使用NoSQL数据库

Posted 2021-03-14 hoo334

一、使用MongoDB持久化文档数据    

    有一些数据的最佳表现形式是文档，也就是说，不要把这些数据分散到多个表、节点或实体中，将这些信息收集到一个非规范化（也就是文档）的结构中更有意义。如果数据之间有明显的关联关系，文档数据库就不太适合了。

我们在一个购物订单系统中学习MongoDB。接下来我们要配置Spring Data MongoDB

package orders.config;

import com.mongodb.Mongo;
import com.mongodb.MongoClient;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.config.AbstractMongoConfiguration;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;

@Configuration
@EnableMongoRepositories(basePackages = "orders.db")
public class MongoConfig extends AbstractMongoConfiguration {

    @Override
    public Mongo mongo() throws Exception {
        return new MongoClient();
    }

    @Override
    protected String getDatabaseName() {
        return "OrdersDB";
    }
}

通过@EnableMongoRepository注解启用Spring Data 的自动化MongoDB repository生成功能，我们让配置类扩展AbstractMongoConfiguration并重载mongo()方法，getDatabaseName()方法，mongo()方法会直接返回一个MongoClient实例而不是声明MongoFactory bean 和MongoTemplate bean。使用MongoClient更加简单。这里需要一个运行在本地的MongoDB 服务器，MongoClient监听的默认的端口27017，如果需要更改端口在MongoClient构造方法中指定端口即可。

下面是Order类

package orders;

import org.springframework.data.annotation.Id;
import org.springframework.data.mongodb.core.mapping.Document;
import org.springframework.data.mongodb.core.mapping.Field;

import java.util.Collection;
import java.util.LinkedHashSet;

@Document
public class Order {

    @Id
    private String id;

    @Field("customer")
    private String customer;

    private String type;

    private Collection<Item> items = new LinkedHashSet<>();

    public String getId() {
        return id;
    }

    public String getCustomer() {
        return customer;
    }

    public void setCustomer(String customer) {
        this.customer = customer;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Collection<Item> getItems() {
        return items;
    }

    public void setItems(Collection<Item> items) {
        this.items = items;
    }
}

我们可以看到Order类使用了@Document注解，这样它就能借助MongoTemplate或自动生成的Repository进行持久化，其id属性上使用了@Id注解用来指定它作为文档的ID，除此之外，customer属性上使用了@Field注解，这样在文档持久化的时候customer属性会映射为customer的域。同时items属性它指的是订单中具体条目的集合，在传统的关系型数据库中，这些条目会在另一个数据表中，通过外键进行引用，items域上可能还会有使用JPA的@OneToMany注解。

下面是Item类，Item类本身没有任何注解。

package orders;
public class Item {

    private Long id;

    private Order order;

    private String product;

    private double price;

    private int quantity;

    public Long getId() {
        return id;
    }

    public Order getOrder() {
        return order;
    }

    public String getProduct() {
        return product;
    }

    public double getPrice() {
        return price;
    }

    public int getQuantity() {
        return quantity;
    }

    public void setProduct(String product) {
        this.product = product;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
}

我们定义OrderRepository扩展MongoRepository,它和Spring Data JPA一样，扩展了Repository的接口将会在运行时自动生成实现。

package orders.db;

import orders.Order;
import org.springframework.data.mongodb.repository.MongoRepository;
import org.springframework.data.mongodb.repository.Query;

import java.util.List;

public interface OrderRepository extends MongoRepository<Order,String> {
    List<Order> findByCustomer(String customer);

    List<Order> findByCustomerLike(String customer);

    List<Order> findByCustomerAndType(String customer,String type);

    List<Order> getByType(String type);

    @Query("{customer:‘Chuck Wagon‘}")
    List<Order> findChucksOrders();
}

下面是测试类

package orders;

import static org.junit.Assert.*;

import java.util.Arrays;
import java.util.List;

import orders.config.MongoConfig;
import orders.db.OrderRepository;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.core.MongoOperations;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@ContextConfiguration(classes=MongoConfig.class)
@RunWith(SpringJUnit4ClassRunner.class)
public class MongoDbTest {

   @Autowired
   private OrderRepository orderRepository;

   @Autowired MongoOperations mongoOps;
   
