mongodb java 常用写法记录（备忘）

1. 数组 filter 的用法

Projections.computed("cnt", new BsonDocument("$size",
						new BsonDocument("$filter", new BsonDocument().append("input", new BsonString("$items"))
								.append("as", new BsonString("item")).append("cond", new BsonDocument("$eq",
										new BsonArray(Arrays.asList(new BsonString("$$item.status"), new BsonInt64(0))))