Guide on how to correctly import Jar packages into Maven projects

Maven Getting Started Guide: How to correctly import a Jar package?

Maven is a powerful project management tool that can help developers manage project dependencies, build projects, etc. During project development, we often need to import external Jar packages to implement some functions. This article will introduce how to use Maven to correctly import Jar packages and provide specific code examples.

First, we need to add dependency on the required Jar package in Maven's pom.xml file. In pom.xml, there is a <dependencies></dependencies> tag used to manage project dependencies. We can add the dependency information of the required Jar package in this tag. Specific dependency information includes the coordinates and version of the Jar package, etc.

The following is an example pom.xml file, which contains the dependencies for importing the commons-lang Jar package:

<project>
    <!-- 其他配置信息 -->
    
    <dependencies>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.9</version>
        </dependency>
    </dependencies>
</project>

In this example, The <groupid></groupid> tag indicates the organization name of the Jar package, the <artifactid></artifactid> tag indicates the name of the Jar package, and the <version></version> tag indicates the version number of the Jar package. This information can generally be found in the Maven repository.

Once the dependencies of the Jar packages are added to the pom.xml file, Maven will automatically download and import these Jar packages into the project. If you are using an integrated development environment (IDE) such as Eclipse, IntelliJ IDEA, etc., the IDE will automatically load these Jar packages and you can use them directly in the project.

In addition to automatically downloading external Jar packages, Maven can also help us package the project into an executable Jar package. In the pom.xml file, this function can be achieved by configuring the plug-in. The following is an example plug-in configuration:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <version>3.1.1</version>
            <configuration>
                <archive>
                    <manifest>
                        <mainClass>com.example.Main</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

In this plug-in configuration, the <mainclass></mainclass> tag specifies the main class of the project. When we execute mvn package When executing the command, Maven will automatically package the project into an executable Jar package. The Jar package can be executed through the command line to run the project.

To summarize, it is very convenient to use Maven to manage project dependencies and import Jar packages correctly. By simply configuring the pom.xml file, we can automatically download and import Jar packages, thereby speeding up project development. I hope this article can help you better understand how to correctly import Jar packages.

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