HarmonyOS学习路之开发篇—Java UI框架(JS FA调用Java PA)

JS FA调用Java PA机制

使用兼容JS的类Web开发范式的方舟开发框架提供了JS FA(Feature Ability)调用Java PA(Particle Ability)的机制,该机制提供了一种通道来传递方法调用、处理数据返回以及订阅事件上。

当前提供Ability和Internal Ability两种调用方式。

  • Ability:拥有独立的Ability生命周期,FA使用远端进程通信拉起并请求PA服务,适用于基本服务供多FA调用或者服务在后台独立运行的场景。
  • Internal Ability:与FA共进程,采用内部函数调用的方式和FA进行通信,适用于对服务响应时延要求较高的场景。该方式下PA不支持其他FA访问调用。

    对于Internal Ability调用方式的开发,可以使用工具自动生成代码(自动生成下篇文章详解),提高开发效率。

JS端与Java端通过bundleName和abilityName来进行关联。在系统收到JS调用请求后,根据开发者在JS接口中设置的参数来选择对应的处理方式。开发者在onRemoteRequest()中实现PA提供的业务逻辑。

FA调用PA接口

FA端提供以下三个JS接口:

  • FeatureAbility.callAbility(OBJECT):调用PA能力。
  • FeatureAbility.subscribeAbilityEvent(OBJECT, Function):订阅PA能力。
  • FeatureAbility.unsubscribeAbilityEvent(OBJECT):取消订阅PA能力。

PA端提供以下两类接口:

  • IRemoteObject.onRemoteRequest(int, MessageParcel, MessageParcel, MessageOption):Ability调用方式,FA使用远端进程通信拉起并请求PA服务。
  • AceInternalAbility.AceInternalAbilityHandler.onRemoteRequest(int, MessageParcel, MessageParcel, MessageOption):Internal Ability调用方式,采用内部函数调用的方式和FA进行通信。

FA调用PA常见问题

  • callAbility返回报错:"Internal ability not register."

    返回该错误说明JS接口调用请求未在系统中找到对应的InternalAbilityHandler进行处理,因此需要检查以下几点是否正确执行:

    1. 在AceAbility继承类中对AceInternalAbility继承类执行了register方法,具体注册可参考Internal Ability的示例代码。
    2. JS侧填写的bundleName和abilityName与AceInternalAbility继承类构造函数中填写的名称保持相同,大小写敏感。
    3. 检查JS端填写的abilityType(0:Ability; 1:Internal Ability),确保没有将AbilityType缺省或误填写为Ability方式。

    Ability和Internal Ability是两种不同的FA调用PA的方式。

Ability和InternalAbility差异项

差异项

Ability

InternalAbility

JS端(abilityType)

0

1

是否需要在config.json的abilities中为PA添加声明

需要(有独立的生命周期)

不需要(和FA共生命周期)

是否需要在FA中注册

不需要

需要

继承的类

ohos.aafwk.ability.Ability

ohos.ace.ability.AceInternalAbility

是否允许被其他FA访问调用

  • FeatureAbility.callAbility中syncOption参数说明:
    • 对于JS FA侧,返回的结果都是Promise对象,因此无论该参数取何值,都采用异步方式等待PA侧响应。
    • 对于JAVA PA侧,在Internal Ability方式下收到FA的请求后,根据该参数的取值来选择:通过同步的方式获取结果后返回;或者异步执行PA逻辑,获取结果后使用remoteObject.sendRequest的方式将结果返回FA。
  • 使用await方式调用时IDE编译报错,需引入babel-runtime/regenerator。

示例参考

JS端调用FeatureAbility接口,传入两个Number参数,Java端接收后返回两个数的和。

JS FA应用的JS模块(entry/src/main)的典型开发目录结构如下:

