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docs/nestjs_guide.md
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docs/nestjs_guide.md
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# NestJS 使用指南
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本文档提供 NestJS 在游戏后端开发中的常用模式和最佳实践。
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## 目录
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- [核心概念](#核心概念)
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- [模块化开发](#模块化开发)
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- [控制器与路由](#控制器与路由)
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- [服务与依赖注入](#服务与依赖注入)
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- [WebSocket 实时通信](#websocket-实时通信)
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- [数据验证](#数据验证)
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- [异常处理](#异常处理)
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## 核心概念
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NestJS 采用模块化架构，主要由以下几个部分组成：
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- **Module（模块）**：组织代码的基本单元
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- **Controller（控制器）**：处理 HTTP 请求
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- **Provider（提供者）**：包括 Service、Repository 等，处理业务逻辑
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- **Gateway（网关）**：处理 WebSocket 连接
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## 模块化开发
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### 创建游戏模块
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使用 NestJS CLI 快速生成模块：
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```bash
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nest g module game
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nest g controller game
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nest g service game
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```
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### 模块示例
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```typescript
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// src/game/game_module.ts
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import { Module } from '@nestjs/common';
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import { GameController } from './game_controller';
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import { GameService } from './game_service';
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@Module({
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controllers: [GameController],
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providers: [GameService],
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exports: [GameService], // 导出供其他模块使用
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})
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export class GameModule {}
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```
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在根模块中导入：
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```typescript
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// src/app_module.ts
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import { Module } from '@nestjs/common';
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import { GameModule } from './game/game_module';
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@Module({
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imports: [GameModule],
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})
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export class AppModule {}
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```
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## 控制器与路由
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控制器负责处理 HTTP 请求，定义 RESTful API。
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### 基础控制器示例
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```typescript
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// src/api/player_controller.ts
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import { Controller, Get, Post, Body, Param } from '@nestjs/common';
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import { PlayerService } from '../service/player_service';
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import { CreatePlayerDto } from '../model/dto/create_player_dto';
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@Controller('api/players')
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export class PlayerController {
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constructor(private readonly playerService: PlayerService) {}
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// GET /api/players
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@Get()
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findAll() {
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return this.playerService.findAll();
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}
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// GET /api/players/:id
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@Get(':id')
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findOne(@Param('id') id: string) {
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return this.playerService.findOne(id);
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}
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// POST /api/players
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@Post()
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create(@Body() createPlayerDto: CreatePlayerDto) {
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return this.playerService.create(createPlayerDto);
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}
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}
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```
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### 常用装饰器
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- `@Get()`, `@Post()`, `@Put()`, `@Delete()` - HTTP 方法
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- `@Param()` - 路由参数
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- `@Body()` - 请求体
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- `@Query()` - 查询参数
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- `@Headers()` - 请求头
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## 服务与依赖注入
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服务层包含业务逻辑，通过依赖注入使用。
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### 服务示例
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```typescript
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// src/service/player_service.ts
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import { Injectable } from '@nestjs/common';
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import { CreatePlayerDto } from '../model/dto/create_player_dto';
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import { Player } from '../model/player_entity';
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@Injectable()
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export class PlayerService {
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private players: Player[] = [];
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findAll(): Player[] {
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return this.players;
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}
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findOne(id: string): Player {
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return this.players.find(player => player.id === id);
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}
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create(createPlayerDto: CreatePlayerDto): Player {
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const player: Player = {
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id: Date.now().toString(),
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...createPlayerDto,
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createdAt: new Date(),
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};
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this.players.push(player);
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return player;
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}
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updatePosition(id: string, x: number, y: number): Player {
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const player = this.findOne(id);
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if (player) {
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player.x = x;
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player.y = y;
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}
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return player;
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}
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}
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```
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## WebSocket 实时通信
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游戏需要实时通信，使用 WebSocket Gateway。
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### 安装依赖
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```bash
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yarn add @nestjs/websockets @nestjs/platform-socket.io socket.io
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```
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### Gateway 示例
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```typescript
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// src/api/game_gateway.ts
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import {
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WebSocketGateway,
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WebSocketServer,
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SubscribeMessage,
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OnGatewayConnection,
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OnGatewayDisconnect,
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} from '@nestjs/websockets';
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import { Server, Socket } from 'socket.io';
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@WebSocketGateway({
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cors: {
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origin: '*',
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},
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})
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export class GameGateway implements OnGatewayConnection, OnGatewayDisconnect {
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@WebSocketServer()
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server: Server;
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// 玩家连接
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handleConnection(client: Socket) {
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console.log(`Player connected: ${client.id}`);
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}
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// 玩家断开
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handleDisconnect(client: Socket) {
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console.log(`Player disconnected: ${client.id}`);
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}
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// 监听玩家移动事件
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@SubscribeMessage('player-move')
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handlePlayerMove(client: Socket, payload: { x: number; y: number }) {
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// 广播给所有其他玩家
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client.broadcast.emit('player-moved', {
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playerId: client.id,
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x: payload.x,
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y: payload.y,
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});
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return { success: true };
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}
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// 监听玩家攻击事件
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@SubscribeMessage('player-attack')
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handlePlayerAttack(client: Socket, payload: { targetId: string }) {
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// 发送给特定玩家
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this.server.to(payload.targetId).emit('attacked', {
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attackerId: client.id,
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});
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return { success: true };
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}
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// 服务器主动推送游戏状态
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broadcastGameState(gameState: any) {
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this.server.emit('game-state', gameState);
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}
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}
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```
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### 在模块中注册
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```typescript
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// src/game/game_module.ts
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import { Module } from '@nestjs/common';
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import { GameGateway } from '../api/game_gateway';
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import { GameService } from '../service/game_service';
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@Module({
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providers: [GameGateway, GameService],
