无法通过@Autowired使用Spring将Solr服务器注入应用程序

我目前在尝试将bean中的solr服务器实例注入代码时遇到问题。我得到了一个

NullPointerException

，并检查了服务器实例本身并验证了它为null。我可以创建服务器而无需注入它

我的spring.xml文件声明bean如下：

<bean id="solrServer" class="org.apache.solr.client.solrj.impl.HttpSolrServer">`
     <constructor-arg index="0" value="${solr.serverUrl}" />
</bean>

<context:annotation-config />
<context:component-scan base-package="my.base.package" />

我试图注入这个bean的代码正在自动连接，如下所示：

34    @Component
35    public class GenericClassImpl implements GenericClass{
36  
37        @Autowired
38        private SolrServer solrServer;
39  
40        public String doQuery(String query){
41            try{          
42                    SolrQuery solrQuery = new SolrQuery(query);           
43                    QueryResponse rsp = solrServer.query(solrQuery);
44                    SolrDocumentList docs = rsp.getResults();
45          
46                    return docs.toString();
47            }catch(Exception e){
48                e.printStackTrace();
49            }
50        }
51    }

我尝试将

@限定符（“solrServer”）

与

@自动连线

一起使用，但也没有成功

这一切都是使用maven完成的，maven本身似乎没有任何问题。我得到的结果是

java.lang.NullPointerException
    at ...GenericClassImpl.doQuery(GenericClassImpl.java:43)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.sun.jersey.spi.container.JavaMethodInvokerFactory$1.invoke(JavaMethodInvokerFactory.java:60)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$TypeOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:185)
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)
    at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:288)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:108)
    at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:147)
    at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:84)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1483)
    at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1414)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1363)
    at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1353)
    at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:414)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537)
    at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:708)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
    at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
    at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
    at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
    at java.lang.Thread.run(Thread.java:662)

再说一次，如果我这样做的话

SolrServer solrServer = new HttpSolrServer(serverUrl);

代码工作正常，我可以在solr服务器上执行查询。 关于我做错了什么的任何想法都不会被注入

获取

GenericClassImpl

实例的代码为

public class GenericServiceImpl implements GenericService{

    protected GenericClass gc;

    @GET
    @Path({pathParam})
    public String doGet(@PathParam({pathParam}) String pathParam, 
                        @DefaultValue("*:*") @QueryParam("q") String query){

            gc = SearchFactory.getInstance().getGenericClass(pathParam);        
            return gc.doQuery(query);
        }
    }

而

搜索工厂

是

public class SearchFactory{

    private static SearchFactory instance;

    private SearchFactory(){}

    public static SearchFactory getInstance() {
        if (instance == null)
            instance = new SearchFactory();
        return instance;
    }

    public GenericClass getGenericClass(String type){

        GenericClass result = null;

        if(type.toLowerCase().equals("case1")){
            result = new GenericClassImpl1();
            return result;
        }
        else if(type.toLowerCase().equals("case2")){
            result = new GenericClassImpl2();
            return result;
        }
        else throw new Exception();
    }
}

---

GenericClassImpl1

和

GenericClassImpl2

扩展了

GenericClassImpl

，当前都是空的。

为了让

@Autowired

工作，您需要从Spring获取

GenericClassImpl

实例。如果不这样做，Spring将不会自动关联依赖项

不能使用

new

关键字实例化它们，也不能使用依赖项注入技术

您可以做的是保持对

ApplicationContext

的静态引用，然后在

getGenericClass

方法中从中提取相关bean的实例

---

正如Spring文档中所讨论的，这实际上是ServiceLocator模式的一个很好的用例。

您能给我们展示一下获取GenericClassImpl实例的代码吗？我刚刚添加了获取GenericClassImpl实例的代码。谢谢我最后做的是在SearchFactory、GenericClassImpl1和GenericClassImpl2类上添加一个组件，并对其中的新实例变量使用自动连线，然后返回这些私有变量，让spring处理它们的构造并能够管理它们的生命周期

public class SearchFactory{

    private static SearchFactory instance;

    private SearchFactory(){}

    public static SearchFactory getInstance() {
        if (instance == null)
            instance = new SearchFactory();
        return instance;
    }

    public GenericClass getGenericClass(String type){

        GenericClass result = null;

        if(type.toLowerCase().equals("case1")){
            result = new GenericClassImpl1();
            return result;
        }
        else if(type.toLowerCase().equals("case2")){
            result = new GenericClassImpl2();
            return result;
        }
        else throw new Exception();
    }
}