Jersey Tutorials from Basics_问答_开发者_运维开发者技术经验分享

I am using Jersey 1.8 and the tutorials that I am referring are quiet old. Nothing works. I am referring to the tutorial given here

And get a class not found exception. as per the tutorial I made my Java Class as well as configured my web.xml. It shows me an exception and I am not getting a way to fix this. I would like to have a complete up to date tutorial for Jersey implementation. And if something is better than Jersey for REST implementation please suggest. I have rescently started with REST based web services and would appreciate if you can suggest me where to start from(I am only interested in REST). Below is the code that I wrote and compiled using eclipse.

Hello.java

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
@Path("/hello")
public class Hello {

    //This method prints the Plain Text
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String sayPlainTextHello()
    {
        return "Hello Jersey";
    }

    //This is the XML request output

    @GET
    @Produces(MediaType.TEXT_XML)
    public String sayXMLHello()
    {
        return "<?xml version=\"1.0\"?>" + "<hello> Hello Jersey" + "</hello>";
    }

    //This result is produced if HTML is requested

    @GET
    @Produces(MediaType.TEXT_HTML)
    public String sayHTMLHello()
    {
        return "<html> " + "<title>" + "Hello Jersey" + "</title>"
        + "<body><h1>" + "Hello Jersey" + "</body></h1>" + "</html> ";
    }

}

web.xml is as follows

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/java开发者_JS百科ee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>RESTFullApp</display-name>
  <servlet>
  <servlet-name>JerseyRESTService</servlet-name>
  <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer;</servlet-class>
  <init-param>
  <param-name>com.sun.jersey.config.property.packages</param-name>
  <param-value>RESTFullApp</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
  <servlet-name>JerseyRESTService</servlet-name>
  <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>
<!--  <welcome-file-list>-->
<!--    <welcome-file>index.html</welcome-file>-->
<!--    <welcome-file>index.htm</welcome-file>-->
<!--    <welcome-file>index.jsp</welcome-file>-->
<!--    <welcome-file>default.html</welcome-file>-->
<!--    <welcome-file>default.htm</welcome-file>-->
<!--    <welcome-file>default.jsp</welcome-file>-->
<!--  </welcome-file-list>-->
</web-app>

Noe the error I get while I try to run is

exception 

javax.servlet.ServletException: Servlet.init() for servlet JerseyRESTService threw exception
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    java.lang.Thread.run(Unknown Source)


root cause 

com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.
    com.sun.jersey.server.impl.application.RootResourceUriRules.<init>(RootResourceUriRules.java:99)
    com.sun.jersey.server.impl.application.WebApplicationImpl._initiate(WebApplicationImpl.java:1298)
    com.sun.jersey.server.impl.application.WebApplicationImpl.access$700(WebApplicationImpl.java:169)
    com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:775)
    com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:771)
    com.sun.jersey.spi.inject.Errors.processWithErrors(Errors.java:193)
    com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:771)
    com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:766)
    com.sun.jersey.spi.container.servlet.ServletContainer.initiate(ServletContainer.java:488)
    com.sun.jersey.spi.container.servlet.ServletContainer$InternalWebComponent.initiate(ServletContainer.java:318)
    com.sun.jersey.spi.container.servlet.WebComponent.load(WebComponent.java:609)
    com.sun.jersey.spi.container.servlet.WebComponent.init(WebComponent.java:210)
    com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:373)
    com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:556)
    javax.servlet.GenericServlet.init(GenericServlet.java:212)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    java.lang.Thread.run(Unknown Source)

You're not exactly following the tutorial. You changed bits here and there without actually understanding what they represents. In this particular case, according to the exception,

com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.

the following init param is wrong

<init-param>
   <param-name>com.sun.jersey.config.property.packages</param-name>
   <param-value>RESTFullApp</param-value>
</init-param>

It should refer to the package containing the services. Put your service in a package and specify that in the init param value. Jersey or not, using the default package is always a bad practice.

As to the tutorials, why don't you just read Jersey's own documentation? Jersey Wiki and Jersey User Guide.

Try the Jersey User Guide. It will pretty much always have the most up-to-date tutorial. As for the error, your web.xml declares that your resources classes will be in a package called "RESTFullApp". 1) That's a peculiar package name, and 2) I don't see a package declaration on your class.

Edit: For a working example, you check out my sample project on github. If you have git and maven, you can clone it and run it with

git clone git://github.com/zzantozz/testbed.git tmp
cd tmp
mvn jetty:run -pl basic-jersey

Then visit http://localhost:8080/basic-jersey/rest/test

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