I am attempting to send a simple HTTP post from a java program (for deploying on Heroku).
I started with the demo project here.
Using mvn package builds the project successfully.
I then added my own additional file TestPost.java with a few lines of code, added it to the pom.xml, and still built fine.
Then I tried to add the HTTP code from this example (minus the package line), which uses the Apache HttpClient library.
Using mvn package results in the following error:
package org.apache.http does not exist
After searching for solutions I tried including a dependency in the pom.xml:
<dependencies>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
<scope>compile</scope>
</dependency>
</dependencies>
My understanding was that this should force a download of the necessary package but no download was shown on the next compile (just the same error), and the package is not visible in my user .m2\repository\ folder.
I tried inserting this dependency at different points in my pom.xml without success.
Why is the apache library not being downloaded? Please note that I am new to maven.
Here is the pom.xml that you should have if indeed you need to depend on httpclient.
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>demo</groupId>
<artifactId>httpclient-demo</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>httpclient-demo</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.5.2</version>
</dependency>
</dependencies>
</project>
Now if you put your Java sources in src/main/java, where src and pom.xml are in the same directory, Maven should resolve the dependency from your local repository, and download it, should it not already be there. Your local repository is defined in the conf/settings.xml in your Maven installation directory.
Related
I'm trying to use Google cloud storage and I'm following this guide: https://cloud.google.com/storage/docs/reference/libraries#using_the_client_library
I'm using Java with Maven, and this is my Pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.findwise.app</groupId>
<artifactId>data-pipeline</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-pubsub</artifactId>
<version>0.32.0-beta</version>
</dependency>
<dependency>
<groupId>com.google.cloud.dataflow</groupId>
<artifactId>google-cloud-dataflow-java-sdk-all</artifactId>
<version>2.2.0</version>
</dependency>
<dependency>
<groupId>com.google.cloud</groupId>
<artifactId>google-cloud-storage</artifactId>
<version>1.70.0</version>
</dependency>
</dependencies>
</project>
As you can see I've added the google-cloud-storage dependency. My problem is that the classes used in the Java part of the guide (Storage, StorageOptions, Bucket, BucketInfo) are unfindable by IntelliJ. I can't import them. In fact, when I try to import via the absolute path:
import com.google.cloud.storage.Storage;
IntelliJ complains that the symbol google cannot be resolved. What is wrong here?
There are a few places to look:
Find your local .m2 repository and navigate to the com.google.cloud dependencies. If you don't find it, or the JARs aren't there, IntelliJ won't be able to access them.
IntelliJ will show you the External Libraries it is using under your source code in the project panel on the left.
If IntelliJ cannot import the class, it suggests that your Maven pull isn't working.
I've looked here https://blog.packagecloud.io/eng/2017/03/09/how-does-a-maven-repository-work/ and that does seem to be the case.
However, I tried to experiment with mvn install and I'm not sure if it's worked as expected. Here's what I did
(1) I created a lib.
(2) Ran mvn install from the command line
(3) Copied the path of my newly created jar
(4) Opened a new maven project, stuck the path into my pom.xml
I'm able to reuse my library methods, BUT: one of my library methods returns a TransportClient which is part of the elasticsearch api. Using intellij inside my new project, it seems like I don't have elasticsearch even though I'm referencing the jar.
Is this expected? I was expecting it to have transitively installed elasticsearch when it referenced my jar.
I'd love a pointer or two in the right direction, I'm completely new to this. :)
My pom.xml for the lib that uses elasticsearch as dependency.
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<properties>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
</properties>
<groupId>estutorial</groupId>
<artifactId>estutorial</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>elasticsearch-rest-high-level-client</artifactId>
<version>6.4.2</version>
</dependency>
<dependency>
<groupId>org.elasticsearch.client</groupId>
<artifactId>transport</artifactId>
<version>6.4.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.logging.log4j/log4j-core -->
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.11.1</version>
</dependency>
</dependencies>
</project>
My pom.xml for the new maven project that tries to reference the lib for the above pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<properties>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.source>1.8</maven.compiler.source>
</properties>
<groupId>sth</groupId>
<artifactId>sth</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>estutorial</groupId>
<artifactId>estutorial</artifactId>
<version>1.0</version>
<scope>system</scope>
<systemPath>/home/dell/.m2/repository/estutorial/estutorial/1.0-SNAPSHOT/estutorial-1.0-SNAPSHOT.jar
</systemPath>
</dependency>
</dependencies>
</project>
So, if I understand your steps, your dependency declaration in your referencing application uses a direct classpath to the jar file in your local repository? If so, this is unusual. You shouldn't need to know direct file locations for any of your dependencies of a Maven project. What you should be doing.
In the referenced project (that which requires the Elasticsearch library), it's pom.xml file would defined the elasticsearch dependency itself. This should follow maven standards for dependency declaration (groupId, artifactId and artifactVerion). If you don't have the elasticsearch artifact, maven will attempt to find it and store it in your local repository. You shouldn't have to have any path in your pom.xml file.
When you install the referenced project, it will install into your local repostory both the JAR file and the pom.xml.
