application-dev/quick-start/har-package.md

# HAR
A Harmony Archive (HAR) is a static shared package that can contain code, C++ libraries, resource files, and configuration files (also called profiles). It enables modules and projects to share code of ArkUI components, resources, and more.

## When to Use
- As a second-party library for internal applications, by being released to an OHPM private repository.
- As a third-party library for external applications, by being released to the OHPM central repository.

## Constraints

- A HAR can only be referenced as a dependency of an application module. It cannot be installed or run independently on a device.
- No [UIAbility](../application-models/uiability-overview.md) or [ExtensionAbility](../application-models/extensionability-overview.md) can be declared in the configuration file of a HAR.
- The configuration file of a HAR does not support declaration of the [pages](./module-configuration-file.md#pages) tag. Still, it can include pages, which can be redirected through a [named route](../ui/arkts-routing.md#named-route).
- The HAR does not support referencing resources in the **AppScope** folder. This is because the content in the **AppScope** folder is not packaged into the HAR during building.
- A HAR can depend on other HARs, but does not support cyclic dependency or dependency transfer.

## Creating a HAR
You can create a HAR module in DevEco Studio.


## Developing a HAR

You can export the ArkUI components, APIs, and other resources of a HAR for other applications or intra-application modules to reference.

The **Index.ets** file acts as the entry of the HAR export declaration file and is where the HAR exports APIs. This file is automatically generated by DevEco Studio by default. You can specify another file as the entry declaration file in the **main** field in the **oh-package.json5** file of the module. The code snippet is as follows:
```json
{
  "main": "Index.ets"
}
```
### Exporting ArkUI Components
Use **export** to export the ArkUI components. The code snippet is as follows:
```ts
// library/src/main/ets/components/mainpage/MainPage.ets
@Component
export struct MainPage {
  @State message: string = 'HAR MainPage';

  build() {
    Column() {
      Row() {
        Text(this.message)
          .fontSize(32)
          .fontWeight(FontWeight.Bold)
      }
      .margin({ top: '32px' })
      .height(56)
      .width('624px')

      Flex({ justifyContent: FlexAlign.Center, alignItems: ItemAlign.Center, alignContent: FlexAlign.Center }) {
        Column() {
          Image($r('app.media.pic_empty')).width('33%')
          Text($r('app.string.empty'))
            .fontSize(14)
            .fontColor($r('app.color.text_color'))
        }
      }.width('100%')
      .height('90%')
    }
    .width('100%')
    .height('100%')
    .backgroundColor($r('app.color.page_background'))
  }
}
```
In the **Index.ets** file, declare the APIs that the HAR exposes to external systems. The code snippet is as follows:
```ts
// library/Index.ets
export { MainPage } from './src/main/ets/components/mainpage/MainPage';
```
### Exporting TS Classes and Methods
Use **export** to export TS classes and methods. Multiple TS classes and methods can be exported at the same time. The code snippet is as follows:
```ts
// library/src/main/ts/test.ets
export class Log {
    static info(msg: string) {
        console.info(msg);
    }
}

export function func() {
  return 'har func';
}

export function func2() {
  return 'har func2';
}
```
In the **Index.ets** file, declare the APIs that the HAR exposes to external systems. The code snippet is as follows:
```ts
// library/Index.ets
export { Log } from './src/main/ts/test';
export { func } from './src/main/ts/test';
export { func2 } from './src/main/ts/test';
```

### Exporting Native Methods
The HAR can contain .so files written in C++. Native methods in the .so file can be exported from the HAR in the following way. In the example, the **add** API in the **libnative.so** file is exported.
```ts
// library/src/main/ets/utils/nativeTest.ts
import native from 'liblibrary.so';

export function nativeAdd(a: number, b: number): number {
  let result: number = native.add(a, b);
  return result;
}
```
In the **Index.ets** file, declare the APIs that the HAR exposes to external systems. The code snippet is as follows:
```ts
// library/Index.ets
export { nativeAdd } from './src/main/ets/utils/nativeTest';
```

### Resources
Resources are packed into the HAR during building. Specifically, DevEco Studio collects resource files from the HAP module and its dependent modules, and overwrites the resource files with the same name (if any) based on the following priorities (in descending order):
- AppScope (only for the stage model of API version 9)
- Modules in the HAP
- Dependent HAR modules<br>If resource conflicts occur between dependent HAR modules, they are overwritten based on the dependency sequence indicated under **dependencies** in the **oh-package.json5** file. The module that is higher in the dependency sequence list has a higher priority. For example, in the following example, if **dayjs** and **lottie** folders contain files with the same name, resources in **dayjs** are used preferentially.
> **NOTE**
>
> With regard to resources in the internationalization folder of **AppScope**, HAP, and HAR directories, the preceding priority rules also apply to resources with the same internationalization qualifier. In addition, resources with internationalization qualifiers are prioritized over those in the **base** folder. For example, if resources with the same name are configured in both the **base** folder under **AppScope** and the **en_US** folder of a HAR, the one in the **en_US** folder is prioritized for internationalization purposes.
```
// oh-package.json5
{
  "dependencies": {
    "dayjs": "^1.10.4",
    "lottie": "^2.0.0"
  }
}
```

## Using a HAR

Using a HAR means referencing its ArkUI components, APIs, and resources.

To start with, configure dependency on the HAR.

