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Parcel简介
在IPC过程中，发送方可以使用Parcel提供的写方法，将待发送的数据以特定格式写入Parcel对象。接收方可以使用Parcel提供的读取方法从Parcel对象中读取特定格式的数据。
Parcel实例的默认容量为200KB。如果您想要更多或更少，请使用setCapacity(int)更改它。
注意：只有以下数据类型的数据才能写入或从包裹中读取： byte, byteArray, short, shortArray, int, intArray, long, longArray, float, floatArray, double, doubleArray, boolean, booleanArray, char, charArray, String, StringArray、 PlainBooleanArray, Serializable, Sequenceable, 和 SequenceableArray。
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方法介绍
2.1 addAppClassLoader(ClassLoader newClassLoader)public void addAppClassLoader（ClassLoader newClassLoader）添加第三方ClassLoader用于实例初始化。如果您需要封装或取消封装自定义序列化数据，请添加您自己的ClassLoader。
2.2 writeSequenceablepublic final void writeSequenceable(Sequenceable val)将可序列化对象写入Parcel实例。其余的方法参考文档Parcel资料
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封装Sequenceable实体类我们参考Sequenceable资料
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动手实践
今天将一个Sequenceable的集合存到Parcel然后读取出来
4.1 新建两个类 A类用户存放具体属性，B类用于存放A的实体类集合
A类代码如下public static class A implements Sequenceable { private int a; private int b; private int c; public A() { this(0, 0, 0); } public A(int a, int b, int c) { this.a = a; this.b = b; this.c = c; } @Override public boolean hasFileDescriptor() { return false; } @Override public boolean marshalling(Parcel out) { out.writeInt(a); out.writeInt(b); out.writeInt(c); return true; } @Override public boolean unmarshalling(Parcel in) { a = in.readInt(); b = in.readInt(); c = in.readInt(); return true; } public static final Sequenceable.Producer<A> PRODUCER = new Sequenceable.Producer<A>() { public A createFromParcel(Parcel in) { A instance = new A(); instance.unmarshalling(in); return instance; } }; @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; A a1 = (A) o; return a == a1.a && b == a1.b && c == a1.c; } @Override public int hashCode() { return Objects.hash(a, b, c); } @Override public String toString() { return "A{" + "a=" + a + ", b=" + b + ", c=" + c + '}'; }4.2 B类用于存放A的实体类集合，代码如下
public static class B implements Sequenceable { private List<A> list; private B() { } private B(List<A> list) { this.list = list; } @Override public boolean hasFileDescriptor() { return false; } @Override public boolean marshalling(Parcel out) { out.writeSequenceableList(list); return true; } @Override public boolean unmarshalling(Parcel in) { in.addAppClassLoader(getClass().getClassLoader()); list = in.readSequenceableList(A.class); return true; } public static final Sequenceable.Producer<B> PRODUCER = new Sequenceable.Producer<B>() { public B createFromParcel(Parcel in) { B instance = new B(); instance.unmarshalling(in); return instance; } }; @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; B b = (B) o; return Objects.equals(list, b.list); } @Override public int hashCode() { return Objects.hash(list); } }需要注意的是我们需要调用addAppClassLoader方法，这个地方比较容易出错，如下图
4.3新建abilitySlice ，然后在xml写一个控件用于存读Parcel中数据，xml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="$+id:bt1" ohos:height="100vp" ohos:background_element="#Ed6262" ohos:width="match_parent" ohos:text_alignment="center" ohos:text_size="30fp" ohos:text_color="#ffffff" ohos:text="存储数据"/> <Text ohos:top_margin="10vp" ohos:id="$+id:Result" ohos:height="100vp" ohos:multiple_lines="true" ohos:width="match_parent" ohos:text_alignment="center|left" ohos:text_size="20fp" ohos:text_color="#ed6262" /> </DirectionalLayout>4.4实现点击按钮事件，然后存读数据，代码如下
findComponentById(ResourceTable.Id_bt1).setClickedListener(new Component.ClickedListener() { @Override public void onClick(Component component) { List<A> list = new ArrayList<>(); A a = new A(1, 2, 3); A a2 = new A(2, 2, 3); A a3 = new A(3, 2, 3); list.add(a); list.add(a2); list.add(a3); B b = new B(list); Parcel parcel = Parcel.create(); parcel.writeSequenceable(b); B b1 = new B(); parcel.readSequenceable(b1); StringBuilder stringBuilder=new StringBuilder(); if (b1.list.size() > 0) { for (int i = 0; i < b1.list.size(); i++) { stringBuilder.append(" b1.list====>" + b1.list.get(i).toString()); stringBuilder.append("\n"); } } mResult.setText(stringBuilder.toString()); } }); -
