<dependency> 
 <groupId>org.mongodb</groupId> 
 <artifactId>mongodb-driver</artifactId> 
 <version>3.10.1</version> 
</dependency>

@Test 
public void test1() { 
 //创建连接 
 MongoClient client = new MongoClient("192.168.200.128");
 //打开数据库 
 MongoDatabase commentdb = client.getDatabase("commentdb"); 
 //获取集合 
 MongoCollection<Document> comment = commentdb.getCollection("comment"); 
 //查询 
 FindIterable<Document> documents = comment.find(); 
 //查询记录获取文档集合 
 for (Document document : documents) { 
 System.out.println("_id：" + document.get("_id")); 
 System.out.println("内容：" + document.get("content")); 
 System.out.println("用户ID:" + document.get("userid")); 
 System.out.println("点赞数：" + document.get("thumbup")); }
 //关闭连接 
 client.close(); 
 }
 } 

private MongoClient client; 
private MongoCollection<Document> comment; 
@Before 
public void init() { 
 //创建连接 
 client = new MongoClient("192.168.200.128"); 
 //打开数据库 
 MongoDatabase commentdb = client.getDatabase("commentdb"); 
 //获取集合 
 comment = commentdb.getCollection("comment"); 
}
@After 
public void after() { 
 client.close(); 
}
@Test public void test2() { 
 //查询 
 FindIterable<Document> documents = comment.find(new BasicDBObject("_id", "1")); 
 //查询记录获取文档集合 
 for (Document document : documents) { 
 System.out.println("_id：" + document.get("_id")); 
 System.out.println("内容：" + document.get("content")); 
 System.out.println("用户ID:" + document.get("userid")); 
 System.out.println("点赞数：" + document.get("thumbup")); 
 } 
}

@Test public void test3() { 
 Map<String, Object> map = new HashMap(); 
 map.put("_id", "6"); 
 map.put("content", "很棒！"); 
 map.put("userid", "9999"); 
 map.put("thumbup", 123); 
 Document document = new Document(map); 
 comment.insertOne(document); 
}

@Test public void test4() { 
 //修改的条件 
 Bson filter = new BasicDBObject("_id", "6"); 
 //修改的数据 
 Bson update = new BasicDBObject("$set", new Document("userid", "8888"));
 comment.updateOne(filter, update); 
}

@Test public void test5() { 
 //删除的条件 
 Bson filter = new BasicDBObject("_id", "6"); 
 comment.deleteOne(filter); 
}