feat: 新增 MySQL 数据库驱动支持，支持跨设备数据同步

backend/internal/database/database.go

@@ -0,0 +1,126 @@
+package database
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/pressly/goose/v3"
+	"go.uber.org/zap"
+	"gorm.io/driver/mysql"
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+	"gorm.io/gorm/logger"
+
+	"nex/backend/internal/config"
+)
+
+func Init(cfg *config.DatabaseConfig, zapLogger *zap.Logger) (*gorm.DB, error) {
+	db, err := initDB(cfg)
+	if err != nil {
+		return nil, fmt.Errorf("初始化数据库失败: %w", err)
+	}
+
+	if err := runMigrations(db, cfg.Driver); err != nil {
+		return nil, fmt.Errorf("数据库迁移失败: %w", err)
+	}
+
+	configurePool(db, cfg)
+
+	return db, nil
+}
+
+func Close(db *gorm.DB) {
+	sqlDB, err := db.DB()
+	if err != nil {
+		return
+	}
+	sqlDB.Close()
+}
+
+func initDB(cfg *config.DatabaseConfig) (*gorm.DB, error) {
+	gormConfig := &gorm.Config{
+		Logger: logger.Default.LogMode(logger.Info),
+	}
+
+	switch cfg.Driver {
+	case "mysql":
+		dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=true&loc=Local",
+			cfg.User, cfg.Password, cfg.Host, cfg.Port, cfg.DBName)
+		return gorm.Open(mysql.Open(dsn), gormConfig)
+	default:
+		dbDir := filepath.Dir(cfg.Path)
+		if err := os.MkdirAll(dbDir, 0755); err != nil {
+			return nil, fmt.Errorf("创建数据库目录失败: %w", err)
+		}
+		return gorm.Open(sqlite.Open(cfg.Path), gormConfig)
+	}
+}
+
+func runMigrations(db *gorm.DB, driver string) error {
+	sqlDB, err := db.DB()
+	if err != nil {
+		return err
+	}
+
+	migrationsDir := getMigrationsDir(driver)
+	if _, err := os.Stat(migrationsDir); os.IsNotExist(err) {
+		return fmt.Errorf("迁移目录不存在: %s", migrationsDir)
+	}
+
+	gooseDialect := "sqlite3"
+	migrationsSubDir := "sqlite"
+	if driver == "mysql" {
+		gooseDialect = "mysql"
+		migrationsSubDir = "mysql"
+	}
+
+	goose.SetDialect(gooseDialect)
+	if err := goose.Up(sqlDB, migrationsDir); err != nil {
+		return err
+	}
+
+	log.Printf("使用 %s 方言执行迁移，目录: %s", gooseDialect, migrationsSubDir)
+	return nil
+}
+
+func configurePool(db *gorm.DB, cfg *config.DatabaseConfig) {
+	if cfg.Driver == "sqlite" {
+		if err := db.Exec("PRAGMA journal_mode=WAL").Error; err != nil {
+			log.Printf("警告: 启用 WAL 模式失败: %v", err)
+		}
+	}
+
+	sqlDB, err := db.DB()
+	if err != nil {
+		return
+	}
+	sqlDB.SetMaxIdleConns(cfg.MaxIdleConns)
+	sqlDB.SetMaxOpenConns(cfg.MaxOpenConns)
+	sqlDB.SetConnMaxLifetime(cfg.ConnMaxLifetime)
+
+	log.Printf("数据库连接池配置: MaxIdle=%d, MaxOpen=%d, MaxLifetime=%v",
+		cfg.MaxIdleConns, cfg.MaxOpenConns, cfg.ConnMaxLifetime)
+}
+
+func getMigrationsDir(driver string) string {
+	_, filename, _, ok := runtime.Caller(0)
+	if ok {
+		subDir := "sqlite"
+		if driver == "mysql" {
+			subDir = "mysql"
+		}
+		dir := filepath.Join(filepath.Dir(filename), "..", "..", "migrations", subDir)
+		if abs, err := filepath.Abs(dir); err == nil {
+			return abs
+		}
+	}
+	return "./migrations"
+}
+
+func BuildDSN(cfg *config.DatabaseConfig) string {
+	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8mb4&parseTime=true&loc=Local",
+		cfg.User, cfg.Password, cfg.Host, cfg.Port, cfg.DBName)
+}

backend/internal/database/database_test.go

@@ -0,0 +1,75 @@
+package database
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"nex/backend/internal/config"
+)
+
+func TestInit_SQLite(t *testing.T) {
+	dir := t.TempDir()
+	cfg := &config.DatabaseConfig{
+		Driver:          "sqlite",
+		Path:            filepath.Join(dir, "test.db"),
+		MaxIdleConns:    5,
+		MaxOpenConns:    10,
+		ConnMaxLifetime: 0,
+	}
+
+	db, err := Init(cfg, nil)
+	require.NoError(t, err)
+	require.NotNil(t, db)
+	defer Close(db)
+
+	sqlDB, err := db.DB()
+	require.NoError(t, err)
+	require.NotNil(t, sqlDB)
+}
+
+func TestClose(t *testing.T) {
+	dir := t.TempDir()
+	cfg := &config.DatabaseConfig{
+		Driver:          "sqlite",
+		Path:            filepath.Join(dir, "test.db"),
+		MaxIdleConns:    5,
+		MaxOpenConns:    10,
+		ConnMaxLifetime: 0,
+	}
+
+	db, err := Init(cfg, nil)
+	require.NoError(t, err)
+	require.NotNil(t, db)
+
+	Close(db)
+}
+
+func TestBuildDSN(t *testing.T) {
+	cfg := &config.DatabaseConfig{
+		Driver:   "mysql",
+		Host:     "db.example.com",
+		Port:     3306,
+		User:     "nexuser",
+		Password: "secretpass",
+		DBName:   "nexdb",
+	}
+
+	dsn := BuildDSN(cfg)
+	assert.Equal(t, "nexuser:secretpass@tcp(db.example.com:3306)/nexdb?charset=utf8mb4&parseTime=true&loc=Local", dsn)
+}
+
+func TestBuildDSN_EmptyPassword(t *testing.T) {
+	cfg := &config.DatabaseConfig{
+		Driver: "mysql",
+		Host:   "localhost",
+		Port:   3306,
+		User:   "root",
+		DBName: "nex",
+	}
+
+	dsn := BuildDSN(cfg)
+	assert.Equal(t, "root:@tcp(localhost:3306)/nex?charset=utf8mb4&parseTime=true&loc=Local", dsn)
+}