HarmonyOS学习路之开发篇—Java UI框架(JS FA调用Java PA)_第1张图片

  • FA JavaScript端

使用Internal Ability方式时,需要将对应的action.abilityType值改为ABILITY_TYPE_INTERNAL。

// abilityType: 0-Ability; 1-Internal Ability
const ABILITY_TYPE_EXTERNAL = 0;
const ABILITY_TYPE_INTERNAL = 1;
// syncOption(Optional, default sync): 0-Sync; 1-Async
const ACTION_SYNC = 0;
const ACTION_ASYNC = 1;
const ACTION_MESSAGE_CODE_PLUS = 1001;
export default {
  plus: async function() {
    var actionData = {};
    actionData.firstNum = 1024;
    actionData.secondNum = 2048;

    var action = {};
    action.bundleName = 'com.example.hiaceservice';
    action.abilityName = 'com.example.hiaceservice.ComputeServiceAbility';
    action.messageCode = ACTION_MESSAGE_CODE_PLUS;
    action.data = actionData;
    action.abilityType = ABILITY_TYPE_EXTERNAL;
    action.syncOption = ACTION_SYNC;

    var result = await FeatureAbility.callAbility(action);
    var ret = JSON.parse(result);
    if (ret.code == 0) {
      console.info('plus result is:' + JSON.stringify(ret.abilityResult));
    } else {
      console.error('plus error code:' + JSON.stringify(ret.code));
    }
  }
}
  • PA端(Ability方式)

功能代码实现:

在java目录下新建一个Service Ability,文件命名为ComputeServiceAbility.java

package com.example.hiaceservice;

// ohos相关接口包
import ohos.aafwk.ability.Ability;
import ohos.aafwk.content.Intent;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;
import ohos.rpc.IRemoteBroker;
import ohos.rpc.IRemoteObject;
import ohos.rpc.RemoteObject;
import ohos.rpc.MessageParcel;
import ohos.rpc.MessageOption;
import ohos.utils.zson.ZSONObject;

import java.util.HashMap;
import java.util.Map;
 
public class ComputeServiceAbility extends Ability {
  // 定义日志标签
  private static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0, "MY_TAG");

  private MyRemote remote = new MyRemote();
  // FA在请求PA服务时会调用Ability.connectAbility连接PA,连接成功后,需要在onConnect返回一个remote对象,供FA向PA发送消息
  @Override
  protected IRemoteObject onConnect(Intent intent) {
    super.onConnect(intent);
    return remote.asObject();
  }
  class MyRemote extends RemoteObject implements IRemoteBroker {
    private static final int SUCCESS = 0;
    private static final int ERROR = 1;
    private static final int PLUS = 1001;   

    MyRemote() {
      super("MyService_MyRemote");
    }
 
    @Override
    public boolean onRemoteRequest(int code, MessageParcel data, MessageParcel reply, MessageOption option) {
      switch (code) {
        case PLUS: {
          String dataStr = data.readString();
          RequestParam param = new RequestParam();
          try {    
              param = ZSONObject.stringToClass(dataStr, RequestParam.class);
          } catch (RuntimeException e) {    
              HiLog.error(LABEL, "convert failed.");
          }
                    
          // 返回结果当前仅支持String,对于复杂结构可以序列化为ZSON字符串上报
          Map result = new HashMap();
          result.put("code", SUCCESS);
          result.put("abilityResult", param.getFirstNum() + param.getSecondNum());
          reply.writeString(ZSONObject.toZSONString(result));
          break;
        }
        default: {
          Map result = new HashMap();
          result.put("abilityError", ERROR);
          reply.writeString(ZSONObject.toZSONString(result));
          return false;
        }
      }
      return true;
    }
 
    @Override
    public IRemoteObject asObject() {
      return this;
    }
  }
}

请求参数代码:

RequestParam.java

public class RequestParam {
  private int firstNum;
  private int secondNum;

  public int getFirstNum() {
    return firstNum;
  }

  public void setFirstNum(int firstNum) {
    this.firstNum = firstNum;
  }

  public int getSecondNum() {
    return secondNum;
  }

  public void setSecondNum(int secondNum) {
    this.secondNum = secondNum;
  }
}

PA端(Internal Ability方式)

功能代码实现(以下代码可以使用工具自动生成):

