Autowired 为空且不适用于 Jersey + Spring

Question

I have problem figuring out why My Jersey RESTful entry point can't find the Spring Bean that I configure when the app server starts. It kept getting NullPointerException after trying from

• Spring DI - Autowired property is null in a REST service
• NullPointerException on @Autowired attribute with Jersey and Spring for REST service
• @Autowired is not working with jersey and spring
• Integrating both spring mvc and Jersey, getting a null pointer when viewing a jersey endpoint
• Jersey 2 + Spring: @Autowired is null

Web.xml

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/applicationContext*.xml</param-value>
</context-param>
<listener>
    <listener-class>
        org.springframework.web.context.ContextLoaderListener
    </listener-class>
</listener> 

<servlet>
    <servlet-name>jersey-serlvet</servlet-name>
    <servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
    <init-param>
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>com.testing.resource</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

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

Spring-context.xml

<context:annotation-config />
<context:component-scan base-package="com.testing.config, com.testing.repository, com.testing.workflow" />

<bean id="propertyConfigurer"
    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location">
        <value>classpath:jdbc.properties</value>
    </property>
</bean>

Jersey servlet entry point

@Component
@Produces(MediaType.APPLICATION_JSON)
@Path("/{userId}/items")
public class UserResource
{
  @Autowired
  private UserWorkFlow userWorkFlow;

  @GET
  public Response getAllItems(@PathParam("userId") String userId)
  {
    // ** NullPointerException here complains about the UserWorkFlow 
    return Response.status(200).entity(userWorkFlow.getItemsFor(userId)).build();
  }
}

Service layer

I also tried to make an interface for this but it didn't work.

@Service
public class UserWorkFlow
{
  @Autowired
  private AllItems allItems;

  public List<Item> getItemsFor(String id)
  {
    return allItems.getItemsFor(id);
  }
}

Repository and DAO

@Repository
public class AllItems
{
  @Autowired
  private ItemSql itemSql;

  public List<Item> getItemsFor(String id)
  {
    return itemSql.getAllItemsFor(id);
  }
}

MyBatis Mapper (this has a XML associated with it)

public interface UserSql
{
  List<Item> getAllItemsFor(@Param("userId") String userId);
} 

I also changed to com.sun.jersey from org.glassfish.jersey but didn't work. I am running out of ideas what could be wrong. Can anyone spot what did I do wrong ?

Answer 1

The link I provided for your previous question had links to four fully working examples. You could have easily just grabbed one of the examples and built on top of it.

I will just walk you through one of the examples. Maybe it was too hard to follow. I will use the Jersey 2.x with Spring XML config .

First , make sure you have the dependencies (only showing versions to ones not shown in the pom)

• jersey-container-servlet: 2.22.1
• spring-web: 3.2.3.RELEASE
• commons-logging
• jersey-spring3: 2.22.1 . (Notice the snapshot project uses jersey-spring*4* . This is not yet released, and will be released in the next Jersey release)

Second , make sure your web.xml is in order

Third , add your applicationContext.xml to the project class-path.

Fouth , the MyApplication class listed in the previous web.xml.

If you follow the example to the T, you will have a working example. It may not be the exact way you want to configure your Spring components, but you will have a working example you can build off of and tweak around to see what works and what doesn't. When you get more comfortable, you can see the other examples (in the first link of this answer) for other configuration styles/options.

Answer 2

我使用 SpringBeanAutowiringSupport 扩展了 ServiceImpl 和 DAOImpl 类，它解决了我的自动装配空指针异常。

Answer 3

Here you can create instance of that service and access the methods of the service. I think this is the simplest way.

UserService user = new UserService();
user.saveUser();