The role of the public_api.ts file in the Angular application

In Angular applications, public_api.tsit is a common convention to define the public API of a library or module. This file exports all parts of the library or module for external use, such as components, services, interfaces, types, functions, etc. When other apps or libraries reference this library, they can only access public_api.tsthe content exported in .

public_api.tsThe existence of has two main benefits:

1. Encapsulation : The internal implementation of the library can be changed freely, as long as public_api.tsthe content of the library remains unchanged, the application that references this library will not be affected. This also makes it easier for maintainers of the library to manage changes and iterations.

2. Simplified import : When using the library, you don't need to remember the files where each class and function is located, you only need to public_api.tsimport from. For example, you can import like this: import { MyComponent } from 'my-library';instead of importing like this: import { MyComponent } from 'my-library/lib/components/my-component/my-component';.

Here is an public_api.tsexample of a :

// 公共组件
export * from './lib/components/my-component';

// 公共服务
export * from './lib/services/my-service';

// 公共接口
export * from './lib/interfaces/my-interface';

// 公共类型
export * from './lib/types/my-type';

In this example, public_api.tsa component, a service, an interface and a type are exported. They are all libdefined in different files under the directory. Through public_api.ts, these can all be exported uniformly for use by other code.

In fact, public_api.tsit can be understood as the "facade" or "interface" of your library or module. It defines how your library interacts with the outside world, which functionality is exposed and which functionality is hidden. This design of separating internal implementation and external interface is a common pattern in software engineering and is called "Facade Pattern".

Summarize

public_api.tsAn important part of an Angular library or module responsible for managing and exporting public APIs. It provides a simple way to encapsulate and manage the internal implementation of the library, and at the same time, it is convenient for the users of the library to use the functions of the library.