Java+MongoDB初探

1.准备工作

项目使用maven搭建，所以首要的工作需要加入mongodb的依赖，这里mongo-java-driver使用的是3.3.0的版本，bson依赖是mongoDB提供的BSON操作工具。

<dependency>
       <groupId>org.mongodb</groupId>
       <artifactId>bson</artifactId>
      <version>3.3.0</version>
</dependency>
<dependency>
       <groupId>org.mongodb</groupId>
       <artifactId>mongo-java-driver</artifactId>
       <version>3.3.0</version>
</dependency>

2.实例代码

代码之中包括了常见的操作：增删改查操作。

import com.mongodb.MongoClient;
import com.mongodb.MongoCredential;
import com.mongodb.ServerAddress;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;
import org.bson.Document;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import java.util.ArrayList;
import java.util.List;

/**
 * Created by veione on 2016/12/3.
 */
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:spring/applicationContext.xml")
public class MongoDBTest {
    private static final Logger logger = LoggerFactory.getLogger(MongoDBTest.class);

    @Test
    public void testConnectMongoDB() {
        // 连接到 mongodb 服务
        MongoClient mongoClient = new MongoClient("127.0.0.1", 27017);

        //连接到数据库
        MongoDatabase mongoDatabase = mongoClient.getDatabase("test");

        MongoCollection<Document> collection=mongoDatabase.getCollection("customers");

        FindIterable<Document> findIterable=collection.find(new Document("id",9527));
        MongoCursor<Document> mongoCursor=findIterable.iterator();
        while (mongoCursor.hasNext()){
            logger.info(mongoCursor.next().toJson());
        }
        mongoClient.close();
    }

    /**
     * 连接需要密码认证的方式
     */
    @Test
    public void testNeedAuthConnectDB() {
        ServerAddress serverAddress = new ServerAddress("127.0.0.1", 27017);
        List<ServerAddress> adds = new ArrayList<ServerAddress>();
        adds.add(serverAddress);

        MongoCredential credential = MongoCredential.createScramSha1Credential("username", "dbName", "password".toCharArray());

        List<MongoCredential> credentials = new ArrayList<MongoCredential>();
        credentials.add(credential);

        //通过连接认证获取MongoDB连接
        MongoClient mongoClient = new MongoClient(adds, credentials);

        //连接到数据库
        MongoDatabase mongoDatabase = mongoClient.getDatabase("test");
        System.out.println("connect to mongoDB successfully.");
        mongoClient.close();
    }

    @Test
    /**
     * 创建集合
     */
    public void testCreateCollection() {
        MongoClient mongoClient = new MongoClient("127.0.0.1", 27017);

        MongoDatabase mongoDatabase = mongoClient.getDatabase("test");

        mongoDatabase.createCollection("goods");

        System.out.println("create collection successfully.");
        mongoClient.close();
    }


    /**
     * 插入文档操作
     */
    @Test
    public void testInsertDocument() {
        // Connect to the mongoDB
        MongoClient mongoClient = new MongoClient("localhost", 27017);

        //连接到数据库
        MongoDatabase mongoDatabase = mongoClient.getDatabase("test");
        logger.info("connect to mongoDB successfully.");

        //选择集合对象
        MongoCollection<Document> collections = mongoDatabase.getCollection("customers");

        //插入文档
        Document doc = new Document("title", "MongoDB")
                .append("description", "Nosql Database")
                .append("lke", 100)
                .append("by", "peter");
        List<Document> docs = new ArrayList<Document>();
        docs.add(doc);

        collections.insertMany(docs);
        logger.info("insert document successfully.");
        mongoClient.close();
    }

    /**
     * 检索所有文档
     */
    @Test
    public void testSearchAllDocuments() {
        MongoClient mongoClient = new MongoClient("localhost", 27017);

        MongoDatabase mongoDatabase = mongoClient.getDatabase("test");

        MongoCollection<Document> collections = mongoDatabase.getCollection("customers");

        /**
         * 检索所有文档
         *
         * 1.获取迭代器FindIterable<Document>
         * 2.获取游标MongoCursor<Document>
         * 3.通过游标遍历检索出文档集合
         */
        FindIterable<Document> findIterable = collections.find();
        MongoCursor<Document> mongoCursor = findIterable.iterator();
        while (mongoCursor.hasNext()) {
            logger.info(mongoCursor.next().toJson());
        }
        mongoClient.close();
    }

    /**
     * 检索单个文档
     */
    @Test
    public void testSearchSingleDocument(){
        MongoClient mongoClient=new MongoClient("localhost",27017);

        MongoDatabase mongoDatabase=mongoClient.getDatabase("test");
        MongoCollection<Document> collections = mongoDatabase.getCollection("customers");


        FindIterable<Document> findIterable = collections.find(new Document("id",9527));
        MongoCursor<Document> mongoCursor = findIterable.iterator();
        while (mongoCursor.hasNext()) {
            logger.info(mongoCursor.next().toJson());
        }
        mongoClient.close();
    }

    /**
     * 更新文档
     */
    @Test
    public void testUpdateDocument(){
        MongoClient mongoClient=new MongoClient("localhost",27017);

        MongoDatabase mongoDatabase=mongoClient.getDatabase("test");

        MongoCollection<Document> collection=mongoDatabase.getCollection("customers");

        //更新文档,将文档中id=2的文档修改为id=9527
        collection.updateMany(Filters.eq("id",2),new Document("$set",new Document("id",9527)));

        //查看结果
        FindIterable<Document> findIterable=collection.find();
        MongoCursor<Document> mongoCursor=findIterable.iterator();
        while(mongoCursor.hasNext()){
            logger.info(mongoCursor.next().toJson());
        }
        mongoClient.close();
    }

    /**
     * 删除第一个文档
     */
    @Test
    public void testRemoveDocument(){
        MongoClient mongoClient=new MongoClient("localhost",27017);

        MongoDatabase mongoDatabase=mongoClient.getDatabase("test");

        MongoCollection<Document> collection=mongoDatabase.getCollection("customers");

        //删除符合条件的第一个文档
        collection.deleteOne(Filters.eq("like",2001));
        //删除所有符合条件的文档
        collection.deleteMany(Filters.eq("like",20001));
        //检索查看结果
        FindIterable<Document> findIterable=collection.find();
        MongoCursor<Document> mongoCursor=findIterable.iterator();

        while (mongoCursor.hasNext()){
            logger.info(mongoCursor.next().toJson());
        }
        mongoClient.close();
    }
}

3.总结

使用Java对MongoDB小试牛刀了一番，MongoDB基于BSON的格式使用起来非常方便，而且扩展性好，相对于关系型数据库先定义表后存放数据，MongoDB有更大的伸缩性，无须定义表的结构，存储数据直接创建集合插入数据到集合即可，简单高效。