   @Before
   public void cleanup() {
      // Deleting all orders (just in case something is left over from a previous failed run)
      orderRepository.deleteAll();
   }
   
   @Test
   public void testMongoRepository() {
      assertEquals(0, orderRepository.count());
      Order order = createAnOrder();
      
      // Saving an order
      Order savedOrder = orderRepository.save(order);       
      assertEquals(1, orderRepository.count());
      
      // Finding an order by ID
      Order foundOrder = orderRepository.findOne(savedOrder.getId());
      assertEquals("Chuck Wagon", foundOrder.getCustomer());
      assertEquals(2, foundOrder.getItems().size());

      // Finding an order by a single field value
      List<Order> chucksOrders = orderRepository.findByCustomer("Chuck Wagon");
      assertEquals(1, chucksOrders.size());
      assertEquals("Chuck Wagon", chucksOrders.get(0).getCustomer());
      assertEquals(2, chucksOrders.get(0).getItems().size());

      // Finding an order by a single field value like
      List<Order> chuckLikeOrders = orderRepository.findByCustomerLike("Chuck");
      assertEquals(1, chuckLikeOrders.size());
      assertEquals("Chuck Wagon", chuckLikeOrders.get(0).getCustomer());
      assertEquals(2, chuckLikeOrders.get(0).getItems().size());

      // Finding an order by multiple field values
      List<Order> chucksWebOrders = orderRepository.findByCustomerAndType("Chuck Wagon", "WEB");
      assertEquals(1, chucksWebOrders.size());
      assertEquals("Chuck Wagon", chucksWebOrders.get(0).getCustomer());
      assertEquals(2, chucksWebOrders.get(0).getItems().size());

      List<Order> chucksPhoneOrders = orderRepository.findByCustomerAndType("Chuck Wagon", "PHONE");
      assertEquals(0, chucksPhoneOrders.size());

      // Finding an order by a custom query method
      List<Order> chucksOrders2 = orderRepository.findChucksOrders();
      assertEquals(1, chucksOrders2.size());
      assertEquals("Chuck Wagon", chucksOrders2.get(0).getCustomer());
      assertEquals(2, chucksOrders2.get(0).getItems().size());
      
      
      // Deleting an order
      orderRepository.delete(savedOrder.getId());
      assertEquals(0, orderRepository.count());     

   }

   private Order createAnOrder() {
      Order order = new Order();
      order.setCustomer("Chuck Wagon");
      order.setType("WEB");
      Item item1 = new Item();
      item1.setProduct("Spring in Action");
      item1.setQuantity(2);
      item1.setPrice(29.99);
      Item item2 = new Item();
      item2.setProduct("Module Java");
      item2.setQuantity(31);
      item2.setPrice(29.95);
      order.setItems(Arrays.asList(item1, item2));
      return order;
   }
   
}

二、使用Neo4j操作位图数据

    文档型数据库会将数据存储到粗粒度的文档中，图数据库会将数据存储到多个细粒度的节点中，这些节点之间通过关系建立关联。Spring Data Neo4j提供了将Java对象映射到节点和关联关系的注解、面向模板的Neo4j访问方式以及Repository‘实现的自动化生成功能。

配置Spring Data Neo4j的关键在于声明GraphDatabaseService bean 和启用Neo4j Repository自动生成功能。

package orders.config;

import org.neo4j.graphdb.GraphDatabaseService;
import org.neo4j.graphdb.factory.GraphDatabaseFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.neo4j.config.EnableNeo4jRepositories;
import org.springframework.data.neo4j.config.Neo4jConfiguration;

@Configuration
@EnableNeo4jRepositories(basePackages = "orders.db")
public class Neo4jConfig extends Neo4jConfiguration {

   public Neo4jConfig() {
      setBasePackage("orders");
   }

   @Bean(destroyMethod="shutdown")
   public GraphDatabaseService graphDatabaseService() {   
      return new GraphDatabaseFactory()
            .newEmbeddedDatabase("/tmp/graphdb");
   }
}

@EnableNeo4jRepositories注解能够让Spring Data Neo4j自动生成 Neo4j的Repository实现。定义GraphDatabaseService bean使用GraphDatabaseFactory 来创建嵌入式的Neo4j数据库。

