preface

Yesterday, a reader asked me about my work experience and accidentally raised an interesting question as follows:

The company is developing multiple modules recently. Because of the interdependence between modules, it is very troublesome to package each module. We must package each module according to the dependency relationship.

As anyone who plays Maven knows, all it takes is one command to solve the problem.

dependencies

Suppose there is A multi-module project, the parent project P contains three sub-modules A, B and C, and the three modules have the following dependencies:

  1. A depends on B and C.
  2. B depends on C.

Dependency diagram

The pom.xml of the parent project P is as follows:

. <modules> <module>A</module> <module>B</module> <module>C</module> </modules> .....Copy the code

The pom.xml of module A is as follows:

. <dependency> <groupId>xxx.xxxx</groupId> <artifactId>B</artifactId> <version>xxxx</version> </dependency> .....Copy the code

The pom.xml of module B is as follows:

. <dependency> <groupId>xxx.xxxx</groupId> <artifactId>C</artifactId> <version>xxxx</version> </dependency> .....Copy the code

The pom.xml of module C is as follows:

.Copy the code

What would you do?

Now the product needs to go online project A, how should you package it?

The most obvious is to pack them separately and execute the following commands:

mvn clean install C
mvn clean install B
mvn clean package A
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The above three modules take turns to pack, at least it takes more than five minutes, don’t you panic?

A batch of panic

Here’s the thing: ALL I need is the following command:

mvn clean package -pl A -am -P test -DskipTests=true
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What’s the meaning of this order? ** -p specifies the environment, -dskiptests =true skips the tests, but what are -pl and -**am?

**-pl and -**am

A few parameters you need to know

**-pl and -**am are both important parameters. As follows:

The value is artifactId-am. It is optional to process the dependent modules of the module specified by the PL parameter. – AMD Is optional to process the dependent modules of the module specified by the PL parameter

How’s it going? Does that make sense? Is it a little obscure, ha ha….

what?

Don’t worry, here are a few commands to understand (all in the parent project P root directory).

  1. mvn clean install -pl A -am

Perform MVN clean Install on parent project P, child module A, and modules B and C on which module A depends.

After the command is successfully executed, modules P, A, B, and C are installed locally.

  1. mvn clean install -pl C -am

Perform MVN clean install on parent project P and child module C.

After the command is executed successfully, you can see that modules P and C are installed locally.

Module C is “independent” of the other two sub-modules, so modules A and B do not run related commands.

  1. mvn clean install -pl C -amd

Perform MVN clean install on parent project P, child module C, and modules B** and **C that depend on module C.

After the command is successfully executed, modules P, A, B, and C are installed locally.

  1. mvn clean install -N

Only the parent project P will be packaged, and its child modules will not perform relevant operations.

How’s that？ Through the above command should understand it.

conclusion

As the volume of the project gradually grows, there are more than a few modules above, and the efficiency can be more than doubled by learning the above commands.

The last

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