使用 JAX-RS tomcat 服务器返回“请求的资源不可用”的 REST

Question

I was following short tutorial on creating REST api using JAX-RS. I am using Tomcat server v7.0. When I run the application on the server I get error 404-requested resource is not available. The project is Maven based, and my pom.xml file includes the following line

  <properties>
    <failOnMissingWebXml>false</failOnMissingWebXml>
 </properties>

I do not have web.xml file as a result. That was how the tutorial was achieved. I do not have index.html/jsp file. I have created two classes RESTconfig.java and BookResources.java

...import statements 
@ApplicationPath("api")
public class RESTconfig extends Application {

}

...import statements
@Path("books")
public class BookResources {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String books() {
        return "Hello world";
    }
}

My pom.xml file looks like this

<groupId>com.dere</groupId>
  <artifactId>myrest</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
    <properties>
    <failOnMissingWebXml>false</failOnMissingWebXml>
  </properties>
  <dependencies>
  <dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>7.0</version>
    <scope>provided</scope>
 </dependency>

Once I run the application on the server and go to http://localhost:9090 I am able to see Tomcat home page, but if try to get data http://localhost:9090/myrest/api/books I get the 404 error, ie requested resource is not available, I mentioned above. Most of the examples or usage I saw online involve using web.xml and providing root of the application and using a servlet. This is my first exposure to building REST api. I may have misunderstood the whole thing or I skipped some step. I look forward for your help. I am using Eclipse Photon for Java EE

Answer 1

Look at this

<dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>7.0</version>
</dependency>

This is nothing more than basically a bunch of interfaces for the EE spec. There is no implementation. Java EE servers will have the implementation. Tomcat is not an EE server. The only part of the EE spec it will definitely have the implementation for is Servlets and JSP (the web profile). If you want an EE server, checkout Glassfish or Wildfly.

You are trying to work with the JAX-RS spec, where Tomcat for sure by default does not have an implementation for. So you need to add that implementation. The easiest implementation, IMO to get started with, is Jersey. You can simply add this dependency

<dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>2.25.1</version>
</dependency>

and it will get you up and running. Keep the Jersey User Guide handy. It will come in use.