Neo4j定义了两种类型的实体：节点和关联关系。节点反映了应用中的事物，而关联关系定义了这些事物是如何联系在一起的。

Order、Item是两个节点他们之间的关系是Order has items 

下面我们为Order添加注解，使其成为图数据库中的一个节点。

package orders;

import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Set;

import org.springframework.data.neo4j.annotation.GraphId;
import org.springframework.data.neo4j.annotation.NodeEntity;
import org.springframework.data.neo4j.annotation.RelatedTo;

@NodeEntity
public class Order {
   
   @GraphId
   private Long id;
   
   private String customer;
   
   private String type;
   
   @RelatedTo(type="HAS_ITEMS")
   private Set<Item> items = new LinkedHashSet<Item>();

   public String getCustomer() {
      return customer;
   }

   public void setCustomer(String customer) {
      this.customer = customer;
   }
   
   public String getType() {
      return type;
   }
   
   public void setType(String type) {
      this.type = type;
   }

   public Collection<Item> getItems() {
      return items;
   }

   public void setItems(Set<Item> items) {
      this.items = items;
   }

   public Long getId() {
      return id;
   }
   
}

@NodeEntity注解代表这是一个节点，@GraphId注解代表这是一个图Id，@RelatedTo(type="HAS_ITEMS")注解代表Order与一个Item的Set存在关系。

Item也是图数据库中的节点

package orders;

import org.springframework.data.neo4j.annotation.GraphId;
import org.springframework.data.neo4j.annotation.NodeEntity;

@NodeEntity
public class Item {
   
   @GraphId
   private Long id;
   
   private Order order;

   private String product;
   
   private double price;
   
   private int quantity;
   
   public Order getOrder() {
      return order;
   }

   public String getProduct() {
      return product;
   }

   public void setProduct(String product) {
      this.product = product;
   }

   public double getPrice() {
      return price;
   }

   public void setPrice(double price) {
      this.price = price;
   }

   public int getQuantity() {
      return quantity;
   }

   public void setQuantity(int quantity) {
      this.quantity = quantity;
   }

   public Long getId() {
      return id;
   }

}

同样我们需要创建自动化的Neo4j Repository

package orders.db;

import java.util.List;

import orders.Order;

import org.springframework.data.neo4j.repository.GraphRepository;

public interface OrderRepository extends GraphRepository<Order> {
   
   List<Order> findByCustomer(String customer);
   
   List<Order> findByCustomerLike(String customer);

   List<Order> findByCustomerAndType(String customer, String type);

   List<Order> getByType(String type);
      
// @Query("{customer:‘Chuck Wagon‘}")
// List<Order> findChucksOrders();

}

下面是测试类

package orders;

import static org.junit.Assert.*;

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

import orders.config.Neo4jConfig;
import orders.db.OrderRepository;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@ContextConfiguration(classes=Neo4jConfig.class)
@RunWith(SpringJUnit4ClassRunner.class)
public class Neo4jTest {

   @Autowired
   private OrderRepository orderRepository;

   @Before
   public void cleanup() {
      // Deleting all orders (just in case something is left over from a previous failed run)
      orderRepository.deleteAll();
   }
   
   @Test
   public void testNeo4jRepository() {
      assertEquals(0, orderRepository.count());
      Order order = createAnOrder();
      
      // Saving an order
      Order savedOrder = orderRepository.save(order);       
      assertEquals(1, orderRepository.count());
      
      // Finding an order by ID
      Order foundOrder = orderRepository.findOne(savedOrder.getId());
      assertEquals("Chuck Wagon", foundOrder.getCustomer());
      assertEquals(2, foundOrder.getItems().size());

      // Finding an order by a single field value
      List<Order> chucksOrders = orderRepository.findByCustomer("Chuck Wagon");
      assertEquals(1, chucksOrders.size());
      assertEquals("Chuck Wagon", chucksOrders.get(0).getCustomer());
      assertEquals(2, chucksOrders.get(0).getItems().size());

      // Finding an order by a single field value like
      List<Order> chuckLikeOrders = orderRepository.findByCustomerLike("Chuck.*");
      assertEquals(1, chuckLikeOrders.size());
      assertEquals("Chuck Wagon", chuckLikeOrders.get(0).getCustomer());
      assertEquals(2, chuckLikeOrders.get(0).getItems().size());

