POJO to org.bson.Document and Vice Versa

Question

有没有简单的方法将Simple POJO转换为org.bson.Document？

我知道有很多方法可以像这样做:

Document doc = new Document();
doc.append("name", person.getName()):

但它有一个更简单和更错误的方式吗？

Answer 1

目前Mongo Java Driver 3.9.1提供了开箱即用的POJO支持
http://mongodb.github.io/mongo-java-driver/3.9/driver/getting-started/quick-start-pojo/
假设你有这样的例子使用一个嵌套对象的集合

db.createCollection("product", {
validator: {
    $jsonSchema: {
        bsonType: "object",
        required: ["name", "description", "thumb"],
        properties: {
            name: {
                bsonType: "string",
                description: "product - name - string"
            },
            description: {
                bsonType: "string",
                description: "product - description - string"
            },
            thumb: {
                bsonType: "object",
                required: ["width", "height", "url"],
                properties: {
                    width: {
                        bsonType: "int",
                        description: "product - thumb - width"
                    },
                    height: {
                        bsonType: "int",
                        description: "product - thumb - height"
                    },
                    url: {
                        bsonType: "string",
                        description: "product - thumb - url"
                    }
                }
            }

        }
    }
}});

1.为MongoDatabase bean提供适当的CodecRegistry

@Bean
public MongoClient mongoClient() {
    ConnectionString connectionString = new ConnectionString("mongodb://username:password@127.0.0.1:27017/dbname");

    ConnectionPoolSettings connectionPoolSettings = ConnectionPoolSettings.builder()
            .minSize(2)
            .maxSize(20)
            .maxWaitQueueSize(100)
            .maxConnectionIdleTime(60, TimeUnit.SECONDS)
            .maxConnectionLifeTime(300, TimeUnit.SECONDS)
            .build();

    SocketSettings socketSettings = SocketSettings.builder()
            .connectTimeout(5, TimeUnit.SECONDS)
            .readTimeout(5, TimeUnit.SECONDS)
            .build();

    MongoClientSettings clientSettings = MongoClientSettings.builder()
            .applyConnectionString(connectionString)
            .applyToConnectionPoolSettings(builder -> builder.applySettings(connectionPoolSettings))
            .applyToSocketSettings(builder -> builder.applySettings(socketSettings))
            .build();

    return MongoClients.create(clientSettings);
}

@Bean 
public MongoDatabase mongoDatabase(MongoClient mongoClient) {
    CodecRegistry defaultCodecRegistry = MongoClientSettings.getDefaultCodecRegistry();
    CodecRegistry fromProvider = CodecRegistries.fromProviders(PojoCodecProvider.builder().automatic(true).build());
    CodecRegistry pojoCodecRegistry = CodecRegistries.fromRegistries(defaultCodecRegistry, fromProvider);
    return mongoClient.getDatabase("dbname").withCodecRegistry(pojoCodecRegistry);
}

2.注释您的POJOS

public class ProductEntity {

    @BsonProperty("name") public final String name;
    @BsonProperty("description") public final String description;
    @BsonProperty("thumb") public final ThumbEntity thumbEntity;

    @BsonCreator
    public ProductEntity(
            @BsonProperty("name") String name,
            @BsonProperty("description") String description,
            @BsonProperty("thumb") ThumbEntity thumbEntity) {
        this.name = name;
        this.description = description;
        this.thumbEntity = thumbEntity;
    }
}

public class ThumbEntity {

    @BsonProperty("width") public final Integer width;
    @BsonProperty("height") public final Integer height;
    @BsonProperty("url") public final String url;

    @BsonCreator
    public ThumbEntity(
            @BsonProperty("width") Integer width,
            @BsonProperty("height") Integer height,
            @BsonProperty("url") String url) {
        this.width = width;
        this.height = height;
        this.url = url;
    }
}

3.查询mongoDB并获取POJOS

MongoCollection<Document> collection = mongoDatabase.getCollection("product");
Document query = new Document();
List<ProductEntity> products = collection.find(query, ProductEntity.class).into(new ArrayList<>());

就是这样!!! 您可以轻松获取POJOS而无需繁琐的手动映射,也不会失去运行本机mongo查询的能力

Answer 2

您可以使用Gson和Document.parse(String json)将POJO转换为Document.这适用于java驱动程序的3.4.2版.

像这样的东西:

package com.jacobcs;

import org.bson.Document;

import com.google.gson.Gson;
import com.mongodb.MongoClient;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class MongoLabs {

    public static void main(String[] args) {
        // create client and connect to db
        MongoClient mongoClient = new MongoClient("localhost", 27017);
        MongoDatabase database = mongoClient.getDatabase("my_db_name");

        // populate pojo
        MyPOJO myPOJO = new MyPOJO();
        myPOJO.setName("MyName");
        myPOJO.setAge("26");

        // convert pojo to json using Gson and parse using Document.parse()
        Gson gson = new Gson();
        MongoCollection<Document> collection = database.getCollection("my_collection_name");
        Document document = Document.parse(gson.toJson(myPOJO));
        collection.insertOne(document);
    }

}

Answer 3

我不知道你的 MongoDB 版本。但现在，没有必要将 Document 转换为 POJO，反之亦然。您只需要根据您想要使用的内容（文档或 POJO）创建集合，如下所示。

//If you want to use Document
MongoCollection<Document> myCollection = db.getCollection("mongoCollection");
Document doc=new Document();
doc.put("name","ABC");
myCollection.insertOne(doc);


//If you want to use POJO
MongoCollection<Pojo> myCollection = db.getCollection("mongoCollection",Pojo.class);
Pojo obj= new Pojo();
obj.setName("ABC");
myCollection.insertOne(obj);

如果您想使用 POJO，请确保您的 Mongo DB 配置了正确的 codecregistry。

MongoClient mongoClient = new MongoClient();
//This registry is required for your Mongo document to POJO conversion
CodecRegistry codecRegistry = fromRegistries(MongoClient.getDefaultCodecRegistry(),
        fromProviders(PojoCodecProvider.builder().automatic(true).build()));
MongoDatabase db = mongoClient.getDatabase("mydb").withCodecRegistry(codecRegistry);

Answer 4

关键是，您不需要把手放在 org.bson.Document 上。

Morphia 会在幕后为您做这一切。

import com.mongodb.MongoClient;
import org.mongodb.morphia.Datastore;
import org.mongodb.morphia.DatastoreImpl;
import org.mongodb.morphia.Morphia;
import java.net.UnknownHostException;

.....
    private Datastore createDataStore() throws UnknownHostException {
        MongoClient client = new MongoClient("localhost", 27017);
        // create morphia and map classes
        Morphia morphia = new Morphia();
        morphia.map(FooBar.class);
        return new DatastoreImpl(morphia, client, "testmongo");
    }

......

    //with the Datastore from above you can save any mapped class to mongo
    Datastore datastore;
    final FooBar fb = new FooBar("hello", "world");
    datastore.save(fb);

在这里您会找到几个示例： https: //mongodb.github.io/morphia/