问题
I’m using Maven 3.3.3 with Java 8 on Mac Yosemite. I have a multi-module project.
<modules>
<module>first-module</module>
<module>my-module</module>
…
</modules>
When I build my one of my child modules, for example, “my-module” from above, using “mvn clean install”, the build attempts to download the child module artifacts from a remote repository I have defined in my ~/.m2/settings.xml file. Output is below
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building my-module 87.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml
Downloading: http://download.java.net/maven/2/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml
Downloaded: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml (788 B at 0.9 KB/sec)
Downloading: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/first-module-87.0.0-20151104.200545-4.pom
How do I force Maven to check my local ~/.m2/repository first before trying to download from the remote repositories? Below is where I have my remote repositories defined in my ~/.m2/settings.xml file …
<profile>
<id>releases</id>
<activation>
<property>
<name>!releases.off</name>
</property>
</activation>
<repositories>
<repository>
<id>releases</id>
<url>https://my.remoterepository.com/nexus/content/repositories/releases/</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
</profile>
<profile>
<id>snapshots</id>
<activation>
<property>
<name>!snapshots.off</name>
</property>
</activation>
<repositories>
<repository>
<id>snapshots</id>
<url>https://my.remoterepository.com/nexus/content/repositories/snapshots/</url>
<releases>
<enabled>false</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</repository>
</repositories>
</profile>
Edit: In response to the answer saying that the download occurs when the artifact is not there, below is the terminal output in which I prove the file was there in my repo but Maven is trying to download it anyway ...
Daves-MacBook-Pro-2:my-module davea$ ls -al ~/.m2/repository/org/mainco/subco/first-module/87.0.0-SNAPSHOT/first-module-87.0.0-SNAPSHOT.jar
-rw-r--r-- 1 davea staff 10171 Nov 5 10:22 /Users/davea/.m2/repository/org/mainco/subco/first-module/87.0.0-SNAPSHOT/first-module-87.0.0-SNAPSHOT.jar
Daves-MacBook-Pro-2:my-module davea$ mvn clean install
[INFO] Scanning for projects...
[WARNING]
[WARNING] Some problems were encountered while building the effective model for org.mainco.subco:my-module:jar:87.0.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-antrun-plugin @ org.mainco.subco:my-module:[unknown-version], /Users/davea/Documents/sb_workspace/my-module/pom.xml, line 678, column 12
[WARNING]
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING]
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING]
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building my-module 87.0.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
Downloading: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml
Downloading: http://download.java.net/maven/2/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml
Downloaded: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/maven-metadata.xml (788 B at 0.8 KB/sec)
Downloading: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/first-module-87.0.0-20151106.043202-8.pom
Downloaded: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/first-module/87.0.0-SNAPSHOT/first- module-87.0.0-20151106.043202-8.pom (3 KB at 21.9 KB/sec)
Downloading: http://download.java.net/maven/2/org/mainco/subco/subco/87.0.0-SNAPSHOT/maven-metadata.xml
Downloading: https://my.remoterepository.com/nexus/content/repositories/snapshots/org/mainco/subco/subco/87.0.0-SNAPSHOT/maven-metadata.xml
回答1:
The dependency has a snapshot version. For snapshots, Maven will check the local repository and if the artifact found in the local repository is too old, it will attempt to find an updated one in the remote repositories. That is probably what you are seeing.
Note that this behavior is controlled by the updatePolicy directive in the repository configuration (which is daily by default for snapshot repositories).
回答2:
Use mvn --help and you can see the options list.
There is an option like -nsu,--no-snapshot-updates Suppress SNAPSHOT updates
So use command mvn install -nsu can force compile with local repository.
回答3:
To truly force maven to only use your local repo, you can run with mvn <goals> -o. The -o tells maven to let you work "offline", and it will stay off the network.
回答4:
In my case I had a multi module project just like you. I had to change a group Id of one of the external libraries my project was depending on as shown below.
From:
<dependencyManagement>
<dependency>
<groupId>org.thirdparty</groupId>
<artifactId>calculation-api</artifactId>
<version>2.0</version>
<type>jar</type>
<scope>provided</scope>
</dependency>
<dependencyManagement>
To:
<dependencyManagement>
<dependency>
<groupId>org.thirdparty.module</groupId>
<artifactId>calculation-api</artifactId>
<version>2.0</version>
<type>jar</type>
<scope>provided</scope>
</dependency>
<dependencyManagement>
Pay attention to the <groupId> section. It turned out that I was forgetting to modifiy the corresponding section of the submodules that define this dependency in their pom files.
It drove me very crazy because the module was available locally.
回答5:
The -o option didn't work for me because the artifact is still in development and not yet uploaded and maven (3.5.x) still tries to download it from the remote repository because it's the first time, according to the error I get.
However this fixed it for me: https://maven.apache.org/general.html#importing-jars
After this manual install there's no need to use the offline option either.
UPDATE
I've just rebuilt the dependency and I had to re-import it: the regular mvn clean install was not sufficient for me
回答6:
Follow below steps:
1.Ensure to delete all the contents of the jar folder located in your local except the jar that you want to keep.
For example files like .repositories, .pom, .sha1, .lastUpdated etc.
2.Execute mvn clean install -o command
This will help to use local repository jar files rather than connecting to any repository.
回答7:
Maven always checks your local repository first, however,your dependency needs to be installed in your repo for maven to find it.
Run mvn install in your dependency module first, and then build your dependent module.
来源：https://stackoverflow.com/questions/33548395/how-do-i-force-maven-to-use-my-local-repository-rather-than-going-out-to-remote