运行效果
全部代码如下
5.1xml<DirectionalLayout xmlns:ohos="http://schemas.huawei.com/res/ohos" ohos:height="match_parent" ohos:width="match_parent" ohos:orientation="vertical"> <Text ohos:id="$+id:bt1" ohos:height="100vp" ohos:background_element="#Ed6262" ohos:width="match_parent" ohos:text_alignment="center" ohos:text_size="30fp" ohos:text_color="#ffffff" ohos:text="存储数据"/> <Text ohos:top_margin="10vp" ohos:id="$+id:Result" ohos:height="100vp" ohos:multiple_lines="true" ohos:width="match_parent" ohos:text_alignment="center|left" ohos:text_size="20fp" ohos:text_color="#ed6262" /> </DirectionalLayout>5.2 java 代码
package com.harmony.alliance.mydemo.slice; import com.harmony.alliance.mydemo.ResourceTable; import ohos.aafwk.ability.AbilitySlice; import ohos.aafwk.content.Intent; import ohos.agp.components.Component; import ohos.agp.components.Text; import ohos.utils.Parcel; import ohos.utils.Sequenceable; import java.util.*; public class ParcelTestSlice extends AbilitySlice { private Text mResult; @Override protected void onStart(Intent intent) { super.onStart(intent); setUIContent(ResourceTable.Layout_slice_main2); mResult= (Text) findComponentById(ResourceTable.Id_Result); findComponentById(ResourceTable.Id_bt1).setClickedListener(new Component.ClickedListener() { @Override public void onClick(Component component) { List<A> list = new ArrayList<>(); A a = new A(1, 2, 3); A a2 = new A(2, 2, 3); A a3 = new A(3, 2, 3); list.add(a); list.add(a2); list.add(a3); B b = new B(list); Parcel parcel = Parcel.create(); parcel.writeSequenceable(b); B b1 = new B(); parcel.readSequenceable(b1); StringBuilder stringBuilder=new StringBuilder(); if (b1.list.size() > 0) { for (int i = 0; i < b1.list.size(); i++) { stringBuilder.append(" b1.list====>" + b1.list.get(i).toString()); stringBuilder.append("\n"); } } mResult.setText(stringBuilder.toString()); } }); } public static class B implements Sequenceable { private List<A> list; private B() { } private B(List<A> list) { this.list = list; } @Override public boolean hasFileDescriptor() { return false; } @Override public boolean marshalling(Parcel out) { out.writeSequenceableList(list); return true; } @Override public boolean unmarshalling(Parcel in) { in.addAppClassLoader(getClass().getClassLoader()); list = in.readSequenceableList(A.class); return true; } public static final Sequenceable.Producer<B> PRODUCER = new Sequenceable.Producer<B>() { public B createFromParcel(Parcel in) { B instance = new B(); instance.unmarshalling(in); return instance; } }; @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; B b = (B) o; return Objects.equals(list, b.list); } @Override public int hashCode() { return Objects.hash(list); } } public static class A implements Sequenceable { private int a; private int b; private int c; public A() { this(0, 0, 0); } public A(int a, int b, int c) { this.a = a; this.b = b; this.c = c; } @Override public boolean hasFileDescriptor() { return false; } @Override public boolean marshalling(Parcel out) { out.writeInt(a); out.writeInt(b); out.writeInt(c); return true; } @Override public boolean unmarshalling(Parcel in) { a = in.readInt(); b = in.readInt(); c = in.readInt(); return true; } public static final Sequenceable.Producer<A> PRODUCER = new Sequenceable.Producer<A>() { public A createFromParcel(Parcel in) { A instance = new A(); instance.unmarshalling(in); return instance; } }; @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; A a1 = (A) o; return a == a1.a && b == a1.b && c == a1.c; } @Override public int hashCode() { return Objects.hash(a, b, c); } @Override public String toString() { return "A{" + "a=" + a + ", b=" + b + ", c=" + c + '}'; } } }5.3效果如下
{{o.name}}
{{m.name}}