MCP Server Demo

import mysql from 'mysql2/promise'; import { DatabaseConfig } from './database.js'; import { Pool as PgPool } from 'pg'; import sqlite3 from 'sqlite3'; export interface DatabaseConnection { connect(): Promise<void>; query(sql: string, params?: any[]): Promise<any>; close(): Promise<void>; getDatabases(): Promise<string[]>; switchDatabase(database: string): Promise<void>; } class MySQLConnection implements DatabaseConnection { private connection!: mysql.Connection; constructor(private config: DatabaseConfig) {} async connect(): Promise<void> { this.connection = await mysql.createConnection({ host: this.config.host, port: this.config.port, user: this.config.username, password: this.config.password, database: this.config.database, ...this.config.connectionOptions, }); } async query(sql: string, params?: any[]): Promise<any> { const [rows] = await this.connection.execute(sql, params); return rows; } async close(): Promise<void> { if (this.connection) { await this.connection.end(); } } async getDatabases(): Promise<string[]> { if (this.config.databases && this.config.databases.length > 0) { return this.config.databases; } const [rows] = await this.query('SHOW DATABASES'); return rows.map((row: any) => row.Database); } async switchDatabase(database: string): Promise<void> { await this.query(`USE \`${database}\``); } } class PostgreSQLConnection implements DatabaseConnection { private pool!: PgPool; constructor(private config: DatabaseConfig) {} async connect(): Promise<void> { this.pool = new PgPool({ host: this.config.host, port: this.config.port, user: this.config.username, password: this.config.password, database: this.config.database, ...this.config.connectionOptions, }); } async query(sql: string, params?: any[]): Promise<any> { const client = await this.pool.connect(); try { const result = await client.query(sql, params); return result.rows; } finally { // 释放连接 client.release(); } } async close(): Promise<void> { await this.pool.end(); } async getDatabases(): Promise<string[]> { if (this.config.databases && this.config.databases.length > 0) { return this.config.databases; } const result = await this.query('SELECT datname FROM pg_database WHERE datistemplate = false'); return result.map((row: any) => row.datname); } async switchDatabase(database: string): Promise<void> { await this.close(); this.config.database = database; await this.connect(); } } class SQLiteConnection implements DatabaseConnection { private db!: sqlite3.Database; constructor(private config: DatabaseConfig) {} async connect(): Promise<void> { return new Promise((resolve, reject) => { this.db = new sqlite3.Database(this.config.database, (err: any) => { if (err) reject(err); else resolve(); }); }); } async query(sql: string, params?: any[]): Promise<any> { return new Promise((resolve, reject) => { this.db.all(sql, params || [], (err, rows) => { if (err) reject(err); else resolve(rows); }); }); } async close(): Promise<void> { return new Promise((resolve, reject) => { this.db.close((err) => { if (err) reject(err); else resolve(); }); }); } async getDatabases(): Promise<string[]> { return this.config.databases || [this.config.database]; } async switchDatabase(database: string): Promise<void> { await this.close(); this.config.database = database; await this.connect(); } } export class ConnectionManager { private connections: Map<string, DatabaseConnection> = new Map(); async getConnection(config: DatabaseConfig): Promise<DatabaseConnection> { const key = config.id; if (!this.connections.has(key)) { let connection: DatabaseConnection; switch (config.type) { case 'mysql': connection = new MySQLConnection(config); break; case 'postgresql': connection = new PostgreSQLConnection(config); break; case 'sqlite': connection = new SQLiteConnection(config); break; default: throw new Error(`不支持的数据库类型: ${config.type}`); } await connection.connect(); this.connections.set(key, connection); } return this.connections.get(key)!; } async closeAll(): Promise<void> { for (const connection of this.connections.values()) { await connection.close(); } this.connections.clear(); } }