IDL接口描述语言-传递Sequenceable对象示例

HarmonyOS IDL（HarmonyOS Interface Definition Language)

客户端和服务端定义双方都认可的通信接口

• 面向应用程序的北向接口
• 面向硬件设备的南向接口

IPC/RPC通信模型

模型说明:

• 服务端提供服务接口，通过继承编译生成的桩(Stub)类。
• 客户端调用编译时生成的代理类(Proxy)

使用IDL相互通信的优势:

• 以接口的形式定义服务，隐藏实现细节
• 支持跨设备/跨进程调用

基本数据类型

Sequenceable数据类型

Sequenceable数据类型是指用“Sequenceable”关键字声明的非基本数据类型，表明该数据类型可以通过Parcel进行跨进程（或跨设备）传递。

数组类型

容器类型

服务端实现步骤

1. 自定义对象实现Sequenceable接口

   package ohos.samples.rpcserver.model;
   
   import ohos.utils.Parcel;
   import ohos.utils.Sequenceable;
   
   public class SequenceableData implements Sequenceable {
   
       private int numA = 0;
       private int numB = 0;
   
       public SequenceableData() {
       }
   
       public SequenceableData(int numA, int numB) {
           this.numA = numA;
           this.numB = numB;
       }
   
       
       @Override
       public boolean marshalling(Parcel out) {
           // 将数据写入到out中
           return out.writeInt(numA) && out.writeInt(numB);
       }
   
       
       @Override
       public boolean unmarshalling(Parcel in) {
           // 根据marshalling方法中写入的顺序从in中读取数据
           this.numA = in.readInt();
           this.numB = in.readInt();
           return true;
       }
   
       public int getNumA() {
           return numA;
       }
   
       public int getNumB() {
           return numB;
       }
   
   }

2. 定义IDL文件，然后gradle中执行compileDebugIdl编译idl文件

   sequenceable ohos.samples.rpcserver.model.SequenceableData;
   
   interface ohos.samples.rpcserver.IMyIdlInterface {
       int addNumber([in] SequenceableData sequenceableData);
   }

3. 服务端实现idl接口

   package ohos.samples.rpcserver;
   
   import ohos.aafwk.ability.Ability;
   import ohos.aafwk.content.Intent;
   import ohos.rpc.IRemoteObject;
   import ohos.rpc.RemoteException;
   import ohos.samples.rpcserver.model.SequenceableData;
   
   
   public class ServiceAbility extends Ability {
       @Override
       protected IRemoteObject onConnect(Intent intent) {
           return new IMyIdlInterfaceStubImpl("starting IMyIdlInterface");
       }
       private static class IMyIdlInterfaceStubImpl extends MyIdlInterfaceStub {
   
           public IMyIdlInterfaceStubImpl(String descriptor) {
               super(descriptor);
           }
   
           @Override
           public int addNumber(SequenceableData sequenceableData) throws RemoteException {
               LogUtil.info("","numA+numB=" + (sequenceableData.getNumA() + sequenceableData.getNumB()));
               return sequenceableData.getNumA() + sequenceableData.getNumB();
           }
       }
   }

客户端实现步骤

1.  复制Server端实现Sequenceable接口的对象到客户端项目。
    注意：包名和类名需要跟服务端的对象保持一致。
2. 复制ServerIDL接口文件到客户端项目中，然后gradle中执行compileDebugIdl。 |
   注意：接口的包名和idl文件名需要跟服务端idl文件保持一致。
3. 客户端连接服务端

   private MyIdlInterfaceProxy myIdlInterfaceProxy;
   
   private void startServer() {
       Intent intent = new Intent();
       ElementName elementName = new ElementName("", "ohos.samples.rpcserver",
               "ohos.samples.rpcserver.ServiceAbility");
       intent.setElement(elementName);
       connectAbility(intent, connection);
   }
   
   private final IAbilityConnection connection = new IAbilityConnection() {
       @Override
       public void onAbilityConnectDone(ElementName elementName, IRemoteObject remoteObject, int resultCode) {
           myIdlInterfaceProxy = new MyIdlInterfaceProxy(remoteObject);
       }
   
       @Override
       public void onAbilityDisconnectDone(ElementName elementName, int resultCode) {
       }
   };

4. 客户端调用服务端IDL接口

   private void addNumbers() {
       try {
           int sum = myIdlInterfaceProxy.addNumber(new SequenceableData(firstNumber,secondNumber));
       } catch (RemoteException | NumberFormatException e) {
           LogUtil.error(TAG, "Remote Exception or Number Format Exception");
       }
   }