spring data 连接mongodb的两种方式

    <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-mongodb</artifactId>
            <version>2.1.4.RELEASE</version>
        </dependency>

  <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver-sync</artifactId>
            <version>${mongodb-driver-version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-mongodb</artifactId>
            <version>${spring-data-mongodb-version}</version>
            <scope>compile</scope>
        </dependency>

  public static MongoTemplate mongoTemplate;

    @Override
    public Object toClient() {
        if(mongoTemplate==null){
            mongoTemplate = new MongoTemplate(new SimpleMongoClientDatabaseFactory(url));
        }
        return mongoTemplate;
    }