Java Rest Intro - JAR

 

https://stackoverflow.com/questions/39343021/how-to-turn-my-jersey-rest-api-into-an-executable-jar

 

How to turn my Jersey REST API into an executable JAR?

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I am using Jersey, Maven; and could use Jetty, Tomcat or J2EE Preview (is that embeddable?).

1. What is the easiest way to port my REST API as a standalone/executable JAR?
2. Can I do it without Spring Boot?

rest jersey executable

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edited Sep 6 '16 at 11:41 Cássio Mazzochi Molin 30.2k953104

asked Sep 6 '16 at 7:28 Raúl 1,05731633

What is J2ee Preview? – Cássio Mazzochi Molin Sep 6 '16 at 8:00

Eclipse provided lightweight server. – Raúl Sep 6 '16 at 8:01

It could be achieved with Spring Boot and Tomcat embedded. – Cássio Mazzochi Molin Sep 6 '16 at 8:04

1

Thank you. How about without Spring boot? – Raúl Sep 6 '16 at 8:05

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Follow these steps to create a standalone application with Jersey and Tomcat:

Adding Maven dependencies

Add the following dependencies to your pom.xml:

<properties>
    <tomcat.version>8.5.4</tomcat.version>
    <jersey.version>2.23.2</jersey.version>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<dependencies>
    <dependency>
        <groupId>org.apache.tomcat.embed</groupId>
        <artifactId>tomcat-embed-core</artifactId>
        <version>${tomcat.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat.embed</groupId>
        <artifactId>tomcat-embed-jasper</artifactId>
        <version>${tomcat.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>tomcat-jasper</artifactId>
        <version>${tomcat.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>tomcat-jasper-el</artifactId>
        <version>${tomcat.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>tomcat-jsp-api</artifactId>
        <version>${tomcat.version}</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet</artifactId>
        <version>${jersey.version}</version>
    </dependency>
</dependencies>

Adding Maven plugins

Add the following plugins to your pom.xml:

<build>
    <finalName>tomcat-embedded-sample</finalName>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.5.1</version>
            <inherited>true</inherited>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-shade-plugin</artifactId>
            <version>2.4.3</version>
            <configuration>
                <finalName>tomcat-embedded-sample-${project.version}</finalName>
            </configuration>
            <executions>
                <execution>
                    <phase>package</phase>
                    <goals>
                        <goal>shade</goal>
                    </goals>
                    <configuration>
                        <transformers>
                            <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                <mainClass>com.example.launch.Launcher</mainClass>
                            </transformer>
                        </transformers>
                    </configuration>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Creating a launcher class

Define a launcher class as following:

public class Launcher {

    public static void main(String[] args) throws Exception {
        new Launcher().start();
    }

    public void start() throws Exception {

        String contextPath = "";
        String appBase = ".";
        String port = System.getenv("PORT");
        if (port == null || port.isEmpty()) {
            port = "8080";
        }

        Tomcat tomcat = new Tomcat();
        tomcat.setPort(Integer.valueOf(port));
        tomcat.getHost().setAppBase(appBase);
        Context context = tomcat.addWebapp(contextPath, appBase);

        Tomcat.addServlet(context, "jersey-container-servlet", 
                            new ServletContainer(resourceConfig()));
        context.addServletMapping("/api/*", "jersey-container-servlet");

        tomcat.start();
        tomcat.getServer().await();
    }

    private ResourceConfig resourceConfig() {
        return new JerseyConfiguration();
    }
}

Defining Jersey configuration

Create a class to configure your Jersey application:

public class JerseyConfiguration extends ResourceConfig {

    public JerseyConfiguration() {
        packages("com.example");
    }
}

Creating resource classes

Define your resource class. The following is just an example:

@Path("hello")
public class HelloWorldResource {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public Response helloWorld() {
        return Response.ok("Hello World").build();
    }
}

Compiling and running the application

To compile and run the application, follow these steps:

• Open a command line window or terminal.
• Navigate to the root directory of the project, where the pom.xml resides.
• Compile the project: mvn clean compile.
• Package the application: mvn package.
• Look in the target directory. You should see a file with the following or a similar name: tomcat-embedded-sample-1.0-SNAPSHOT.jar.
• Change into the target directory.
• Execute the JAR: java -jar tomcat-embedded-sample-1.0-SNAPSHOT.jar.
• The application is available at http://localhost:8080/api/hello.

