Connection Guide连接指南

Connection URI连接URI

The connection URI is the set of instructions that the driver uses to connect to a MongoDB deployment. 连接URI是驱动程序用来连接到MongoDB部署的一组指令。It instructs the driver on how it should connect to MongoDB and how it should behave while connected. 它指导驱动程序如何连接到MongoDB，以及连接时的行为。The following example shows each part of the connection URI:以下示例显示了连接URI的每个部分：

In this example, we use mongodb for the protocol, which specifies the Standard Connection String Format.在本例中，我们使用mongodb作为协议，它指定了标准连接字符串格式。

If your instance or deployment has a DNS SRV record, you can use the DNS Seed List Connection Format for your connection string. 如果您的实例或部署具有DNS SRV记录，则可以对连接字符串使用DNS种子列表连接格式。This format offers more flexibility of deployment and the ability to change the servers in rotation without reconfiguring clients.这种格式提供了更大的部署灵活性，并且能够在不重新配置客户端的情况下轮流更改服务器。

The next part of the connection string contains your credentials if you are using password-based authentication. 如果您使用基于密码的身份验证，则连接字符串的下一部分包含您的凭据。Replace the value of user with your username and pass with your password. 将user的值替换为您的用户名，并使用您的pass进行传递。If you are using an authentication mechanism that does not require a username and password, omit this part of the connection URI.如果您使用的身份验证机制不需要用户名和密码，请省略连接URI的这一部分。

The next part of the connection string specifies the hostname or IP address of your MongoDB instance, followed by the port number. 连接字符串的下一部分指定MongoDB实例的主机名或IP地址，后跟端口号。In the example above, we use sample.host as the hostname and 27017 as the port. 在上面的示例中，我们使用sample.host作为主机名，27017作为端口。Replace these values to point to your MongoDB instance.将这些值替换为指向您的MongoDB实例。

The last part of the connection string contains connection and authentication options as parameters. 连接字符串的最后一部分包含作为参数的连接和身份验证选项。In the example above, we set two connection options: maxPoolSize=20 and w=majority. 在上面的例子中，我们设置了两个连接选项：maxPoolSize=20和w=majority。For more information on connection options, skip to the Connection Options section.有关连接选项的详细信息，请跳到连接选项部分。

Atlas Connection ExampleAtlas连接示例

You must create a client to connect to a MongoDB deployment on Atlas. 您必须创建一个客户端才能连接到Atlas上的MongoDB部署。To create a client, construct an instance of MongoClient, passing in your URI and a MongoClientOptions object.要创建客户端，请构造MongoClient的实例，传入URI和MongoClientOptions对象。

Use the serverApi option in your MongoClientOptions object to enable the Stable API feature, which forces the server to run operations with behavior compatible with the specified API version.使用MongoClientOptions对象中的serverApi选项启用Stable API功能，该功能强一致性务器运行行为与指定API版本兼容的操作。

The following code shows how you can specify the connection string and the Stable API client option when connecting to a MongoDB deployment on Atlas and verify that the connection is successful:以下代码显示了如何在连接到Atlas上的MongoDB部署时指定连接字符串和Stable API客户端选项，并验证连接是否成功：

const { MongoClient, ServerApiVersion } = require("mongodb");

// Replace the placeholder with your Atlas connection string将占位符替换为Atlas连接字符串
const uri = "<connection string>";

// Create a MongoClient with a MongoClientOptions object to set the Stable API version创建一个带有MongoClientOptions对象的MongoClient来设置Stable API版本
const client = new MongoClient(uri,  {
        serverApi: {
            version: ServerApiVersion.v1,
            strict: true,
            deprecationErrors: true,
        }
    }
);

async function run() {
  try {
    // Connect the client to the server (optional starting in v4.7)将客户端连接到服务器（可选，从v4.7开始）
    await client.connect();

    // Send a ping to confirm a successful connection发送ping以确认连接成功
    await client.db("admin").command({ ping: 1 });
    console.log("Pinged your deployment. You successfully connected to MongoDB!");
  } finally {
    // Ensures that the client will close when you finish/error确保客户端在您完成/出错时关闭
    await client.close();
  }
}
run().catch(console.dir);

To learn more about the Stable API feature, see the Stable API page.要了解有关Stable API功能的更多信息，请参阅Stable API页面。

Other Ways to Connect to MongoDB连接MongoDB的其他方法

If you are connecting to a single MongoDB server instance or replica set that is not hosted on Atlas, see the following sections to find out how to connect.如果您要连接到一个未托管在Atlas上的MongoDB服务器实例或副本集，请参阅以下部分了解如何连接。

mongodb://localhost:<port>

mongodb://host1:27017,host2:27017,host3:27017/?replicaSet=myRs