In the referencing project, you should define the dependency to your referenced artifact in it's pom file. Same format: groupId, artifactId and artifactVersion. You shouldn't need to provide a specific path. What maven will do is find your referenced jar, but also use the installed POM.xml file for the referenced jar to find the transitive dependencies and include them in your classpath.
From what you've described, your dependency declarations aren't correct. If you can provide your POM file more details can be provided. Otherwise, review the maven intro to dependencies.
No. mvn install is a nearly useless command. It stuffs a jar file into your local repository, for subsequent use by other maven builds. You use the term 'path'. If you run mvn install:install-file to put a jar into your local repo under some coordinates, you can reference those coordinates from another pom; but it will generally lead to future problems as compare to deploying the jar into a proper repository manager.
I have created the sample maven project and it executes well as expected, however I would like to know the location of JUnit library.
I tried to find it in the local repository and my project path but I do not find the one.
pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.maven.sample</groupId>
<artifactId>sampleproject</artifactId>
<packaging>jar</packaging>
<version>1.0-SNAPSHOT</version>
<name>sampleproject</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
Maven version: 3.3.9.
The file is certainly in your Maven cache, in the .m2/repository/junit/junit/3.8.1 folder, note the pattern: .m2/repository/<groupId>/<artifactId>/<version>
If you really want to have it automatically generated by Maven, use the Maven Dependency Plugin and its build-classpath goal.
From the command line on your project run:
mvn dependency:build-classpath
It will generate as part of the build output a list of paths for all the declared dependencies, so you will be sure where to look for.
Additionally, you can use the mdep.outputFile option to have it written to a file:
mvn dependency:build-classpath -Dmdep.outputFile=classpath.txt
I am having trouble importing spring framework into eclipse. I have downloaded spring but am unable to import it. Can anyone help or direct me to a web page that can do so?
You can either follow this tutorial:
http://www.tutorialspoint.com/spring/spring_hello_world_example.htm
or use the spring eclipse plugin (you can find it in eclipse under Help/eclipse marketplace and search for it)
or you can use a tool to manage your dependencies like maven.
It wouldn't be a bad idea to get familiar with a dependency manager like Maven. For use in Eclipse there is a nice plugin M2Eclipse. The pom.xml file is what you use to specify your dependencies, and then when you build with Maven it resolves everything for you and downloads automatically anything it needs. This is the example pom.xml file from the Maven installation instructions:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mycompany.app</groupId>
<artifactId>my-app</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>Maven Quick Start Archetype</name>
<url>http://maven.apache.org</url>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.8.2</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
The dependency for the core Spring Framework is
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.1.6.RELEASE</version>
</dependency>
And generally you can find the pom.xml dependency specifications at the Maven Repository. Might seem a little overdone for simply getting Spring into Eclipse, but once you have it set up it is then a snap to add more dependencies down the road, all you do is add the appropriate item to the pom.xml file.
I'm trying to use a SimpleMongoBolt from storm-contrib. I downloaded the source, entered the storm-contrib-mongo directory and ran mvn package and mvn install. Everything worked fine and IntelliJ was able to resolve things while coding. When I try to build my project, however, it tries to find a pom for this library on an external repository. When it can't find it, it fails. What do I need to do to fix this?
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>StormTest</groupId>
<artifactId>StormTest</artifactId>
<version>1.0</version>
<packaging>jar</packaging>
<name>StormTest</name>
<repositories>
<repository>
<id>clojars.org</id>
<url>http://clojars.org/repo</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>storm</groupId>
<artifactId>storm</artifactId>
<version>0.7.2</version>
<scope>Test</scope>
</dependency>
<dependency>
<groupId>com.rapportive</groupId>
<artifactId>storm-amqp-spout</artifactId>
<version>0.1.1</version>
</dependency>
<dependency>
<groupId>com.rapportive</groupId>
<artifactId>storm-json</artifactId>
<version>0.0.1</version>
</dependency>
<dependency>
<groupId>storm</groupId>
<artifactId>storm-contrib-mongo</artifactId>
<version>0.1-SNAPSHOT</version>
</dependency>
</dependencies>
</project>
You can try to check if you have proper dependencies defined in your project pom and compare them to storm artifact one. groupId, artifactId and version must be the same or Maven will try to download it from external repository and probably failed as it has never been installed on any public Maven repo.
When you install your artifact, it goes to user-directory/.m2/repostiory/group/id/path/*artifact/id/path*/version.
For your storm-amqp-spout you should have it in:
user-directory/.m2/repository/com/rapportive/storm-amqp-spout/0.1.1 folder.
There you should have few files:
jar itself (if it was packaged as jar file).
pom.xml file (the same you created for your project and you used to built and install it).
optionally sha1 files for both above.
If you don't have them, you probably made some mistake installing the artifact into repository. You can try to install it again or manually create pom just copying it from artifact source directory.
If there's correct pom.xml, I don't really have idea as I have never worked with IntelliJ (idea? ;)).
SimpleMongoBolt in Storm-Contrib was actually out of date. I updated the module myself and submitted a pull request, which has yet to be merged. Currently you can retrieve the updated code from my Storm-Contrib fork.