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edited Sep 6 '16 at 12:25

answered Sep 6 '16 at 8:42 Cássio Mazzochi Molin 30.2k953104

I thought 'maven-shade-plugin' would be required in the <build> section of pom. Isn't it? – Raúl Sep 6 '16 at 10:59

@Raúl I don't think so. I managed to run it without any additional plugins. – Cássio Mazzochi Molin Sep 6 '16 at 11:02

1

Don't use the assembly plugin. It will leave out required META/services files. Instead use the shade plugin that will concatenate these files. See this post – peeskillet Sep 6 '16 at 11:46

@peeskillet That's an interesting advice. Thanks for pointing it. – Cássio Mazzochi Molin Sep 6 '16 at 11:51

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up vote2down vote

Follow these steps to create a standalone application with Jersey and Jetty: Adding Maven dependencies Add the following dependencies to your pom.xml: <properties> <jetty.version>9.3.11.v20160721</jetty.version> <jersey.version>2.23.2</jersey.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-server</artifactId> <version>${jetty.version}</version> </dependency> <dependency> <groupId>org.eclipse.jetty</groupId> <artifactId>jetty-servlet</artifactId> <version>${jetty.version}</version> </dependency> <dependency> <groupId>org.glassfish.jersey.containers</groupId> <artifactId>jersey-container-servlet</artifactId> <version>${jersey.version}</version> </dependency> <dependency> <groupId>org.glassfish.jersey.containers</groupId> <artifactId>jersey-container-jetty-servlet</artifactId> <version>${jersey.version}</version> </dependency> </dependencies> Adding Maven plugins Add the following plugins to your pom.xml: <build> <finalName>jetty-embedded-sample</finalName> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.5.1</version> <inherited>true</inherited> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-shade-plugin</artifactId> <version>2.4.3</version> <configuration> <finalName>jetty-embedded-sample-${project.version}</finalName> </configuration> <executions> <execution> <phase>package</phase> <goals> <goal>shade</goal> </goals> <configuration> <transformers> <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"> <mainClass>com.example.launch.Launcher</mainClass> </transformer> </transformers> </configuration> </execution> </executions> </plugin> </plugins> </build> Creating a launcher class Define a launcher class as following: public class Launcher { public static void main(String[] args) throws Exception { new Launcher().start(); } public void start() throws Exception { String port = System.getenv("PORT"); if (port == null || port.isEmpty()) { port = "8080"; } Server server = new Server(Integer.valueOf(port)); ServletContextHandler context = new ServletContextHandler(server, "/"); ServletHolder servlet = new ServletHolder(new ServletContainer(resourceConfig())); context.addServlet(servlet, "/api/*"); try { server.start(); server.join(); } finally { server.destroy(); } } private ResourceConfig resourceConfig() { return new JerseyConfiguration(); } } Defining Jersey configuration Create a class to configure your Jersey application: public class JerseyConfiguration extends ResourceConfig { public JerseyConfiguration() { packages("com.example"); } } Creating resource classes Define your resource class. The following is just an example: @Path("hello") public class HelloWorldResource { @GET @Produces(MediaType.TEXT_PLAIN) public Response helloWorld() { return Response.ok("Hello World").build(); } } Compiling and running the application To compile and run the application, follow these steps: Open a command line window or terminal. Navigate to the root directory of the project, where the pom.xml resides. Compile the project: mvn clean compile. Package the application: mvn package. Look in the target directory. You should see a file with the following or a similar name: jetty-embedded-sample-1.0-SNAPSHOT.jar. Change into the target directory. Execute the JAR: java -jar jetty-embedded-sample-1.0-SNAPSHOT.jar. The application is available at http://localhost:8080/api/hello.