      // Finding an order by multiple field values
      List<Order> chucksWebOrders = orderRepository.findByCustomerAndType("Chuck Wagon", "WEB");
      assertEquals(1, chucksWebOrders.size());
      assertEquals("Chuck Wagon", chucksWebOrders.get(0).getCustomer());
      assertEquals(2, chucksWebOrders.get(0).getItems().size());

      List<Order> chucksPhoneOrders = orderRepository.findByCustomerAndType("Chuck Wagon", "PHONE");
      assertEquals(0, chucksPhoneOrders.size());

      // Finding an order by a custom query method
//    List<Order> chucksOrders2 = orderRepository.findChucksOrders();
//    assertEquals(1, chucksOrders2.size());
//    assertEquals("Chuck Wagon", chucksOrders2.get(0).getCustomer());
//    assertEquals(2, chucksOrders2.get(0).getItems().size());
      
      
      // Deleting an order
      orderRepository.delete(savedOrder.getId());
      assertEquals(0, orderRepository.count());     

   }

   private Order createAnOrder() {
      Order order = new Order();
      order.setCustomer("Chuck Wagon");
      order.setType("WEB");
      Item item1 = new Item();
      item1.setProduct("Spring in Action");
      item1.setQuantity(2);
      item1.setPrice(29.99);
      Item item2 = new Item();
      item2.setProduct("Module Java");
      item2.setQuantity(31);
      item2.setPrice(29.95);
      order.setItems(new HashSet<Item>(Arrays.asList(item1, item2)));
      return order;
   }
   
}

三、使用Redis操作键值对数据

Redis是一种特殊类型的数据库，它被称之为key-value存储，key-value存储与哈希Map有很大的相似性，可以把它理解为持久化的哈希Map。
连接Redis

package cart;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;

@Configuration
public class RedisConfig {

   @Bean
   public RedisConnectionFactory redisCF() {
      return new JedisConnectionFactory();
   }
   
   @Bean
   public RedisTemplate<String, Product> redisTemplate(RedisConnectionFactory cf) {
      RedisTemplate<String, Product> redis = new RedisTemplate<String, Product>();
      redis.setConnectionFactory(cf);
      return redis;
   }
   
}
我们配置RedisConnectionFactory bean 通过默认构造器创建的连接工厂会向localhost上的6379端口创建连接。顾名思义，Redis连接工厂会生成到Redis key-value存储的连接，我们使用RedisTemplate简化数据访问，能够让我们持久化各种类型的key和value。
将RedisConnectionFactory bean 注入到 RedisTemlate中，RedisTemplate使用两个类型进行参数化，第一个是key的类型，第二个是value的类型。

下面是Product类，实现了Serializable接口，因为Redis存储对象时需要将其序列化，取出时需要反序列化。

package cart;

import java.io.Serializable;

public class Product implements Serializable {

   private static final long serialVersionUID = 1L;
   
   private String sku;
   private String name;
   private float price;
   
   public String getSku() {
      return sku;
   }
   
   public void setSku(String sku) {
      this.sku = sku;
   }
   
   public String getName() {
      return name;
   }
   
   public void setName(String name) {
      this.name = name;
   }
   
   public float getPrice() {
      return price;
   }
   
   public void setPrice(float price) {
      this.price = price;
   }
   
}

下面是测试类的一部分

package cart;

import static org.junit.Assert.*;

import java.util.List;
import java.util.Set;

import org.junit.After;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.BoundListOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes=RedisConfig.class)
public class CartTest {

   /*
    * IMPORTANT: This test class requires that a Redis server be running on 
    *            localhost and listening on port 6379 (the default port).
    */
   
   @Autowired
   private RedisConnectionFactory cf;
   
   @Autowired
   private RedisTemplate<String, Product> redis;
   
   @After
   public void cleanUp() {
      redis.delete("9781617291203");
      redis.delete("cart");
      redis.delete("cart1");
      redis.delete("cart2");
   }
   
   @Test
   public void workingWithSimpleValues() {
      Product product = new Product();
      product.setSku("9781617291203");
      product.setName("Spring in Action");
      product.setPrice(39.99f);
      
      redis.opsForValue().set(product.getSku(), product);
      
      Product found = redis.opsForValue().get(product.getSku());
      assertEquals(product.getSku(), found.getSku());
      assertEquals(product.getName(), found.getName());
      assertEquals(product.getPrice(), found.getPrice(), 0.005);
   }
}