Ability之间或者进程间数据传递之对象（Sequenceable序列化）原创精华

开源夏德旺

发布于 2021-2-26 13:55

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这两天51cto上的一个粉丝朋友问了我一个问题，Ability之间使用Sequenceable序列化传递数据，如何传递Uri类型数据？网上确实也没有介绍这个使用的demo，为了帮他解决问题，自己帮他写了一个demo，顺手发布一篇博客和源代码。

seralizable是在java api中的类，用它也可以实现序列化，而在android中也有一个类使对象序列化，那就是parcelable，而在HarmonyOS中用Sequenceable来进行序列化。

那么它们之间有什么区别呢？

seralizable:序列化到本地，是一个持久化的操作，效率慢一点

parcelable:只存在于内存，程序结束，序列化后的对象就不存在了。效率快一点
Sequenceable：等同parcelable在Android中的作用。

下面我编写两个AbilitySlice之间互相跳转来传递数据

MainAbilitySlice对应的布局文件代码如下：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:text_helloworld"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$graphic:background_ability_main"
        ohos:layout_alignment="horizontal_center"
        ohos:text="Hello World"
        ohos:text_size="50"
    />

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就是系统自动生成的helloworld，我偷懒就没修改了，核心不在这里。

再创建一个TestSlice，布局代码如下：

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="vertical">

    <Text
        ohos:id="$+id:text_helloworld"
        ohos:height="match_content"
        ohos:width="match_content"
        ohos:background_element="$graphic:background_ability_main"
        ohos:layout_alignment="horizontal_center"
        ohos:text="TEST"
        ohos:text_size="50"
    />

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为了要在两个Slice中间传递一个序列化对象数据，需要先创建一个实体类，并且实现Sequenceable接口，这里才是整个的核心代码，如下：

package com.xdw.sequencedemo;

import ohos.utils.Parcel;
import ohos.utils.Sequenceable;
import ohos.utils.net.Uri;

/**
 * Created by 夏德旺 on 2021/2/26 10:39
 */
public class Student implements Sequenceable {
    private int number;

    private String name;

    private Uri uri;


    public Student() {
    }

    public Student(int number, String name, Uri uri) {
        this.number = number;
        this.name = name;
        this.uri = uri;
    }

    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Uri getUri() {
        return uri;
    }

    public void setUri(Uri uri) {
        this.uri = uri;
    }

    //上面是传统的实体类的构造函数和getter、setter
    //下面是序列化的核心
    //向包裹中写入数据，包裹可以理解为一块内存区
    public boolean marshalling(Parcel out) {
        out.writeSequenceable(uri); //注意Uri类型的写法和普通数据类型有所不同
        return out.writeInt(number) && out.writeString(name);
    }

    //从包裹中读取数据
    public boolean unmarshalling(Parcel in) {
        this.number = in.readInt();
        this.name = in.readString();
        return in.readSequenceable(uri);    //注意Uri类型的写法和普通数据类型有所不同
    }

    //序列化对象的内部构造器，必须实现
    public static final Sequenceable.Producer
            PRODUCER = new Sequenceable.Producer
            () {
        public Student createFromParcel(Parcel in) {    //从包裹中获取数据构造对象
            // Initialize an instance first, then do customized unmarshlling.
            Student instance = new Student();
            instance.unmarshalling(in);
            return instance;
        }   //必须实现Producer
    };
}
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下面编写MainAbilitySlice的代码，给Text控件添加一个点击事件来跳转页面并且传递一个student参数

package com.xdw.sequencedemo.slice;

import com.xdw.sequencedemo.ResourceTable;
import com.xdw.sequencedemo.Student;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.components.Component;
import ohos.agp.components.Text;
import ohos.agp.window.dialog.ToastDialog;
import ohos.utils.net.Uri;

public class MainAbilitySlice extends AbilitySlice {
    private Text text;
    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_main);
        text = (Text)findComponentById(ResourceTable.Id_text_helloworld);
        text.setClickedListener(new Component.ClickedListener() {
            @Override
            public void onClick(Component component) {
                Intent intent1 = new Intent();
                Student student = new Student();
                student.setNumber(1);
                student.setName("夏德旺");
                Uri uri = Uri.parse("http://www.xiadewang.com:8080/login?username=xdw&password=123");
                String scheme = uri.getScheme();
                //new ToastDialog(getContext()).setText("scheme="+scheme).show();
                student.setUri(uri);
                intent1.setParam("student",student);
                present(new TestSlice(),intent1);
            }
        });
    }

    @Override
    public void onActive() {
        super.onActive();
    }

    @Override
    public void onForeground(Intent intent) {
        super.onForeground(intent);
    }
}
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编写TestSlice的代码接收传递过来的student参数，并且通过toast展示

package com.xdw.sequencedemo.slice;

import com.xdw.sequencedemo.ResourceTable;
import com.xdw.sequencedemo.Student;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.window.dialog.ToastDialog;
import ohos.utils.net.Uri;

/**
 * Created by 夏德旺 on 2021/2/26 10:39
 */
public class TestSlice  extends AbilitySlice {
    @Override
    protected void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_slice_test);
        if(intent!=null){
            Student student = intent.getSequenceableParam("student");
            String name = student.getName();
            Uri uri = student.getUri();
            //new ToastDialog(getContext()).setText("name="+name).show();
            new ToastDialog(getContext()).setText("scheme="+uri.getScheme()).show();
        }
    }

    @Override
    protected void onActive() {
        super.onActive();
    }

    @Override
    protected void onForeground(Intent intent) {
        super.onForeground(intent);
    }
}
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