无法自动装配字段：private com.jio.asp.service.MongoDBBussinessDelegate

Question

自动装配MongoDBBussinessDelegate时出错 如果我将MongoDBBussinessDelegate初始化为类对象，则获取空指针异常。 我试图在控制器中自动装载Mongotemplate，但也得到了同样的错误。

错误

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mongoDBController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.jio.asp.service.MongoDBBussinessDelegate com.jio.asp.controller.MongoDBController.mongoDBBussinessDelegate; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mongoDBBussinessDelegate': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.data.mongodb.core.MongoTemplate com.jio.asp.service.MongoDBBussinessDelegate.mongoTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.data.mongodb.core.MongoTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:703)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4809)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5251)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
    at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:725)
    at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:701)
    at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:717)
    at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:940)
    at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1816)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.jio.asp.service.MongoDBBussinessDelegate com.jio.asp.controller.MongoDBController.mongoDBBussinessDelegate; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mongoDBBussinessDelegate': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.data.mongodb.core.MongoTemplate com.jio.asp.service.MongoDBBussinessDelegate.mongoTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.data.mongodb.core.MongoTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 26 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'mongoDBBussinessDelegate': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.data.mongodb.core.MongoTemplate com.jio.asp.service.MongoDBBussinessDelegate.mongoTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.data.mongodb.core.MongoTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1017)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    ... 28 more
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private org.springframework.data.mongodb.core.MongoTemplate com.jio.asp.service.MongoDBBussinessDelegate.mongoTemplate; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.data.mongodb.core.MongoTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 39 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.springframework.data.mongodb.core.MongoTemplate] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1103)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:963)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:858)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    ... 41 more

控制器

package com.jio.asp.controller;


import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.jio.asp.domain.Message;
import com.jio.asp.model.Person;
import com.jio.asp.service.MongoDBBussinessDelegate;

@RestController
public class MongoDBController {

    @Autowired
    private MongoDBBussinessDelegate mongoDBBussinessDelegate;


    @RequestMapping("/")
    @ResponseBody
    public String welcome(@RequestBody Map<String, String> user) {//Welcome page, non-rest
    //  MongoDBBussinessDelegate mongoDBBussinessDelegate = new MongoDBBussinessDelegate();
        //Person person = new Person();
        //person.setId("2");
        //person.setName("Raj");
        //m.addPerson(person);
        List<Person> lperson = mongoDBBussinessDelegate.listPerson();
        //m.addPerson(user);
        //System.out.println(mongoTemplate.getCollectionNames());
        return "done";
    }

    @RequestMapping("/hello/{player}")
    public Message message(@PathVariable String player) {//REST Endpoint.

        Message msg = new Message(player, "Hello " + player);
        return msg;
    }


}

服务

package com.jio.asp.service;

import java.util.List;
import java.util.Map;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.stereotype.Service;

import com.jio.asp.model.Person;
import com.mongodb.BasicDBObject;
import com.mongodb.DBCollection;
import com.mongodb.MongoClient;

@Service
public class MongoDBBussinessDelegate {

    @Autowired
    private MongoTemplate mongoTemplate;

    public static final String COLLECTION_NAME = "users";

    public void addPerson(Map<String, String> user) {
    /*  if (!mongoTemplate.collectionExists(Person.class)) {
            mongoTemplate.createCollection(Person.class);
        }*/ 
        //System.out.println(mongoTemplate.);

        DBCollection col = mongoTemplate.getCollection(COLLECTION_NAME);
        /*Map<String,String> map = new HashMap<>();
        map.put("username", "nishant");
        map.put("pass", "pass ho gya");*/
        BasicDBObject obj = new BasicDBObject(user);


        col.insert(obj);
        //person.set_id(UUID.randomUUID().toString());
        //mongoTemplate.insert(person, COLLECTION_NAME);
        //mongoTemplate.save(person,"person");
    }

    public List<Person> listPerson() {
        return mongoTemplate.findAll(Person.class,COLLECTION_NAME);
    }

    public void deletePerson(Person person) {
        mongoTemplate.remove(person, COLLECTION_NAME);
    }

    public void updatePerson(Person person) {
        mongoTemplate.insert(person, COLLECTION_NAME);      
    }
    public static void main(String [] args){

        MongoClient m = new MongoClient("localhost");
        System.out.println(m.getDatabaseNames());
        MongoTemplate t = new MongoTemplate(m, "aadhaar");
        System.out.println(t.getCollectionNames());
        /*DBCollection col = t.getCollection("users");
        Map<String,String> map = new HashMap<>();
        map.put("username", "nishant");
        map.put("pass", "pass ho gya");
        BasicDBObject obj = new BasicDBObject(map);


        col.insert(obj);*/

//      System.out.println(t.findAll(Person.class, COLLECTION_NAME));


    }
}

Dispatcher servlet

 <beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mongo="http://www.springframework.org/schema/data/mongo"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
http://www.springframework.org/schema/data/mongo
http://www.springframework.org/schema/data/mongo/spring-mongo-1.0.xsd">
 <context:component-scan base-package="com.jio.asp.controller" />
  <context:component-scan base-package="com.jio.asp.domain" />

  <context:component-scan base-package="com.jio.asp.model" />

  <context:component-scan base-package="com.jio.asp.service" />

  <bean id="mongo" class="com.mongodb.MongoClient">
    <constructor-arg  name="host" value="127.0.0.1" />

</bean>
<bean id="mongoTemplate" class="org.springframework.data.mongodb.core.MongoTemplate">
     <constructor-arg name="mongo" ref="mongo" />
     <constructor-arg name="databaseName" value="aadhaar" />
</bean>
</beans>