
  • Use <dependency> in the <dependencies> tag to introduce coordinates
  • Define the groupId, artifactacId, version of the coordinates
  • Click the refresh button to import the newly added coordinates

ps: If the imported dependency does not exist in the local warehouse, it will connect to the remote warehouse/central warehouse, and then download the dependencies; if you do not know the coordinate information of the dependencies, you can go to Maven Repository: Search/Browse/Explore (mvnrepository.com) to query

dependency transitive

• Dependency is transitive
• Direct dependency: the dependency relationship established through dependency configuration in the current project
• Indirect dependency: If the dependent resource depends on other resources, the current project indirectly depends on other resources
  • 
  • There will also be FirstTest in the WebTest project: 1.0/2.0Jar package

Specific examples are as follows:

First prepare multiple interdependent maven projects

First look at the pom.xml file of the A project

 Where A project depends on B project

The pom.xml file in the same B project shows

 Project B depends on project C

Finally look at the C project

 From the above, it can be known that project A does not directly depend on project C, but indirectly depends on project C through project B.

The specific diagram is as follows:

 ps: In the professional version of the two point idea, you can view the dependencies of the maven project through the view

details as follows:

Right-click the icon in the maven project that needs to be viewed--Show dependencies

 The final result is as follows:

 to clearly show dependencies

• Exclude dependencies: When actively disconnecting dependent resources, the excluded resources do not need to specify a version

Exclude dependencies by using the <exclusions></exclusions> tag in the pom.xml file

Taking the above project A as an example, the operation is as follows:

looking at dependencies

 Completed dependency exclusion

Dependency scope

• The dependent jar package, by default, can be used anywhere. The scope of use can be set through the <scope>...</scope> tag , the scope of action:
  • The scope of the main program is valid. (within the scope of the main folder)
  • The test program scope is valid. (in the scope of the test folder)
  • Whether to participate in packaging and running. (package directive scope)
• Common values ​​of scope
  • 

Maven life cycle

Mavnen's life cycle is to abstract and unify all maven project build processes

There are 3 sets of independent life cycles in Maven

• clean: cleaning work
• default: core work: compilation, testing, packaging, installation, deployment, etc.
• site: Generate reports, publish sites

1. clean life cycle: This life cycle is used to clean up the project, including deleting generated files and directories. It includes the following stages:

   • pre-clean: perform pre-cleaning preparations.
   • clean: Clean generated files and directories.
   • post-clean: the operation after cleaning.

2. default life cycle: This life cycle is the core life cycle of building projects, used for compilation, testing, packaging, deployment, etc. It includes the following stages:

   • validate: Validates that the item is correct and all necessary information is available.
   • compile: Compile the source code of the project.
   • test: Test the compiled source code with an appropriate unit testing framework.
   • package: Package compiled code into a distributable format, such as JAR.
   • verify: Check the results of integration tests.
   • install: Install the package to the local warehouse for use by other local projects.
   • deploy: Copy the final package to a remote repository for use by other developers and projects.

3. site life cycle: This life cycle is used to generate the project's site documentation. It includes the following stages:

   • pre-site: perform preparatory work before generating site documents.
   • site: Generates the project's site documentation.
   • post-site: operations after generating site documents, such as deploying the site to the server.
   • site-deploy: Deploy the generated site documentation to the server.

 ps: In the same set of life cycle , when the later stage is run, the previous stage will be run

execution life cycle

•  In the idea, on the maven toolbar on the right, select the corresponding life cycle, double-click to execute

   

  • 
• On the command line, execute the command
  • mvn + stage name to execute
    • mvn clean

ps: The operation of each life cycle is completed through the corresponding plug-in, the essence of mavne is a plug-in execution framework