MongoDB常用Java Api

1.连接到单个mongodb实例

(1)连接到端口上localhost上运行的MongoDB实例

MongoClient mongoClient = MongoClients.create();

(2)指定主机名以连接到端口上指定主机上运行的MongoDB实例

MongoClient mongoClient = MongoClients.create(
MongoClientSettings.builder()
.applyToClusterSettings(builder -> builder.hosts(Arrays.asList(new ServerAddress("hostOne")))).build());

(3)指定主机名和端口

MongoClient mongoClient = MongoClients.create(
MongoClientSettings.builder()
.applyToClusterSettings(builder -> builder.hosts(Arrays.asList(new ServerAddress("hostOne", 27018)))).build());

(4)指定ConnectionString

MongoClient mongClient = MongClients.create("mongodb://hostOne:27017,hostTwo:27018");

3.获取数据库对象

MongoDatabase database = mongoClient.getDatabase(dataBaseName);

4.获取集合对象

MongoCollection<Document> collection = database.getCollection(collectionName);

5.创建文档对象
{
"name" : "MongoDB",
"type" : "database",
"count" : 1,
"versions": [ "v3.2", "v3.0", "v2.6" ],
"info" : { x : 203, y : 102 }
}

Document document = new Document("name", "MongoDB")
.append("type", "database")
.append("count", 1)
.append("versions", Arrays.asList("v3,2", "v3.0", "v2.6"))
.append("info", new Document("x", 203).append("y", 102));

collection.insertOne(document);--插入单个文档对象

collection.insertMany(documents);--插入多个文档对象

6.计算集合中的文档数

collection.countDocuments();

7.查询文档对象

(1)查询一个或者第一个文档对象

Document doc = collection.find().first();

(2)查询所有文档对象

MongoCursor<Document> cursor = collection.find().iterator();
try {
while (cursor.hasNext()) {
System.out.println(cursor.next().toJson());
}
} finally {
cursor.close();
}

(3)通过过滤器(Filters)查询文档对象

collection.find(eq("name", "张三"));
Block<Document> printBlock = new Block<Document>() {
@Override
public void apply(final Document document) {
System.out.println(document.toJson());
}
};
collection.find(gt("age", 12)).forEach(printBlock);
collection.find(and(gt("age", 12), lte("age", 30))).forEach(printBlock);

8.更新文档对象

collection.updateOne(eq("age", 10), new Document("$set", new Document("age", 100)));--更新单个文档对象

UpdateResult updateResult = collection.updateMany(gt("age", 10), inc("age", 1));--更新多个文档对象

9.删除文档对象

collection.deleteOne(gte("age", 10)).--删除单个文档对象

DeleteResult deleteResult = collection.deleteMany(gte("age", 10));--删除多个文档对象

10.其他查询
(1) 根据sex分组，获取age最大值

Document groupDocument = new Document();
groupDocument.put("_id", "$sex");
groupDocument.put("max_age",new Document("$max","$age"));
Document group = new Document("$group",groupDocument);
documents.add(group);
MongoCursor<Document> cursor = collection.aggregate(documents).iterator();

(2) 根据sex分组，根据age求和

Document groupDocument = new Document();
groupDocument.put("_id", "$sex");
groupDocument.put("sum_age",new Document("$sum","$age"));
Document group = new Document("$group",groupDocument);
documents.add(group);
MongoCursor<Document> cursor = collection.aggregate(documents).iterator();

(3) 查询sex 为FeMale按age降序，并取第11-20条数据

MongoCursor<Document> cursor = collection.find(new Document("sex", "FeMale"))
.sort(new Document("age", -1)).skip(10).limit(10).iterator();

(4) 去除sex字段的重复值

MongoCursor<String> cursor = collection.distinct("sex", String.class).iterator();