[英]Convert DBObject to a POJO using MongoDB Java Driver
MongoDB似乎返回了BSON / JSON對象。
我認為你肯定能夠以字符串,整數等方式檢索值,然后可以保存為POJO。
作為迭代列表的結果,我有一個DBObject(實例化為BasicDBObject)...(cur.next())。
除了使用某種持久性框架之外,唯一的方法是將數據放入POJO以使用JSON serlialiser / deserialiser嗎?
我的方法看起來像這樣:
public List<User> findByEmail(String email){
DBCollection userColl;
try {
userColl = Dao.getDB().getCollection("users"); } catch (UnknownHostException e) { e.printStackTrace(); } catch (MongoException e) { e.printStackTrace();}
DBCursor cur = userColl.find();
List<User> usersWithMatchEmail = new ArrayList<User>();
while(cur.hasNext()) {
// this is where I want to convert cur.next() into a <User> POJO
usersWithMatchEmail.add(cur.next());
}
return null;
}
編輯:很明顯,只是做這樣的事情。
讓Spring用它已經為此建造的東西做繁重的工作......
真正的訣竅是:mongoTemplate.getConverter()。read(Foo.class,obj);
例如,使用DBCursor時 -
while (cursor.hasNext()) {
DBObject obj = cursor.next();
Foo foo = mongoTemplate.getConverter().read(Foo.class, obj);
returnList.add(foo);
}
http://revelfire.com/spring-data-mongodb-convert-from-raw-query-dbobject/
有一些java庫可以幫助你:
雖然回答很晚,但有人可能覺得這很有用。
我使用GSON從BasicDBObject
轉換為我自己的POJO,即TinyBlogDBObject
TinyBlogDBObject obj = convertJSONToPojo(cursor.next().toString());
private static TinyBlogDBObject convertJSONToPojo(String json){
Type type = new TypeToken< TinyBlogDBObject >(){}.getType();
return new Gson().fromJson(json, type);
}
1.為MongoDatabase bean提供適當的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.注釋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.查詢mongoDB並獲取POJOS
MongoCollection<Document> collection = mongoDatabase.getCollection("product");
Document query = new Document();
List<ProductEntity> products = collection.find(query, ProductEntity.class).into(new ArrayList<>());
請在其他帖子中查看我的答案
POJO to org.bson.Document and Vice Versa
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