目录

如何解决LocalSocket创建报错

问题现象

LocalSocket无法正常使用，常见问题：

  1. 创建LocalSocket报错：2301111 Connection refused。
  2. 创建LocalSocket/LocalSocketServer报错：2301002 No such file or directory。
  3. 客户端发送数据，服务端没有监听到消息。
  4. 服务端开启后立即发送消息，随后服务关闭，导致LocalSocket无法收到对方发送的消息。

背景知识

问题定位

  1. 报错2301111 Connection refused通常需要排查服务端是否可连接，在LocalSocket连接前需要创建并启动LocalSocketServer，并检查LocalAddress是否一致。
  2. 报错2301002 No such file or directory。对于LocalSocketServer，通常是没有本地套接字文件路径的权限，无法自动创建此文件。对于LocalSocket，除检查路径外，需要保证已提前创建LocalSocketServer并调用其listen函数自动创建套接字文件。
  3. 对于服务端无法监听到发送的消息，需要确保LocalSocket客户端在发送数据前，服务端已开启了on('connect')以及回调中连接的on('message')监听。否则服务端没有监听到客户端连接事件，就无法再监听到对应连接的其他事件。
  4. 对于服务端开启后立即发送消息随后服务关闭的问题，需要排查发送消息的时机是否在on('connect')回调之外。如果在回调之外发送消息，此时尚未获得LocalSocketConnection对象，消息无法正确投递，服务关闭后连接断开，导致LocalSocket无法收到对方发送的消息。

分析结论

  1. 2301002 No such file or directory问题：应用没有权限访问LocalAddress的address，或客户端没有使用同一个套接字文件。
  2. 2301111 Connection refused和服务端没有接收到客户端发送的消息问题：使用LocalSocket时没有先启动LocalSocketServer，再启动客户端。
  3. 服务端开启后立即发送消息随后服务关闭问题：在on('connect')回调之外发送消息，此时缺少连接对象LocalSocketConnection，消息发送后服务关闭，导致无法正常通信。

修改建议

  1. LocalAddress的address配置应用沙箱路径，并且客户端和服务端使用同一个套接字文件：
    genLocalAddress(socketFileName: string) {
    let context: common.UIAbilityContext = this.getUIContext().getHostContext() as common.UIAbilityContext;
    let sandboxPath: string = context.filesDir + '/' + socketFileName;
    let localAddress: socket.LocalAddress = {
      address: sandboxPath
    };
    return localAddress;
  }
  2. LocalSocket使用需要先启动LocalSocketServer：
    // 创建并绑定本地套接字文件，进行监听。
          this.server.listen(this.localAddress).then(() => {
            console.info('LocalSocket Server listen success');
          }).catch((err: BusinessError) => {
            console.error('LocalSocket Server listen fail: ' + JSON.stringify(err));
          });

          // 订阅LocalSocketServer的connect事件。
          this.server.on('connect', (connection: socket.LocalSocketConnection) => {
            console.info('LocalSocket Server 监听到客户端连接: ' + JSON.stringify(connection.clientId));
            // 订阅LocalSocketConnection相关的事件。
            connection.on('message', (value: socket.LocalSocketMessageInfo) => {
              console.info('LocalSocket Server total: ' + JSON.stringify(value));
              console.info('LocalSocket Server message information: ' + this.decodeMessage(value));
              // ...
            });

            connection.on('error', (err: BusinessError) => {
              console.error('LocalSocket Server err:' + JSON.stringify(err));
            });

            // 向客户端发送数据。
            this.sendMessage(connection, 'Hello Client!');
            // ...
          });
  3. 再启动LocalSocket客户端发送消息：
    // 启动客户端端前，需要先启动LocalSocketServer，否则报错：2301111 Connection refused
        let connectOpt: socket.LocalConnectOptions = {
          address: this.localAddress,
          timeout: 6000
        };

        this.client.connect(connectOpt).then(() => {
          console.info('LocalSocket Client connect success');
        }).catch((err: BusinessError) => {
          console.error('LocalSocket Client connect fail: ' + JSON.stringify(err));
        });

        this.client.on('message', (value: socket.LocalSocketMessageInfo) => {
          console.info('LocalSocket Server total: ' + JSON.stringify(value));
          console.info('LocalSocket Server message information: ' + this.decodeMessage(value));
        });
        this.client.on('connect', () => {
          console.info('LocalSocket Client on connect');
        });
        this.client.on('close', () => {
          console.info('LocalSocket Client on close');
        });
  4. 确保在on('connect')回调中获得LocalSocketConnection对象后再发送消息，避免在回调之外发送导致消息丢失和服务关闭：
    // 正确做法：在on('connect')回调中获取connection对象后再发送消息
this.server.on('connect', (connection: socket.LocalSocketConnection) => {
  // 在此处获取到LocalSocketConnection对象后发送消息
  this.sendMessage(connection, 'Hello Client!');
});

