在鸿蒙Next开发中，ArkTS对自定义组件的成员变量使用的访问限定符private/public/protected有特定的校验规则，当不按规范使用时会产生相应的日志信息。
一、使用限制概述
（一）private修饰相关限制
- 对于@State/@Prop/@Provide/@BuilderParam/常规成员变量（不涉及更新的普通变量），使用private修饰时，在自定义组件构造时不允许进行赋值传参，否则会有编译告警日志提示。
（二）public修饰相关限制
- 对于@StorageLink/@StorageProp/@LocalStorageLink/@LocalStorageProp/@Consume变量，使用public修饰时，会有编译告警日志提示。
（三）private与特定装饰器同时修饰限制
- 对于@Link/@ObjectLink变量，使用private修饰时，会有编译告警日志提示。
（四）protected修饰限制
- 由于struct没有继承能力，所有上述变量使用protected修饰时，会有编译告警日志提示。
（五）@Require与private同时修饰限制
- 当@Require和private同时修饰自定义组件struct的@State/@Prop/@Provide/@BuilderParam/常规成员变量（不涉及更新的普通变量）时，会有编译告警日志提示。
二、错误使用场景示例
（一）private与@State/@Prop/@Provide/@BuilderParam同时修饰
- 代码示例
@Entry
@Component
struct AccessRestrictions {
@Builder
buildTest() {
Text("Parent builder")
}
build() {
Column() {
ComponentsChild({
state_value: "Hello",
prop_value: "Hello",
provide_value: "Hello",
builder_value: this.buildTest,
regular_value: "Hello"
})
}
.width('100%')
}
}
@Component
struct ComponentsChild {
@State private state_value: string = "Hello";
@Prop private prop_value: string = "Hello";
@Provide private provide_value: string = "Hello";
@BuilderParam private builder_value: () => void = this.buildTest;
private regular_value: string = "Hello";
@Builder
buildTest() {
Text("Child builder")
}
build() {
Column() {
Text("Hello")
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
}
}
-
编译告警日志
- Property'state_value' is private and can not be initialized through the component constructor.
- Property 'prop_value' is private and can not be initialized through the component constructor.
- Property 'provide_value' is private and can not be initialized through the component constructor.
- Property 'builder_value' is private and can not be initialized through the component constructor.
- Property'regular_value' is private and can not be initialized through the component constructor.
（二）public与@StorageLink/@StorageProp/@LocalStorageLink/@LocalStorageProp/@Consume同时修饰
- 代码示例
@Entry
@Component
struct AccessRestrictions {
@Provide consume_value: string = "Hello";
build() {
Column() {
ComponentChild()
}
.width('100%')
}
}
@Component
struct ComponentChild {
@LocalStorageProp("sessionLocalProp") public local_prop_value: string = "Hello";
@LocalStorageLink("sessionLocalLink") public local_link_value: string = "Hello";
@StorageProp("sessionProp") public storage_prop_value: string = "Hello";
@StorageLink("sessionLink") public storage_link_value: string = "Hello";
@Consume public consume_value: string;
build() {
Column() {
Text("Hello")
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
}
}
-
编译告警日志
- Property 'local_prop_value' can not be decorated with both @LocalStorageProp and public.
- Property 'local_link_value' can not be decorated with both @LocalStorageLink and public.
- Property'storage_prop_value' can not be decorated with both @StorageProp and public.
- Property'storage_link_value' can not be decorated with both @StorageLink and public.
- Property 'consume_value' can not be decorated with both @Consume and public.
（三）private与@Link/@ObjectLink同时修饰
- 代码示例
@Entry
@Component
struct AccessRestrictions {
@State link_value: string = "Hello";
@State objectLink_value: ComponentObj = new ComponentObj();
build() {
Column() {
ComponentChild({link_value: this.link_value, objectLink_value: this.objectLink_value})
}
.width('100%')
}
}
@Observed
class ComponentObj {
count: number = 0;
}
@Component
struct ComponentChild {
@Link private link_value: string;
@ObjectLink private objectLink_value: ComponentObj;
build() {
Column() {
Text("Hello")
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
}
}
-
编译告警日志
- Property 'link_value' can not be decorated with both @Link and private.
- Property 'objectLink_value' can not be decorated with both @ObjectLink and private.
（四）protected修饰
- 代码示例
@Entry
@Component
struct AccessRestrictions {
build() {
Column() {
ComponentChild({regular_value: "Hello"})
}
.width('100%')
}
}
@Component
struct ComponentChild {
protected regular_value: string = "Hello";
build() {
Column() {
Text("Hello")
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
}
}
-
编译告警日志
- The member attributes of a struct can not be protected.
（五）private、@Require与@State/@Prop/@Provide/@BuilderParam同时修饰
- 代码示例
@Entry
@Component
struct AccessRestrictions {
build() {
Column() {
ComponentChild({prop_value: "Hello"})
}
.width('100%')
}
}
@Component
struct ComponentChild {
@Require @Prop private prop_value: string = "Hello";
build() {
Column() {
Text("Hello")
.fontSize(50)
.fontWeight(FontWeight.Bold)
}
}
}
-
编译告警日志
- Property 'prop_value' can not be decorated with both @Require and private.
- Property 'prop_value' is private and can not be initialized through the component constructor.
开发者在使用鸿蒙Next自定义组件时，需遵循这些访问限定符的使用规则，避免因不规范使用而产生编译告警，确保组件的正确构建和功能实现。同时，注意这些规则从API version 12开始支持，在开发过程中要根据实际的API版本进行相应的处理。
