X DevAPI 用户指南  / 第 2 章连接和会话概念  /  2.3 使用会话对象

2.3 使用会话对象

之前的所有示例都使用了Session 对象的getSchema()或 getDefaultSchema()方法，它们返回一个 Schema 对象。您使用此 Schema 对象来访问 Collections 和 Tables。大多数示例利用 X DevAPI 的能力来链接所有对象构造，使您能够在一行中获得架构对象。例如： 

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schema = mysqlx.getSession(...).getSchema();

此对象链等同于以下内容，不同之处在于省略了中间步骤： 

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session = mysqlx.getSession(); 
schema = session.getSchema().

在您获得 Schema 对象之前，不需要始终进行链式调用，它也不总是您想要的。如果要使用 Session 对象，例如调用 Session 对象方法getSchemas()，则无需向下导航到 Schema。例如： 

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session = mysqlx.getSession(); session.getSchemas().

在此示例中，该mysqlx.getSession() 函数用于打开会话。然后该 Session.getSchemas()函数用于获取所有可用模式的列表并将它们打印到控制台。

MySQL 外壳 JavaScript 代码 

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// Connecting to MySQL and working with a Session
var mysqlx = require('mysqlx');

// Connect to a dedicated MySQL server using a connection URI
var mySession = mysqlx.getSession('user:password@localhost');

// Get a list of all available schemas
var schemaList = mySession.getSchemas();

print('Available schemas in this session:\n');

// Loop over all available schemas and print their name
for (index in schemaList) {
  print(schemaList[index].name + '\n');
}

mySession.close();

MySQL 外壳 Python 代码 

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# Connecting to MySQL and working with a Session
from mysqlsh import mysqlx

# Connect to a dedicated MySQL server using a connection URI
mySession = mysqlx.get_session('user:password@localhost')

# Get a list of all available schemas
schemaList = mySession.get_schemas()

print('Available schemas in this session:\n')

# Loop over all available schemas and print their name
for schema in schemaList:
        print('%s\n' % schema.name)

mySession.close()

Node.js JavaScript 代码 

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// Connecting to MySQL and working with a Session
var mysqlx = require('@mysql/xdevapi');

// Connect to a dedicated MySQL server using a connection URI
mysqlx
  .getSession('user:password@localhost')
  .then(function (mySession) {
    // Get a list of all available schemas
    return mySession.getSchemas();
  })
  .then(function (schemaList) {
    console.log('Available schemas in this session:\n');

    // Loop over all available schemas and print their name
    schemaList.forEach(function (schema) {
      console.log(schema.getName() + '\n');
    });
  });

C#代码 

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// Connect to a dedicated MySQL server node using a connection URI
var mySession = MySQLX.GetSession("mysqlx://user:password@localhost:33060");

// Get a list of all available schemas
var schemaList = mySession.GetSchemas();

Console.WriteLine("Available schemas in this session:");

// Loop over all available schemas and print their name
foreach (var schema in schemaList)
{
      Console.WriteLine(schema.Name);
}

mySession.Close();

Python代码 

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# Connector/Python
# Connecting to MySQL and working with a Session
from mysqlsh import mysqlx

# Connect to a dedicated MySQL server using a connection URI
mySession = mysqlx.get_session('user:password@localhost')

# Get a list of all available schemas
schemaList = mySession.get_schemas()

print('Available schemas in this session:\n')

# Loop over all available schemas and print their name
for schema in schemaList:
        print('%s\n' % schema.name)

mySession.close()

Java代码 

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import java.util.List;
import com.mysql.cj.xdevapi.*;

// Connecting to MySQL and working with a Session
// Connect to a dedicated MySQL server using a connection URI
Session mySession = new SessionFactory().getSession("mysqlx://localhost:33060/test?user=user&password=password");

// Get a list of all available schemas
List<Schema> schemaList = mySession.getSchemas();

System.out.println("Available schemas in this session:");

// Loop over all available schemas and print their name
for (Schema schema : schemaList) {
System.out.println(schema.getName());
}

mySession.close();

C++代码 

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#include <mysqlx/xdevapi.h>

// Connecting to MySQL and working with a Session

// Connect to a dedicated MySQL server using a connection URI
string url = "mysqlx://localhost:33060/test?user=user&password=password";
{
  Session mySession(url);

  // Get a list of all available schemas
  std::list<Schema> schemaList = mySession.getSchemas();

  cout << "Available schemas in this session:" << endl;

  // Loop over all available schemas and print their name
  for (Schema schema : schemaList) {
    cout << schema.getName() << endl;
  }
}