Java 如何使用webservice调用DAO方法

我是JavaRESTfulWebService的新手，我已经在我的dao中编写了所需的方法，现在我想使用webservice调用这些方法。我尝试了下面提到的代码

Web.xml

<servlet>
    <servlet-name>jersey-servlet</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
   <!--  <init-param>
        <param-name>jersey.config.server.provider.packages</param-name>
         <param-value>com.demo.service</param-value>
    </init-param> -->
     <init-param>
        <param-name>javax.ws.rs.Application</param-name>
        <param-value>com.demo.service.MyApplication</param-value>
    </init-param>
</servlet>

<servlet-mapping>
    <servlet-name>jersey-servlet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

Java

public interface RestDao 
{
public String getempemailsearch(String name);
}

Java

@Repository
@Singleton
public class RestDaoImpl implements RestDao
{

 @Transactional(value="transactionManager")
 public String getempemailsearch(String name)
 {
   System.out.println("Hi This is MY DAO");
 }
}

Java

 package com.restfull.robert;
 import javax.ws.rs.core.MediaType;
 import com.sun.jersey.api.client.Client;
 import com.sun.jersey.api.client.ClientResponse;
 import com.sun.jersey.api.client.WebResource;


 public class RestClient {
  private final static String URI="http://localhost:8080/resttest/rest/endPoint/service/author";
public static void main(String args[]) {
    Client client=Client.create();
    WebResource webresource= client.resource(URI);
  /*        ClientResponse   clientresponse=webresource.get(ClientResponse.class);//get 
 */     
    ClientResponse clientresponse=webresource.accept(MediaType.TEXT_PLAIN).entity("arjun").post(ClientResponse.class);
    if(clientresponse.getStatus() == 200){
        String op=clientresponse.getEntity(String.class);
        System.out.println("Client Side OutPut "+op);
    }
 }

 }

在这一行我得到了空指针异常，我需要解决这个问题

String daoRes=dao.getempemailsearch(res); // Got Error NullPointer Exception

现在我得到了输出：

我是作家。。这就是我的测试目的 空指针异常 客户端输出异常

预期产出：

我是作家。。这就是我的测试目的 客户端输出Hi这是我的DAO

String daoRes=dao.getempemailsearch(res); // Got Error NullPointer Exception