feat: migrate configuration to .env environment variables

This commit implements a complete migration from JSON-based configuration
to .env environment variables, providing better security and flexibility.

Key Changes:
- Add python-dotenv dependency for environment variable support
- Create config/env_loader.py with type conversion utilities
- Add from_env() class methods to all config dataclasses
- Update ConfigLoader to prioritize environment variables
- Add save_to_env() method for .env file management
- Implement database connection factory pattern
- Add base DAO and connection classes for better abstraction
- Support both SQL Server and MySQL with unified interface
- Create migration script (scripts/migrate_to_env.py)
- Update GUI to read/write .env files
- Add comprehensive migration documentation

New Files:
- config/env_loader.py - Environment variable loader
- db/base_connection.py - Base database connection interface
- db/base_dao.py - Base DAO with common utilities
- db/connection_factory.py - Factory for creating connections
- db/mysql_connection.py - MySQL-specific connection
- db/sqlserver_connection.py - SQL Server-specific connection
- db/table_name_converter.py - SQL dialect converter
- scripts/migrate_to_env.py - Configuration migration tool
- docs/ENV_MIGRATION.md - Complete migration guide
- .env.example - Environment variable template

Testing:
- Verified MySQL connection (8.0.44)
- Tested all DAO operations
- Confirmed 150 tables accessible
- Validated configuration loading

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

config/loader.py

@@ -3,29 +3,51 @@
 """
 配置加载器
 
-负责加载、合并和验证配置。
+负责加载、合并和验证配置，优先从环境变量加载。
 """
 import json
 import os
 from typing import Any, Dict
-from config.schema import AppConfig
+from config.schema import (
+    AppConfig,
+    ERPConfig,
+    DatabaseConfig,
+    PathConfig,
+    ExtractionConfig,
+    ValidationConfig,
+    DatabaseType,
+    SQLServerConfig,
+    MySQLConfig,
+)
 from config.defaults import DEFAULT_APP_CONFIG, DEFAULT_SETTINGS_DICT
+from config.env_loader import get_env, get_env_bool, get_env_int
 
 
 class ConfigLoader:
     """配置加载器"""
 
     @staticmethod
-    def load(config_file: str = "config/user_settings.json") -> AppConfig:
+    def load(config_file: str = "config/user_settings.json", use_env: bool = True) -> AppConfig:
         """
-        加载配置文件
+        加载配置
+
+        优先级：
+        1. 环境变量（如果 use_env=True）
+        2. JSON 配置文件（如果存在）
+        3. 默认配置
 
         Args:
             config_file: 配置文件路径
+            use_env: 是否使用环境变量，默认为 True
 
         Returns:
             应用配置对象
         """
+        # 优先从环境变量加载
+        if use_env:
+            return AppConfig.from_env()
+
+        # 如果不使用环境变量，则从 JSON 文件加载（向后兼容）
         if os.path.exists(config_file):
             try:
                 with open(config_file, "r", encoding="utf-8") as f:
@@ -66,6 +88,63 @@ class ConfigLoader:
             print(f"保存配置文件失败: {e}")
             return False
 
