Maven: best way of linking custom external JAR to

问题:

It's my first couple of days learning Maven and I'm still struggling with the basics. I have an external .jar file (not available in the public repos) that I need to reference in my project and I'm trying to figure out what my best option is.

It's a small scale project without a central repository for libraries, so it has to be either a local repository (somehow added to source control, don't know if it's supposed to work that way?) or the .jar needs to be stored on disk outside of any formal repository.

1) What's my best option for adding the .jar file to my project's references with maven given that I want both the project and the library to be in source control?

2) I still can't seem to have Eclipse see the dependency. I manually added it to the section of the pom, and it shows up fine in the Dependencies list in m2eclipse. mvn compile and mvn package both succeed, but running the program results in:

Exception in thread "main" java.lang.Error: Unresolved compilation problems:
        LibraryStuff cannot be resolved to a type

This is after editing the POM as:

<dependency>
  <groupId>stuff</groupId>
  <artifactId>library</artifactId>
  <version>1.0</version>
  <systemPath>${lib.location}/MyLibrary.jar</systemPath>
  <scope>system</scope>
</dependency>

Should I be executing mvn install:install-file even thought I already have the pom.xml edited as above?

Thanks!

回答1:

I think you should use mvn install:install-file to populate your local repository with the library jars then you should change the scope from system to compile.

If you are starting with maven I suggest to use maven directly not IDE plugins as it adds an extra layer of complexity.

As for the error, do you put the required jars on your classpath? If you are using types from the library, you need to have access to it in the runtime as well. This has nothing to do with maven itself.

I don't understand why you want to put the library to source control - it is for sources code not binary jars.

回答2:

You can create an In Project Repository, so you don't have to run mvn install:install-file every time you work on a new computer

<repository>
    <id>in-project</id>
    <name>In Project Repo</name>
    <url>file://${project.basedir}/libs</url>
</repository>

<dependency>
    <groupId>dropbox</groupId>
    <artifactId>dropbox-sdk</artifactId>
    <version>1.3.1</version>
</dependency>

/groupId/artifactId/version/artifactId-verion.jar

detail read this blog post

http://charlie.cu.cc/2012/06/how-add-external-libraries-maven/

回答3:

The Maven manual says to do this:

mvn install:install-file -Dfile=non-maven-proj.jar -DgroupId=some.group -DartifactId=non-maven-proj -Dversion=1 -Dpackaging=jar

回答4:

This can be easily achieved by using the <scope> element nested inside <dependency> element.

For example:

 <dependencies>
   <dependency>
     <groupId>ldapjdk</groupId>
     <artifactId>ldapjdk</artifactId>
     <scope>system</scope>
     <version>1.0</version>
     <systemPath>${basedir}\src\lib\ldapjdk.jar</systemPath>
   </dependency>
 </dependencies>

Reference: http://www.tutorialspoint.com/maven/maven_external_dependencies.htm

回答5:

update We have since just installed our own Nexus server, much easier and cleaner.

At our company we had some jars that we some jars that were common but were not hosted in any maven repositories, nor did we want to have them in local storage. We created a very simple mvn (public) repo on Github (but you can host it on any server or locally):
note that this is only ideal for managing a few rarely chaning jar files

1. Create repo on GitHub:
   https://github.com/<user_name>/mvn-repo/

2. Add Repository in pom.xml
   (Make note that the full path raw file will be a bit different than the repo name)
   

   <repository>
       <id>project-common</id>
       <name>Project Common</name>
       <url>https://github.com/<user_name>/mvn-repo/raw/master/</url>
   </repository>
   

3. Add dependency to host (Github or private server)
   a. All you need to know is that files are stored in the pattern mentioned by @glitch
   /groupId/artifactId/version/artifactId-version.jar
   b. On your host create the folders to match this pattern.
   i.e if you have a jar file named service-sdk-0.0.1.jar, create the folder service-sdk/service-sdk/0.0.1/ and place the jar file service-sdk-0.0.1.jar into it.
   c. Test it by trying to download the jar from a browser (in our case: https://github.com/<user_name>/mvn-repo/raw/master/service-sdk/service-sdk/0.0.1/service-sdk-0.0.1.jar
   

4. Add dependency to your pom.xml file:
   

   <dependency>
       <groupId>service-sdk</groupId>
       <artifactId>service-sdk</artifactId>
       <version>0.0.1</version>
   </dependency>
   

5. Enjoy

回答6:

Don't use systemPath. Contrary to what people have said here, you can put an external jar in a folder under your checked-out project directory and haven Maven find it like other dependencies. Here are two crucial steps:

1. Use "mvn install:install-file" with -DlocalRepositoryPath.
2. Configure a repository to point to that path in your POM.

