spring boot mongodb 复制集、主从实现

谁践踏了优雅 2022-05-27 12:37 336阅读 0赞

下面的实现方式比较死板，而且不优雅，还要主动的区分读写操作，使用主库还是从库，建议阅读新博客，[SpringBoot对MongoDB副本集(读写分离)实现][SpringBoot_MongoDB]

1.上篇文章简单的介绍了Mongodb，和做了一个简单的SpringBoot - Mongodb单机实现，本文将介绍 SpringBoot mongodb replica set复制集读写分离的实现，主库：Primary ， 从库：Secondary  
复制主要用于备份、灾难恢复和读写分离，可以应对更多的读操作，当主库挂了可以从副本集中选一个主节点，更多作用请自行百度，怎么搭建复制集请参考我之前的 [Mongodb安装与设置副本集 二][Mongodb_] 教程

2.spring boot 项目 Pom.xml中添加 spring-boot-starter-data-mongodb 包引用

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

3.在application.properties中配置连接信息(使用yaml配置比较优雅，但我配置后未能实现连接)

spring.data.mongodb.primary.host=192.168.68.128
    spring.data.mongodb.primary.port=27017
    spring.data.mongodb.primary.database=test
    spring.data.mongodb.primary.username=admin
    spring.data.mongodb.primary.password=admin
    
    spring.data.mongodb.secondary.host=192.168.68.129
    spring.data.mongodb.secondary.port=27017
    spring.data.mongodb.secondary.database=test
    spring.data.mongodb.secondary.username=admin
    spring.data.mongodb.secondary.password=admin

4.创建一个实体 User ,重写toString()方法，并在类上注解 @Document(collection = “user”) ，表名

@Document(collection = "user")
    public class User {
    
        private Long mid;
        private String userName;
        private String passWord;
    
        @Override
        public String toString() {
            return "User{" +
                    "mid=" + mid +
                    ", userName='" + userName + '\'' +
                    ", passWord='" + passWord + '\'' +
                    '}';
        }
        //Getter Setter....
    }

5.重点–创建一个抽象类 AbstractMongoConfig.class ， 创建一个主库配置类 PrimaryMongoConfig.class 和一个从库配置类 SecondaryMongoConfig.class 继承抽象类，重写 getMongoTemplate() 方法，用户返回 MongoTemplate 对象

public abstract class AbstractMongoConfig {
    
        // Mongo DB Properties
        private String host, database, username, password;
        private int port;
    
        /*
         * Method that creates MongoDbFactory Common to both of the MongoDb
         * connections
         */
        public MongoDbFactory mongoDbFactory() throws Exception {
            String url = "mongodb://"+username+":"+password+"@"+host+":"+port+"/"+database;
            MongoClientURI uri = new MongoClientURI(url);
            return new SimpleMongoDbFactory(new MongoClient(uri),database);
        }
    
        /*
         * Factory method to create the MongoTemplate
         */
        abstract public MongoTemplate getMongoTemplate() throws Exception;
    
        //host, database, username, password Getter Setter....
    }

@Configuration
    //在application.properties中查找 spring.data.mongodb.primary 开头的配置信息
    @ConfigurationProperties(prefix = "spring.data.mongodb.primary") 
    public class PrimaryMongoConfig extends AbstractMongoConfig {
    
        /**
         * Implementation of the MongoTemplate factory method
         * @Bean gives a name (primaryMongoTemplate) to the created MongoTemplate instance
         * @Primary declares that if MongoTemplate is autowired without providing a specific name,
         * this is the instance which will be mapped by         default
         */
        @Primary
        @Override
        public @Bean(name = "primaryMongoTemplate") MongoTemplate getMongoTemplate() throws Exception {
            return new MongoTemplate(mongoDbFactory());
        }
    }

@Configuration  
    //在application.properties中查找 spring.data.mongodb.secondary开头的配置信息
    @ConfigurationProperties(prefix = "spring.data.mongodb.secondary")  
    public class SecondaryMongoConfig extends  AbstractMongoConfig {
    
        /**
         * Implementation of the MongoTemplate factory method
         * @Bean gives a name (primaryMongoTemplate) to the created MongoTemplate instance
         * Note that this method doesn't have @Primary
         */
        @Override
        public @Bean(name = "secondaryMongoTemplate") MongoTemplate getMongoTemplate() throws Exception {
            return new MongoTemplate(mongoDbFactory());
        }
    }

6.UserDaoImpl类(省略了UserDao接口类)，使用配置类，获取 MongoTemplate

@Repository
    public class UserDaoImpl implements UserDao{
    
        // Using MongoTemplate for primary database
        @Autowired
        @Qualifier(value = "primaryMongoTemplate") //和上面配置类中的Bean（name）的名字对应
        protected MongoTemplate primaryMongoTemplate;
    
        // Using mongoTemplate for secondary database
        @Autowired
        @Qualifier(value = "secondaryMongoTemplate")//和上面配置类中的Bean（name）的名字对应
        protected MongoTemplate secondaryMongoTemplate;
    	
    	//主库存
        @Override
        public void savePrimary(User user) {
            primaryMongoTemplate.save(user);
        }
    	//从库存
        @Override
        public void saveSecondary(User user) {
            secondaryMongoTemplate.save(user);
        }
    	//从库读
        @Override
        public User findUserByUserName(String userName) {
            Query query = new Query();
            query.addCriteria(Criteria.where("userName").is(userName));
            return secondaryMongoTemplate.findOne(query,User.class);
        }
    
    }

7.测试，在测试类中运行如下代码：

//1.测试主库存
    @Test
    public void testSavePrimary() throws Exception {
    	User pUser = new User();
    	pUser.setMid(11L);
    	pUser.setUserName("primary");
    	pUser.setPassWord("123456");
    	userDao.savePrimary(pUser);
    }
    //2.测试从库存
    @Test
    public void testSaveSecondary() throws Exception {
    	User pSecond = new User();
    	pSecond.setMid(12L);
    	pSecond.setUserName("secondary");
    	pSecond.setPassWord("123456");
    	userDao.savePrimary(pSecond);
    }
    //3.从库读
    @Test
    public void testFindUser() throws Exception {
    	User pSecond = userDao.findUserByUserName("secondary");
    	System.out.println(pSecond.toString());
    }

8.测试结果正确的保存和读取出来了，主库-从库保存的数据，从库读取的数据直接用toString()方法打印到控制台了：  
![这里写图片描述][70]  
![这里写图片描述][70 1]

实现读写分离还有另外一个方式：使用 lombok和spring-boot-autoconfigure 包，但我未实现出来，供大家参考和百度。

最后总结，此方式还不是太优雅，只能算是一个简单实现，遗留问题：要是有多个从库该怎么办，在配置文件中配置多个数据源？然后写多个从库配置类？调用的时候再写一个轮询方法，用来获取MongoTemplate？这些都是应该考虑的问题，现在的方式还不够优雅。。。有待研究与改进。希望那位大大指教指教

[SpringBoot_MongoDB]: https://blog.csdn.net/zhuyu19911016520/article/details/82998162
[Mongodb_]: https://blog.csdn.net/zhuyu19911016520/article/details/79889923
[70]: /images/20220527/4f58df6736f54029bb8f89cffa58800f.png
[70 1]: /images/20220527/f3f72a3f5db4406384beb4baa95d9443.png