Spring Cloud下SpringBoot与Spring Data JPA、Mongodb整合时注入mongoTemplate

最近在将之前遗留的一个数据服务项目从SSH移植到SpringBoot下，进行拆分作为单独的微服务进行运行。而在移植完成运行项目时，出现莫名异常，异常输出如下：

Description:

Field xxxxxxx_Repository in cn.cupid.service.impl.xxxxxxx_Service_Impl required a bean named 'mongoTemplate' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean named 'mongoTemplate' in your configuration.

很明显，报的异常时是没有为其中一个Service的实现类注入mongoTemplate。于是考虑是否是自己代码中疏忽了，经过反复检查代码无问题。进而这种异常是否只有这个Service会出现呢？将这个Service有关的类注释之后，进行测试这个异常仍然存在。这个时候就可以确定了，是整个项目中的mongoTemplate注入失败。回顾代码，mongoTemplate确实已经被自己手动注入过，而且在之前的项目中是证实注入mongoTempate是成功的。我采用的注入方式是在SpringBoot项目入口类进行注入，注入代码如下：

package cn.cupid;

import com.mongodb.MongoClient;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.data.mongo.MongoDataAutoConfiguration;
import org.springframework.boot.autoconfigure.mongo.MongoAutoConfiguration;
import org.springframework.cloud.client.circuitbreaker.EnableCircuitBreaker;
import org.springframework.cloud.client.discovery.EnableDiscoveryClient;
import org.springframework.cloud.client.loadbalancer.LoadBalanced;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.core.MongoTemplate;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.web.client.RestTemplate;


@ComponentScan(basePackages = {"cn.cupid.*"})
@EnableDiscoveryClient
@EnableScheduling
@EnableCircuitBreaker
@EnableMongoRepositories
public class DemoApplication {

    public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

    
	@Bean
	public MongoClient mongo() throws Exception {
		return new MongoClient("localhost", 27017);
	}

    //注入mongoTemplate
	@Bean
	public MongoTemplate getMongoTemplate() throws Exception{
		return new MongoTemplate(mongo(), databaseName);
	}


}

经过查阅资料进行反复测试，终于找到解放方法，注入mongoTemplate方式如下：

package cn.cupid.config;

import com.mongodb.MongoClient;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.core.MongoTemplate;

/**
 * @Author: cupid
 * Created by Cupid520 on 2019/1/16.
 * @Description:
 */
@Configuration
public class MongoConfig {

    @Bean
    public MongoClient mongoClient() {
        return new MongoClient("localhost", 27017);
    }

     @Bean
     public MongoTemplate mongoTemplate() {
        return new MongoTemplate(mongoClient(), "newdb");
    }


}

采用@Configuration注解方式，新建类进行注入，项目运行成功。

同样是注入，为什么后一种可以成功呢？按Spring加载Bean进行管理进行猜想，应该是前一种方式的mongoTemplate注入在Service类之后，所以导致项目运行失败。验证如下：

2019-01-16 21:44:07.442  INFO 9432 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
-------------DemoApplication init--------
---------MongoConfig------
2019-01-16 21:44:08.149  INFO 9432 --- [  restartedMain] org.mongodb.driver.cluster               : Cluster created with settings {hosts=[localhost:27017], mode=SINGLE, requiredClusterType=UNKNOWN, serverSelectionTimeout='30000 ms', maxWaitQueueSize=500}
2019-01-16 21:44:08.277  INFO 9432 --- [localhost:27017] org.mongodb.driver.connection            : Opened connection [connectionId{localValue:1, serverValue:11}] to localhost:27017
2019-01-16 21:44:08.282  INFO 9432 --- [localhost:27017] org.mongodb.driver.cluster               : Monitor thread successfully connected to server with description ServerDescription{address=localhost:27017, type=STANDALONE, state=CONNECTED, ok=true, version=ServerVersion{versionList=[2, 6, 9]}, minWireVersion=0, maxWireVersion=2, maxDocumentSize=16777216, logicalSessionTimeoutMinutes=null, roundTripTimeNanos=2441051}
---------xxxxxxxxxxxx_Impl init---------
-------------getMongoTemplate init--------
2019-01-16 21:44:09.835  WARN 9432 --- [  restartedMain] c.n.c.sources.URLConfigurationSource     : No URLs will be polled as dynamic configuration sources.
2019-01-16 21:44:09.835  INFO 9432 --- [  restartedMain] c.n.c.sources.URLConfigurationSource     : To enable URLs as dynamic configuration sources, define System property archaius.configurationSource.additionalUrls or make config.properties available on classpath.
2019-01-16 21:44:09.846  WARN 9432 --- [  restartedMain] c.n.c.sources.URLConfigurationSource     : No URLs will be polled as dynamic configuration sources.

很明显，猜想正确，顺利出坑。