It is fairly straightforward and you can find a step-by-step example here: http://randomizedsort.blogspot.com/2011/10/configuring-maven-to-use-local-library.html

回答7:

Maven way to add non maven jars to maven project

Maven Project and non maven jars

Add the maven install plugins in your build section

<plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-install-plugin</artifactId>
        <version>${version.maven-install-plugin}</version>
        <executions>

            <execution>
                <id>install-external-non-maven1-jar</id>
                <phase>clean</phase>
                <configuration>
                    <repositoryLayout>default</repositoryLayout>
                    <groupId>jar1.group</groupId>
                    <artifactId>non-maven1</artifactId>
                    <version>${version.non-maven1}</version>
                    <file>${project.basedir}/libs/non-maven1.jar</file>
                    <packaging>jar</packaging>
                    <generatePom>true</generatePom>
                </configuration>
                <goals>
                    <goal>install-file</goal>
                </goals>
            </execution>
            <execution>
                <id>install-external-non-maven2-jar</id>
                <phase>clean</phase>
                <configuration>
                    <repositoryLayout>default</repositoryLayout>
                    <groupId>jar2.group</groupId>
                    <artifactId>non-maven2</artifactId>
                    <version>${version.non-maven2}</version>
                    <file>${project.basedir}/libs/non-maven2.jar</file>
                    <packaging>jar</packaging>
                    <generatePom>true</generatePom>
                </configuration>
                <goals>
                    <goal>install-file</goal>
                </goals>
            </execution>
            <execution>
                <id>install-external-non-maven3-jar</id>
                <phase>clean</phase>
                <configuration>
                    <repositoryLayout>default</repositoryLayout>
                    <groupId>jar3.group</groupId>
                    <artifactId>non-maven3</artifactId>
                    <version>${version.non-maven3}</version>
                    <file>${project.basedir}/libs/non-maven3.jar</file>
                    <packaging>jar</packaging>
                    <generatePom>true</generatePom>
                </configuration>
                <goals>
                    <goal>install-file</goal>
                </goals>
            </execution>
        </executions>
    </plugin>

Add the dependency

<dependencies>
    <dependency>
        <groupId>jar1.group</groupId>
        <artifactId>non-maven1</artifactId>
        <version>${version.non-maven1}</version>
    </dependency>
    <dependency>
        <groupId>jar2.group</groupId>
        <artifactId>non-maven2</artifactId>
        <version>${version.non-maven2}</version>
    </dependency>
    <dependency>
        <groupId>jar3.group</groupId>
        <artifactId>non-maven3</artifactId>
        <version>${version.non-maven3}</version>
    </dependency>
</dependencies>

References Note I am the owner of the blog

回答8:

Change your systemPath.

<dependency>
  <groupId>stuff</groupId>
  <artifactId>library</artifactId>
  <version>1.0</version>
  <systemPath>${project.basedir}/MyLibrary.jar</systemPath>
  <scope>system</scope>
</dependency>

回答9:

If you meet the same problem and you are using spring-boot v1.4+, you can do it in this way.

There is an includeSystemScope that you can use to add system-scope dependencies to the jar.

e.g.

I'm using oracle driver into my project.

<dependency>
        <groupId>com.oracle</groupId>
        <artifactId>ojdbc14</artifactId>
        <version>10.2.0.3.0</version>
        <scope>system</scope>
        <systemPath>${project.basedir}/src/main/resources/extra-jars/ojdbc14-10.2.0.3.0.jar</systemPath>
    </dependency>

then make includeSystemScope=true to include the jar into path /BOOT-INF/lib/**

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <configuration>
        <includeSystemScope>true</includeSystemScope>
    </configuration>
</plugin>

and exclude from resource to avoid duplicated include, the jar is fat enought~

<build>
    <testSourceDirectory>src/test/java</testSourceDirectory>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <excludes>
                <exclude>**/*.jar</exclude>
            </excludes>
        </resource>
    </resources>
</build>

Good luck!

回答10:

The pom.xml is going to look at your local repository to try and find the dependency that matches your artifact. Also you shouldn't really be using the system scope or systemPath attributes, these are normally reserved for things that are in the JDK and not the JRE

See this question for how to install maven artifacts.

回答11:

The best solution here is to install a repository: Nexus or Artifactory. If gives you a place to put things like this, and further it speeds things up by caching your stuff from the outside.

If the thing you are dealing with is open source, you might also consider putting in into central.

See the guide.

回答12:

Note that all of the example that use

<repository>...</respository> 

require outer

<repositories>...</repositories> 

enclosing tags. It's not clear from some of the examples.

回答13:

If the external jar is created by a Maven project only then you can copy the entire project on your system and run a

mvn install

in the project directory. This will add the jar into .m2 directory which is local maven repository.

Now you can add the

<dependency>
     <groupId>copy-from-the=maven-pom-of-existing-project</groupId>
     <artifactId>copy-from-the=maven-pom-of-existing-project</artifactId>
     <version>copy-from-the=maven-pom-of-existing-project</version>
</dependency>

This will ensure that you

mvn exec:java 

works. If you use suggested here

<scope>system</scope>

Then you will have to add classes individually while using executing through command line.

You can add the external jars by the following command described here

mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> \
-DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>

回答14:

With Eclipse Oxygen you can do the below things:

1. Place your libraries in WEB-INF/lib
2. Project -> Configure Build Path -> Add Library -> Web App Library

Maven will take them when installing the project.