如何将Jetty和Jersey嵌入到我的Java应用程序中

Question

So I'm trying to embed jetty into my web application so that if I package it as a jar someone can just run the jar file without having to worry about configuring a server. However, I'm having some problems setting up my main class so that jetty can access my resource classes. I've looked at tutorials but they haven't given me exactly what I'm looking for. This is what I have so far.

package pojo;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

public class Main {

    public static void main(String[] args) throws Exception {
        Server server = new Server(8080);
        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.NO_SESSIONS);
        context.setContextPath("/");
        ServletHolder h = new ServletHolder(new DefaultServlet());
        h.setInitParameter("javax.ws.rs.Application","resources.DBCollection");
        context.addServlet(h, "/*");
        server.setHandler(context);
        server.start();
        server.join();
    }
}

And I'm trying to map it to this class:

package resources;


import java.util.ArrayList;
import java.util.List;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.UriInfo;

import pojo.Party;

@Path("/parties")
public class DBCollection {

    @Context
    UriInfo url;

    @Context
    Request request;

    String name;

    @GET
    @Produces({MediaType.APPLICATION_XML, MediaType.APPLICATION_JSON})
    public List<Party> getAllParties() throws Exception
    {
        List<Party> list = new ArrayList<Party>();
        list.addAll(DBConnection.getPartyCollection().values());
        return list;
    }

    @GET
    @Path("count")
    @Produces(MediaType.TEXT_PLAIN)
    public String getPartyCount() throws Exception
    {
        return String.valueOf(DBConnection.getPartyCollection().size());
    }

    @Path("{party}")
    public DBResource getParty(@PathParam("party")String party)
    {
        return new DBResource(url,request,party);
    }
}

Here's my POM file:

<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>PartyAPI</groupId>
    <artifactId>PartyAPIMaven</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>
        <dependency>
            <groupId>com.codahale.metrics</groupId>
            <artifactId>metrics-core</artifactId>
            <version>3.0.1</version>
        </dependency>
        <dependency>
            <groupId>com.sun.jersey</groupId>
            <artifactId>jersey-server</artifactId>
            <version>1.17.1</version>
        </dependency>

        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-server</artifactId>
            <version>9.0.0.RC0</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-servlet</artifactId>
            <version>9.0.0.RC0</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.jetty</groupId>
            <artifactId>jetty-servlets</artifactId>
            <version>9.0.0.RC0</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>eclipselink</artifactId>
            <version>2.6.0-SNAPSHOT</version>
        </dependency>

    </dependencies>
    <repositories>
        <repository>
            <id>oss.sonatype.org</id>
            <name>OSS Sonatype Staging</name>
            <url>https://oss.sonatype.org/content/groups/staging</url>
        </repository>
    </repositories>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-shade-plugin</artifactId>
                <version>1.6</version>
                <configuration>
                    <createDependencyReducedPom>true</createDependencyReducedPom>
                    <filters>
                        <filter>
                            <artifact>*:*</artifact>
                            <excludes>
                                <exclude>META-INF/*.SF</exclude>
                                <exclude>META-INF/*.DSA</exclude>
                                <exclude>META-INF/*.RSA</exclude>
                            </excludes>
                        </filter>
                    </filters>
                </configuration>
                <executions>
                    <execution>
                        <phase>package</phase>
                        <goals>
                            <goal>shade</goal>
                        </goals>
                        <configuration>
                            <transformers>
                                <transformer
                                    implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer" />
                                <transformer
                                    implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                                    <manifestEntries>
                                        <Main-Class>com.resteasy.Star.Main</Main-Class>

                                    </manifestEntries>

                                </transformer>
                            </transformers>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

Answer 1

A few things.

1. Jetty 9.0.0.RC0 is an old, not-yet stable, release candidate, consider upgrading to a stable, final release, such as 9.0.4.v20130625
2. You need something that will connect that Jax RS class into the servlet api. Usually done via a Servlet or some sort of initialization with your library of choice. (In you case Jersey)

In your example, you have only setup a DefaultServlet to serve static files, nothing has been configured to use your DBCollection object.

For Jersey, you'll need to configure the org.glassfish.jersey.servlet.ServletContainer and setup its servlet-mappings on a context of your choice.

Example:

package com.example;

import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

public class Main
{
    public static void main(String[] args)
    {
        Server server = new Server(8080);

        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.NO_SESSIONS);
        context.setContextPath("/");
        server.setHandler(context);

        ServletHolder jerseyServlet = context.addServlet(org.glassfish.jersey.servlet.ServletContainer.class, "/webapi/*");
        jerseyServlet.setInitOrder(1);
        jerseyServlet.setInitParameter("jersey.config.server.provider.packages","com.example");

        ServletHolder staticServlet = context.addServlet(DefaultServlet.class,"/*");
        staticServlet.setInitParameter("resourceBase","src/main/webapp");
        staticServlet.setInitParameter("pathInfoOnly","true");

        try
        {
            server.start();
            server.join();
        }
        catch (Throwable t)
        {
            t.printStackTrace(System.err);
        }
    }
}

This example adds the ServletContainer that jersey provides to the ServletContextHandler that Jetty uses to look up what to do based on the incoming request. Then it adds the DefaultServlet to handle any requests for content that Jersey does not handle (such as static content)

Answer 2

In case you want to completely manage the lifecycle of your DBCollection resource programmatically (eg you instantiate it yourself, do some setup/initialization etc), instead of having Jersey create the instance for you, you can use a ResourceConfig like such:

ServletContextHandler sch = new ServletContextHandler();
sch.setContextPath("/xxx");

TheResource resource = new TheResource();
ResourceConfig rc = new ResourceConfig();
rc.register(resource);

ServletContainer sc = new ServletContainer(rc);
ServletHolder holder = new ServletHolder(sc);
sch.addServlet(holder, "/*");

Server server = new Server(port);
server.setHandler(sch);
server.start();
server.join();

Note the line TheResource resource = new TheResource(); . Here we create our own instance of TheResource, and we can manipulate it at will now.