应用框架设计

OpenHarmony应用采用分层架构设计，包含UI层、业务逻辑层、数据访问层和网络层。UI层使用ArkTS编写，业务逻辑层处理数据转换和交互逻辑，数据访问层封装SQL操作，网络层负责WiFi通信与远程数据库连接。

权限配置

在config.json中声明网络权限和WiFi权限：

{
  "module": {
    "reqPermissions": [
      {
        "name": "ohos.permission.INTERNET"
      },
      {
        "name": "ohos.permission.GET_WIFI_INFO"
      }
    ]
  }
}

网络连接模块

实现WiFi状态检测与数据库连接管理：

import wifi from '@ohos.wifi';
import http from '@ohos.net.http';

class NetworkManager {
  private static instance: NetworkManager;
  private httpRequest: http.HttpRequest;

  private constructor() {
    this.httpRequest = http.createHttp();
  }

  public static getInstance(): NetworkManager {
    if (!NetworkManager.instance) {
      NetworkManager.instance = new NetworkManager();
    }
    return NetworkManager.instance;
  }

  async checkWifiConnected(): Promise<boolean> {
    const info = await wifi.getLinkedInfo();
    return info.ssid !== null;
  }

  async queryDatabase(sql: string): Promise<string> {
    const url = "http://your-database-server.com/api/query";
    return new Promise((resolve, reject) => {
      this.httpRequest.request(
        url,
        {
          method: http.RequestMethod.POST,
          header: { 'Content-Type': 'application/json' },
          extraData: { sql: sql }
        },
        (err, data) => {
          if (err) {
            reject(err);
          } else {
            resolve(data.result);
          }
        }
      );
    });
  }
}

数据模型定义

定义与数据库字段对应的数据模型：

class User {
  userId: number;
  userName: string;
  userAge: number;

  constructor(data: any) {
    this.userId = data.id || 0;
    this.userName = data.name || '';
    this.userAge = data.age || 0;
  }
}

UI界面实现

使用ArkUI实现数据展示页面：

@Entry
@Component
struct QueryPage {
  @State users: User[] = [];
  @State sql: string = 'SELECT * FROM users WHERE age > 20';

  async queryData() {
    try {
      const netMgr = NetworkManager.getInstance();
      const isConnected = await netMgr.checkWifiConnected();
      if (!isConnected) {
        prompt.showToast({ message: '请连接WiFi' });
        return;
      }

      const result = await netMgr.queryDatabase(this.sql);
      this.users = JSON.parse(result).map((item: any) => new User(item));
    } catch (error) {
      prompt.showToast({ message: `查询失败: ${error.message}` });
    }
  }

  build() {
    Column() {
      TextInput({ text: this.sql })
        .onChange((value: string) => {
          this.sql = value;
        })

      Button('执行查询')
        .onClick(() => this.queryData())

      List({ space: 10 }) {
        ForEach(this.users, (user: User) => {
          ListItem() {
            Column() {
              Text(`ID: ${user.userId}`)
              Text(`姓名: ${user.userName}`)
              Text(`年龄: ${user.userAge}`)
            }
          }
        })
      }
    }
  }
}

服务端接口示例（PHP）

远程服务器需提供API接口处理SQL请求：

<?php
header("Content-Type: application/json");
$db = new PDO('mysql:host=localhost;dbname=test', 'username', 'password');

$data = json_decode(file_get_contents('php://input'), true);
$sql = $data['sql'];

try {
    $stmt = $db->query($sql);
    $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
    echo json_encode($result);
} catch (PDOException $e) {
    http_response_code(500);
    echo json_encode(['error' => $e->getMessage()]);
}
?>

安全增强措施

1. 使用HTTPS加密通信
2. 实现SQL注入防护：

function validateSql(sql: string): boolean {
  const forbidden = ['DROP', 'DELETE', 'UPDATE', 'INSERT'];
  return !forbidden.some(cmd => sql.toUpperCase().includes(cmd));
}

1. 添加请求超时处理：

this.httpRequest.request(
  url,
  {
    method: http.RequestMethod.POST,
    header: { 'Content-Type': 'application/json' },
    extraData: { sql: sql },
    connectTimeout: 10000,
    readTimeout: 10000
  },
  // ...回调处理
);

性能优化建议

1. 实现本地缓存机制
2. 使用分页查询减少数据传输量
3. 添加加载状态指示器
4. 实现自动重连机制

该框架完整实现了从WiFi检测到远程数据库查询的全流程，核心代码约200行，实际开发中可根据具体业务需求扩展更多功能模块。