### Referencing ArkUI Components

After configuring the dependency on the HAR, you can reference ArkUI components exported from the HAR by using **import**. The code snippet is as follows:
```ts
// entry/src/main/ets/pages/IndexSec.ets
import { MainPage } from 'library';

@Entry
@Component
struct IndexSec {
  build() {
    Row() {
      // Reference the ArkUI component in the HAR.
      MainPage()
    }
    .height('100%')
  }
}
```
### Referencing TS Classes and Methods
To reference the TS classes and methods exported from the HAR, use **import** as follows:
```ts
// entry/src/main/ets/pages/Index.ets
import { Log } from 'library';
import { func } from 'library';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Column() {
      Text(this.message)
        .fontFamily('HarmonyHeiTi')
        .fontWeight(FontWeight.Bold)
        .fontSize(32)
        .fontWeight(700)
        .fontColor($r('app.color.text_color'))
        .textAlign(TextAlign.Start)
        .margin({ top: '32px' })
        .width('624px')

      // Reference TS classes and methods.
      Button($r('app.string.button'))
        .id('button')
        .height(48)
        .width('624px')
        .margin({ top: '4%' })
        .type(ButtonType.Capsule)
        .fontFamily('HarmonyHeiTi')
        .borderRadius($r('sys.float.ohos_id_corner_radius_button'))
        .backgroundColor($r('app.color.button_background'))
        .fontColor($r('sys.color.ohos_id_color_foreground_contrary'))
        .fontSize($r('sys.float.ohos_id_text_size_button1'))
        .onClick(() => {
          // Reference TS classes and methods in the HAR.
          Log.info('har msg');
          this.message = 'func return: ' + func();
        })
    }
    .width('100%')
    .backgroundColor($r('app.color.page_background'))
    .height('100%')
  }
}
```

### Referencing Native Methods
To reference the native methods exported from the HAR, use **import** as follows:
```ts
// entry/src/main/ets/pages/Index.ets
import { nativeAdd } from 'library';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Column() {
      Text(this.message)
        .fontFamily('HarmonyHeiTi')
        .fontWeight(FontWeight.Bold)
        .fontSize(32)
        .fontWeight(700)
        .fontColor($r('app.color.text_color'))
        .textAlign(TextAlign.Start)
        .margin({ top: '32px' })
        .width('624px')

      // Reference the native method in the HAR.
      Button($r('app.string.native_add'))
        .id('nativeAdd')
        .height(48)
        .width('624px')
        .margin({ top: '4%', bottom: '6%' })
        .type(ButtonType.Capsule)
        .fontFamily('HarmonyHeiTi')
        .borderRadius($r('sys.float.ohos_id_corner_radius_button'))
        .backgroundColor($r('app.color.button_background'))
        .fontColor($r('sys.color.ohos_id_color_foreground_contrary'))
        .fontSize($r('sys.float.ohos_id_text_size_button1'))
        .onClick(() => {
          this.message = 'result: ' + nativeAdd(1, 2);
        })
    }
    .width('100%')
    .backgroundColor($r('app.color.page_background'))
    .height('100%')
  }
}
```

### Referencing Resources
Use **$r** to reference resources in the HAR. For example, add the **name: hello_har** string (defined in the **string.json** file) and **icon_har.png** image to the **src/main/resources** directory of the HAR module, and then reference the string and image in the entry module. The code snippet is as follows:
```ts
// entry/src/main/ets/pages/Index.ets
@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  build() {
    Column() {
      // Reference the string in the HAR.
      Text($r('app.string.hello_har'))
        .id('stringHar')
        .fontFamily('HarmonyHeiTi')
        .fontColor($r('app.color.text_color'))
        .fontSize(24)
        .fontWeight(500)
        .margin({ top: '40%' })

      List() {
        ListItem() {
          // Reference the image in the HAR.
          Image($r('app.media.icon_har'))
            .id('iconHar')
            .borderRadius('48px')
        }
        .margin({ top: '5%' })
        .width('312px')
      }
      .alignListItem(ListItemAlign.Center)
    }
    .width('100%')
    .backgroundColor($r('app.color.page_background'))
    .height('100%')
  }
}
```
## Building a HAR

As aforementioned, a HAR can be used as a second-party or third-party library for other applications.

To better protect your source code, enable obfuscation for the HAR so that DevEco Studio compiles, obfuscates, and compresses code during HAR building.

> **NOTE**
>
> Obfuscation is only available for ArkTS projects in the stage model.
> When obfuscation is enabled, the resource ID is **-1**, and APIs that obtain resources by ID, such as [ResourceManager](../reference/apis-localization-kit/js-apis-resource-manager.md), do not take effect.


Since API version 10, obfuscation is enabled by default, and can be set through the **enable** field under **ruleOptions** in the **build-profile.json5** file of the HAR. The configuration is as follows:

  ```json
  {
    "apiType": "stageMode",
    "buildOption": {
    },
    "buildOptionSet": [
      {
        "name": "release",
        "arkOptions": {
          "obfuscation": {
            "ruleOptions": {
              "enable": true,
              "files": [
                "./obfuscation-rules.txt"
              ]
            },
            "consumerFiles": [
              "./consumer-rules.txt"
            ]
          }
        }
      },
    ],
    "targets": [
      {
        "name": "default"
      }
    ]
  }
  ```

## Releasing a HAR

Follow the [instructions](https://developer.harmonyos.com/cn/docs/documentation/doc-guides-V3/creating_har_api9-0000001518082393-V3#section1213451811512) to release a HAR.