自定义类如何实现序列化

import rpc from '@ohos.rpc'; 
import hilog from '@ohos.hilog'; 
import UIAbility from '@ohos.app.ability.UIAbility'; 
import AbilityConstant from '@ohos.app.ability.AbilityConstant'; 
 
class MyParcelable implements rpc.Parcelable { 
  num: number = 0; 
  str: string = ''; 
 
  constructor(num: number, str: string) { 
    this.num = num; 
    this.str = str; 
  } 
 
  marshalling(messageSequence: rpc.MessageSequence): boolean { 
    messageSequence.writeInt(this.num); 
    messageSequence.writeString(this.str); 
    return true; 
  } 
 
  unmarshalling(messageSequence: rpc.MessageSequence): boolean { 
    this.num = messageSequence.readInt(); 
    this.str = messageSequence.readString(); 
    return true; 
  } 
} 
 
let parcelable = new MyParcelable(1, "aaa"); 
let data = rpc.MessageSequence.create(); 
let result = data.writeParcelable(parcelable); 
hilog.info(0x0000, 'testTag', 'RpcClient: writeParcelable is ' + result); 
let ret = new MyParcelable(0, ""); 
let result2 = data.readParcelable(ret); 
hilog.info(0x0000, 'testTag', 'RpcClient: readParcelable is ' + result2); 
 
class MyUIAbility extends UIAbility { 
  onMemoryLevel(level: AbilityConstant.MemoryLevel) { 
    console.log(`onMemoryLevel, level: ${JSON.stringify(level)}`); 
  } 
}