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})
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export class GameModule {}
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```
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## 数据验证
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使用 DTO（Data Transfer Object）和 class-validator 进行数据验证。
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### 安装依赖
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```bash
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yarn add class-validator class-transformer
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```
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### DTO 示例
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```typescript
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// src/model/dto/create_player_dto.ts
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import { IsString, IsNotEmpty, MinLength, MaxLength } from 'class-validator';
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export class CreatePlayerDto {
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@IsString()
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@IsNotEmpty()
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@MinLength(3)
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@MaxLength(20)
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name: string;
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@IsString()
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avatar?: string;
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}
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```
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### 启用全局验证管道
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```typescript
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// src/main.ts
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import { NestFactory } from '@nestjs/core';
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import { ValidationPipe } from '@nestjs/common';
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import { AppModule } from './app.module';
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async function bootstrap() {
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const app = await NestFactory.create(AppModule);
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// 启用全局验证
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app.useGlobalPipes(new ValidationPipe({
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whitelist: true, // 自动移除非白名单属性
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forbidNonWhitelisted: true, // 存在非白名单属性时抛出错误
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transform: true, // 自动转换类型
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}));
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await app.listen(3000);
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}
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bootstrap();
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```
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## 异常处理
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### 使用内置异常
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```typescript
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import { Injectable, NotFoundException } from '@nestjs/common';
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@Injectable()
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export class PlayerService {
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findOne(id: string): Player {
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const player = this.players.find(p => p.id === id);
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if (!player) {
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throw new NotFoundException(`Player with ID ${id} not found`);
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}
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return player;
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}
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}
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```
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### 常用异常类型
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- `BadRequestException` - 400
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- `UnauthorizedException` - 401
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- `NotFoundException` - 404
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- `ForbiddenException` - 403
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- `InternalServerErrorException` - 500
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### 自定义异常过滤器
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```typescript
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// src/utils/http_exception_filter.ts
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import {
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ExceptionFilter,
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Catch,
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ArgumentsHost,
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HttpException,
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} from '@nestjs/common';
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import { Response } from 'express';
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@Catch(HttpException)
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export class HttpExceptionFilter implements ExceptionFilter {
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catch(exception: HttpException, host: ArgumentsHost) {
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const ctx = host.switchToHttp();
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const response = ctx.getResponse<Response>();
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const status = exception.getStatus();
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response.status(status).json({
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statusCode: status,
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timestamp: new Date().toISOString(),
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message: exception.message,
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});
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}
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}
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```
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## 实战案例：房间系统
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### 数据模型
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```typescript
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// src/model/room_entity.ts
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export interface Room {
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id: string;
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name: string;
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maxPlayers: number;
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players: string[];
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status: 'waiting' | 'playing' | 'finished';
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createdAt: Date;
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}
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```
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### 服务层
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```typescript
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// src/service/room_service.ts
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import { Injectable, BadRequestException } from '@nestjs/common';
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import { Room } from '../model/room_entity';
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@Injectable()
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export class RoomService {
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private rooms: Map<string, Room> = new Map();
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createRoom(name: string, maxPlayers: number): Room {
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const room: Room = {
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id: Date.now().toString(),
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name,
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maxPlayers,
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players: [],
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status: 'waiting',
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createdAt: new Date(),
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};
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this.rooms.set(room.id, room);
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return room;
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}
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joinRoom(roomId: string, playerId: string): Room {
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const room = this.rooms.get(roomId);
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if (!room) {
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throw new BadRequestException('Room not found');
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}
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if (room.players.length >= room.maxPlayers) {
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throw new BadRequestException('Room is full');
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}
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if (room.status !== 'waiting') {
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throw new BadRequestException('Game already started');
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}
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room.players.push(playerId);
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return room;
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}
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leaveRoom(roomId: string, playerId: string): void {
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const room = this.rooms.get(roomId);
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if (room) {
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room.players = room.players.filter(id => id !== playerId);
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if (room.players.length === 0) {
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this.rooms.delete(roomId);
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}
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}
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}
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listRooms(): Room[] {
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return Array.from(this.rooms.values());
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}
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}
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```
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### 控制器
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```typescript
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// src/api/room_controller.ts
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import { Controller, Get, Post, Body, Param } from '@nestjs/common';
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import { RoomService } from '../service/room_service';
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@Controller('api/rooms')
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export class RoomController {
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constructor(private readonly roomService: RoomService) {}
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@Get()
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listRooms() {
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return this.roomService.listRooms();
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}
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@Post()
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createRoom(@Body() body: { name: string; maxPlayers: number }) {
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return this.roomService.createRoom(body.name, body.maxPlayers);
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}
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@Post(':id/join')
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joinRoom(@Param('id') id: string, @Body() body: { playerId: string }) {
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return this.roomService.joinRoom(id, body.playerId);
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}
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}
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```
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## 最佳实践
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1. **模块化设计**：按功能划分模块（player、room、game 等）
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2. **分层架构**：Controller → Service → Data，职责清晰
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3. **使用 DTO**：定义清晰的数据传输对象，启用验证
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4. **依赖注入**：充分利用 NestJS 的 DI 系统
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5. **异常处理**：使用内置异常类，提供友好的错误信息
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6. **配置管理**：使用 @nestjs/config 管理环境变量
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7. **日志记录**：使用内置 Logger 或集成第三方日志库
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8. **测试**：编写单元测试和 E2E 测试
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## 更多资源
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- [NestJS 官方文档](https://docs.nestjs.com/)
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- [NestJS 中文文档](https://docs.nestjs.cn/)
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- [Socket.IO 文档](https://socket.io/docs/)
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