+    @staticmethod
+    def save_to_env(config: AppConfig, env_file: str = ".env") -> bool:
+        """
+        保存配置到 .env 文件
+
+        Args:
+            config: 应用配置对象
+            env_file: .env 文件路径
+
+        Returns:
+            保存是否成功
+        """
+        from config.env_loader import save_env_file
+
+        env_dict = {
+            # ERP 配置
+            "ERP_URL": config.erp.url,
+            "ERP_USERNAME": config.erp.username,
+            "ERP_PASSWORD": config.erp.password,
+            "ERP_HEADLESS": config.erp.headless,
+            "ERP_IGNORE_HTTPS_ERRORS": config.erp.ignore_https_errors,
+            "ERP_AUTO_CLOSE_BROWSER": config.erp.auto_close_browser,
+            # 数据库配置
+            "DB_TYPE": config.database.db_type.value,
+            "DB_SERVER": config.database.server,
+            "DB_NAME": config.database.database,
+            "DB_USERNAME": config.database.username,
+            "DB_PASSWORD": config.database.password,
+            # SQL Server 特定配置
+            "DB_SQLSERVER_DRIVER": config.database.sqlserver.driver if config.database.sqlserver else "ODBC Driver 18 for SQL Server",
+            "DB_TRUST_SERVER_CERTIFICATE": config.database.sqlserver.trust_server_certificate if config.database.sqlserver else "yes",
+            # MySQL 特定配置
+            "DB_MYSQL_HOST": config.database.mysql.host if config.database.mysql else "",
+            "DB_MYSQL_PORT": config.database.mysql.port if config.database.mysql else 3306,
+            "DB_MYSQL_CHARSET": config.database.mysql.charset if config.database.mysql else "utf8mb4",
+            # 路径配置
+            "PATH_DATA_DIR": config.paths.data_dir,
+            "PATH_PRODUCTION_ID_FILE": config.paths.production_id_file,
+            "PATH_DEFAULT_OUTPUT": config.paths.default_output,
+            "PATH_VALIDATION_OUTPUT": config.paths.validation_output,
+            # 数据提取配置
+            "EXTRACTION_BATCH_SIZE": config.extraction.batch_size,
+            "EXTRACTION_VERBOSE": config.extraction.verbose,
+            "EXTRACTION_AUTO_CONVERT": config.extraction.auto_convert,
+            "EXTRACTION_MERGE_BATCHES": config.extraction.merge_batches,
+            "EXTRACTION_ENABLE_DB_PERSISTENCE": config.extraction.enable_db_persistence,
+            # 校验配置
+            "VALIDATION_DATA_SOURCE": config.validation.data_source,
+            "VALIDATION_USE_DATABASE": config.validation.use_database,
+            "VALIDATION_BATCH_SIZE": config.validation.batch_size,
+            "VALIDATION_ENABLE_CRUD": config.validation.enable_crud_operations,
+            "VALIDATION_DEFAULT_MANAGER": config.validation.default_manager,
+            "VALIDATION_MATCH_MODE": config.validation.match_mode,
+        }
+
+        return save_env_file(env_file, env_dict)
+
     @staticmethod
     def _merge_settings(defaults: Dict, loaded: Dict) -> Dict:
         """
@@ -109,6 +188,28 @@ class ConfigLoader:
         extraction_dict = settings.get("extraction", {})
         validation_dict = settings.get("validation", {})
 
+        # 解析数据库类型
+        db_type_str = database_dict.get("db_type", "sqlserver")
+        try:
+            db_type = DatabaseType(db_type_str)
+        except ValueError:
+            db_type = DatabaseType.SQLSERVER
+
+        # 解析 SQL Server 配置
+        sqlserver_dict = database_dict.get("sqlserver", {})
+        sqlserver_config = SQLServerConfig(
+            driver=sqlserver_dict.get("driver", "ODBC Driver 18 for SQL Server"),
+            trust_server_certificate=sqlserver_dict.get("trust_server_certificate", "yes"),
+        )
+
+        # 解析 MySQL 配置
+        mysql_dict = database_dict.get("mysql", {})
+        mysql_config = MySQLConfig(
+            host=mysql_dict.get("host", database_dict.get("server", "")),
+            port=mysql_dict.get("port", 3306),
+            charset=mysql_dict.get("charset", "utf8mb4"),
+        )
+
         return AppConfig(
             erp=ERPConfig(
                 url=erp_dict.get("url", ""),
@@ -119,14 +220,13 @@ class ConfigLoader:
                 auto_close_browser=erp_dict.get("auto_close_browser", True),
             ),
             database=DatabaseConfig(
+                db_type=db_type,
                 server=database_dict.get("server", ""),
                 database=database_dict.get("database", ""),
                 username=database_dict.get("username", ""),
                 password=database_dict.get("password", ""),
-                driver=database_dict.get("driver", "ODBC Driver 18 for SQL Server"),
-                trust_server_certificate=database_dict.get(
-                    "trust_server_certificate", "yes"
-                ),
+                sqlserver=sqlserver_config,
+                mysql=mysql_config,
             ),
             paths=PathConfig(
                 data_dir=paths_dict.get("data_dir", ""),
@@ -156,5 +256,3 @@ class ConfigLoader:
         )
 
 
-# 为了兼容旧代码，导入必要的类型
-from config.schema import ERPConfig, DatabaseConfig, PathConfig, ExtractionConfig, ValidationConfig