// 错误做法：在on('connect')回调之外发送消息，此时缺少LocalSocketConnection对象
// this.sendMessage(connection,'Hello Client!'); // connection未定义，消息无法投递

完整示例如下：

import { socket } from '@kit.NetworkKit';
import { common } from '@kit.AbilityKit';
import { util } from '@kit.ArkTS';
import { BusinessError } from '@kit.BasicServicesKit';

@Entry
@Component
struct LocalSocketPage {
  private server: socket.LocalSocketServer = socket.constructLocalSocketServerInstance();
  private client: socket.LocalSocket = socket.constructLocalSocketInstance();
  private localAddress: socket.LocalAddress = this.genLocalAddress('socket_1'); // 创建本地文件，server和client均需对此路径具备访问权限

  // Start solution1
  genLocalAddress(socketFileName: string) {
    let context: common.UIAbilityContext = this.getUIContext().getHostContext() as common.UIAbilityContext;
    let sandboxPath: string = context.filesDir + '/' + socketFileName;
    let localAddress: socket.LocalAddress = {
      address: sandboxPath
    };
    return localAddress;
  }
  // End solution1

  decodeMessage(data: socket.LocalSocketMessageInfo): string {
    if (data?.message) {
      let decoder = util.TextDecoder.create('utf-8');
      let message = decoder.decodeToString(new Uint8Array(data.message));
      return message;
    }
    return '';
  }

  sendMessage(socket: socket.LocalSocket | socket.LocalSocketConnection, message: string): void {
    let sendOpt: socket.LocalSendOptions = {
      data: message
    };
    socket.send(sendOpt).then(() => {
      console.info('LocalSocket send message success');
    }).catch((err: BusinessError) => {
      console.info('LocalSocket send message failed: ' + JSON.stringify(err));
    });
  }

  build() {
    Column({ space: 24 }) {
      Button('启动LocalSocket服务端')
        .onClick(() => {
          // Start solution2
          // 创建并绑定本地套接字文件，进行监听。
          this.server.listen(this.localAddress).then(() => {
            console.info('LocalSocket Server listen success');
          }).catch((err: BusinessError) => {
            console.error('LocalSocket Server listen fail: ' + JSON.stringify(err));
          });

          // 订阅LocalSocketServer的connect事件。
          this.server.on('connect', (connection: socket.LocalSocketConnection) => {
            console.info('LocalSocket Server 监听到客户端连接: ' + JSON.stringify(connection.clientId));
            // 订阅LocalSocketConnection相关的事件。
            connection.on('message', (value: socket.LocalSocketMessageInfo) => {
              console.info('LocalSocket Server total: ' + JSON.stringify(value));
              console.info('LocalSocket Server message information: ' + this.decodeMessage(value));
              // ...
            });

            connection.on('error', (err: BusinessError) => {
              console.error('LocalSocket Server err:' + JSON.stringify(err));
            });

            // 向客户端发送数据。
            this.sendMessage(connection, 'Hello Client!');
            // ...
          });
          // End solution2
        });
      Button('启动LocalSocket客户端').onClick(() => {
        // Start solution3
        // 启动客户端端前，需要先启动LocalSocketServer，否则报错：2301111 Connection refused
        let connectOpt: socket.LocalConnectOptions = {
          address: this.localAddress,
          timeout: 6000
        };

        this.client.connect(connectOpt).then(() => {
          console.info('LocalSocket Client connect success');
        }).catch((err: BusinessError) => {
          console.error('LocalSocket Client connect fail: ' + JSON.stringify(err));
        });

        this.client.on('message', (value: socket.LocalSocketMessageInfo) => {
          console.info('LocalSocket Server total: ' + JSON.stringify(value));
          console.info('LocalSocket Server message information: ' + this.decodeMessage(value));
        });
        this.client.on('connect', () => {
          console.info('LocalSocket Client on connect');
        });
        this.client.on('close', () => {
          console.info('LocalSocket Client on close');
        });
        // End solution3
      });
      Button('客户端发送数据').onClick(() => {
        // 需要服务端先使用on('connect')、on('message')监听到客户端连接，否则无法监听到消息
        this.sendMessage(this.client, 'Hello Server!');
      });
    }
    .height('100%')
    .width('100%');
  }
}