在java目录下新建一个Service Ability,文件命名为ComputeInternalAbility.java

package com.example.hiaceservice;

// ohos相关接口包
import ohos.ace.ability.AceInternalAbility;
import ohos.app.AbilityContext;
import ohos.hiviewdfx.HiLog;
import ohos.hiviewdfx.HiLogLabel;
import ohos.rpc.IRemoteObject;
import ohos.rpc.MessageOption;
import ohos.rpc.MessageParcel;
import ohos.rpc.RemoteException;
import ohos.utils.zson.ZSONObject;

import java.util.HashMap;
import java.util.Map;

public class ComputeInternalAbility extends AceInternalAbility {
  private static final String BUNDLE_NAME = "com.example.hiaceservice";
  private static final String ABILITY_NAME = "com.example.hiaceservice.ComputeInternalAbility";
  private static final int SUCCESS = 0;
  private static final int ERROR = 1;
  private static final int PLUS = 1001;
  // 定义日志标签
  private static final HiLogLabel LABEL = new HiLogLabel(HiLog.LOG_APP, 0, "MY_TAG");

  private static ComputeInternalAbility instance;
  private AbilityContext abilityContext;

  // 如果多个Ability实例都需要注册当前InternalAbility实例,需要更改构造函数,设定自己的bundleName和abilityName
  public ComputeInternalAbility() {
    super(BUNDLE_NAME, ABILITY_NAME);
  }

  public boolean onRemoteRequest(int code, MessageParcel data, MessageParcel reply, MessageOption option) {
    switch (code) {
      case PLUS: {
        String dataStr = data.readString();
        RequestParam param = new RequestParam();
        try {    
            param = ZSONObject.stringToClass(dataStr, RequestParam.class);
        } catch (RuntimeException e) {    
            HiLog.error(LABEL, "convert failed.");
        }

        // 返回结果当前仅支持String,对于复杂结构可以序列化为ZSON字符串上报
        Map result = new HashMap();
        result.put("code", SUCCESS);
        result.put("abilityResult", param.getFirstNum() + param.getSecondNum());
        // SYNC
        if (option.getFlags() == MessageOption.TF_SYNC) {
          reply.writeString(ZSONObject.toZSONString(result));
        } else {
          // ASYNC
          MessageParcel responseData = MessageParcel.obtain();
          responseData.writeString(ZSONObject.toZSONString(result));
          IRemoteObject remoteReply = reply.readRemoteObject();
          try {
            remoteReply.sendRequest(0, responseData, MessageParcel.obtain(), new MessageOption());
          } catch (RemoteException exception) {
              return false;
          } finally {
              responseData.reclaim();
          }
        }
        break;
      }
      default: {
        Map result = new HashMap();
        result.put("abilityError", ERROR);
        reply.writeString(ZSONObject.toZSONString(result));
        return false;
      }
    }
    return true;
  }

  /**
  * Internal ability 注册接口。
  */
  public static void register(AbilityContext abilityContext) {
    instance = new ComputeInternalAbility();
    instance.onRegister(abilityContext);
  }

  private void onRegister(AbilityContext abilityContext) {
    this.abilityContext = abilityContext;
    this.setInternalAbilityHandler((code, data, reply, option) -> {
      return this.onRemoteRequest(code, data, reply, option);
    });
  }

  /**
   * Internal ability 注销接口。
   */
  public static void unregister() {
    instance.onUnregister();
  }

  private void onUnregister() {
    abilityContext = null;
    this.setInternalAbilityHandler(null);
  }
}

Internal Ability注册:修改继承AceAbility工程中的代码

public class MainAbility extends AceAbility {
 
  @Override
  public void onStart(Intent intent) {
    // 注册, 如果需要在Page初始化(onInit或之前)时调用AceInternalAbility的能力,注册操作需要在super.onStart之前进行
    ComputeInternalAbility.register(this);
    ...
    super.onStart(intent);
  }
  @Override 
  public void onStop() {
    // 注销
    ComputeInternalAbility.unregister();     
    super.onStop();
  }
}

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