MongoDB支持C、C++、C#、GO、Java、NodeJS、PHP、Python、Ruby、Rust、Scala和Swift语言的驱动程序，MongoDB 提供了当前所有主流开发语言的数据库驱动包，开发人员使用以上任何一种主流开发语言都可以轻松编程，实现访问MongoDB 数据库。[^3]
现在只介绍Java语言通过MongoDB驱动程序对MongoDB数据库的基本操作，mongodb-dirver-sync是MongoDB官方推出的驱动程序，这里使用的版本为4.6.1，MongoDB版本为v5.0.2，jdk版本为jdk1.8具体的数据库和驱动版本的兼容性关系参照MongoDB Compatibility。
引入maven依赖
在项目中引入如下依赖，具体版本根据需要连接的MongoDB数据库自行确定，这里是4.6.1
<dependency>
<groupId>org.mongodb</groupId>
<artifactId>mongodb-driver-sync</artifactId>
<version>4.6.1</version>
</dependency>
编辑配置文件
配置文件的作用是用来保存MongoDB的连接信息，如ip，端口号等，在实际开发过程中对这种配置信息尽量使用配置文件，减少硬编码。配置文件内容如下：
# 配置文件保存路径为：resource/config/mongodb.properties
mongodb.uri.host=127.0.0.1
mongodb.uri.port=27017
mongodb.uri.database=MongoStudy
mongodb.database.defaultCollection=game
建立连接后进行相关操作
通过代码读取配置信息，建立MongoDB连接并进行相关操作，具体代码如下：
package top.sunyog.mongo;
import com.mongodb.client.*;
import com.mongodb.client.model.Filters;
import org.bson.Document;
import org.bson.conversions.Bson;
import java.io.*;
import java.net.URL;
import java.text.MessageFormat;
import java.util.Properties;
public class MongoDemoApp {
public static void main(String[] args) {
//读取properties配置文件
Properties properties = new Properties();
URL uri = MongoDemoApp.class.getClassLoader().getResource("config/mongodb.properties");
try (InputStream in = new FileInputStream(uri.getFile());
BufferedInputStream bin = new BufferedInputStream(in)) {
properties.load(bin);
String host = properties.getProperty("mongodb.uri.host");
String port = properties.getProperty("mongodb.uri.port");
String db = properties.getProperty("mongodb.uri.database");
String defaultColl = properties.getProperty("mongodb.database.defaultCollection");
//构建数据库url
final String urlFormatter="mongodb://{0}:{1}";
String conn = MessageFormat.format(urlFormatter, host, port);
//建立连接
MongoClient client = MongoClients.create(conn);
//进行数据库相关操作
//...
} catch (FileNotFoundException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
和MongoDB shell一样，使用Java向MongoDB插入数据也有两种方法，insertOne()和insertMany()，两个函数的区别在于入参，一个是Document对象，一个是List<Document>对象。主要用法如下：
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.InsertOneResult;
import org.bson.Document;
import org.bson.conversions.Bson;
import java.util.Arrays;
public class InsertDemo {
private void insertDocument(MongoCollection coll) {
Document doc = new Document();
doc.append("name", "terraria").append("price", 18);
doc.put("platform", Arrays.asList("PSX","XBOX","steam","switch"));
InsertOneResult insertRes = coll.insertOne(doc);
}
}
通过以下查询插入的数据：
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.InsertOneResult;
import org.bson.Document;
import org.bson.conversions.Bson;
import java.util.Arrays;
public class InsertDemo {
private void findById(MongoCollection coll,InsertOneResult insertRes){
Bson filter = Filters.eq("_id", insertRes.getInsertedId());
MongoCursor cursor = coll.find(filter).iterator();
while (cursor.hasNext()){
System.out.println(cursor.next());
}
}
}
控制台打印结果如下：
Document{{_id=62c53f733ae2f874816f4a85, name=terraria, price=18, platform=[PSX, XBOX, steam, switch]}}
批量插入数据代码样例：
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.InsertManyResult;
import com.mongodb.client.result.InsertOneResult;
import org.bson.BsonValue;
import org.bson.Document;
import org.bson.conversions.Bson;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
public class InsertDemo {
private void insertDocuments(MongoCollection coll) {
//生成数据
List<Document> documents = Arrays.asList(
new Document().append("name", "overcooked! 2").append("price", 24),
new Document().append("name","titan fall 2").append("price",25)
);
//插入数据
InsertManyResult insertManyResult = coll.insertMany(documents);
//查询数据
for (Map.Entry<Integer, BsonValue> entry : insertManyResult.getInsertedIds().entrySet()) {
BsonValue idVal = entry.getValue();
coll.find(Filters.eq("_id",idVal)).forEach(o->{
System.out.println(o);
});
}
}
}
执行程序，打印出的数据结果如下：
Document{{_id=62c6395b615f8a447cb82710, name=overcooked! 2, price=24}}
Document{{_id=62c6395b615f8a447cb82711, name=titan fall 2, price=25}}
带选项的批量插入:
List<Document> documents = Arrays.asList(
new Document().append("name", "overcooked! 2").append("price", 24),
new Document().append("name", "pummel party").append("price", 30),
new Document().append("name", "cup head").append("price", 47),
new Document().append("name", "ori").append("price", 29)
);
InsertManyOptions options = new InsertManyOptions().ordered(false);
InsertManyResult res = coll.insertMany(documents, options);
deleteOne()方法代码样例:
package top.sunyog.mongo.delete;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.DeleteResult;
public class DeleteDemo {
private void deleteDocument(MongoCollection coll) {
DeleteResult res = coll.deleteOne(Filters.eq("name", "titan fall 2"));
System.out.println(res);
}
}
执行结果:
AcknowledgedDeleteResult{deletedCount=1}
deleteMany()方法代码样例:
package top.sunyog.mongo.delete;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.DeleteResult;
public class DeleteDemo {
private void deleteManyDocuments(MongoCollection coll) {
Bson filter_1 = Filters.eq("name", "overcooked! 2");
Bson filter_2 = Filters.eq("name", "terraria");
Bson filter = Filters.or(filter_1, filter_2);
DeleteResult res = coll.deleteMany(filter);
long count = res.getDeletedCount();
System.out.println("delete many function result: count="+count);
}
}
执行结果:
delete many function result: count=2
replaceOne()方法用于对文档进行替换, 实例代码如下:
package top.sunyog.mongo.update;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.model.Filters;
import com.mongodb.client.result.UpdateResult;
import org.bson.Document;
import java.util.Arrays;
public class UpdateDemo {
private void replaceOneDoc(MongoCollection<Document> coll) {
Document doc = new Document().append("name", "ori").append("price", 129)
.append("platform", Arrays.asList("switch", "steam"));
UpdateResult res = coll.replaceOne(Filters.eq("name", "ori"), doc);
System.out.println(res);
}
}
测试更新结果:
> db.game.find({"name":"ori"}).pretty()
{
"_id" : ObjectId("62c64528eb52555d87933438"),
"name" : "ori",
"price" : 129,
"platform" : [
"switch",
"steam"
]
}