HarmonyOS Exception Handling: A Comprehensive Guide
HarmonyOS Development: Global Exception Handling and Error Reporting
Developing robust applications requires a comprehensive strategy for handling exceptions. While debugging during development is straightforward, capturing and analyzing exceptions in testing or production environments presents a unique challenge. Third-party solutions like Bugly offer convenient exception reporting, but often come with costs. This article details how to implement global exception handling in HarmonyOS, providing a flexible solution that allows for customized error management and reporting strategies.
HarmonyOS Global Exception Handling
HarmonyOS simplifies global exception handling using the errorManager object. This object allows registering and unregistering error listeners, ideally within your main EntryAbility or AbilityStage. This approach provides a robust mechanism to capture unhandled exceptions and react accordingly, even in production scenarios.
Error Listener Functionality
| Interface Name | Description |
|---|---|
onUnhandledException(errMsg: string): void |
System callback invoked when an unhandled exception occurs. |
onException?(errObject: Error): void |
System callback invoked when an exception is reported to the JS layer. |
Here's a basic implementation:
errorManager.on('error', {
onUnhandledException: (errMsg) => {
console.log('Unhandled exception callback, onUnhandledException:', errMsg);
},
onException: (errorObj) => {
console.log('Exception reported to JS callback, onException:', errorObj);
}
});
This setup captures JS crashes; importantly, the app process does not terminate upon encountering an exception.
To unregister the error listener (recommended in the onDestroy lifecycle), you can use the following, where registerId is the ID returned by errorManager.on():
errorManager.off('error', registerId, (result) => {
// Handle the result of unregistering the listener
});
This provides a foundational mechanism. Further development could involve storing exception details locally, uploading them to a server, or implementing custom UI for viewing these errors.
Enhanced Exception Handling with a Custom Library
To streamline exception handling and reporting, a custom library can add features such as local error storage and a user-friendly UI for viewing exceptions. This library provides both global exception catching and a UI for viewing collected exceptions.
Library Features
Library Integration
Installation
Install the library using ohpm:
ohpm install @abner/catch
Alternatively, manually add it to your oh-package.json5:
{
"dependencies": {
"@abner/catch": "^1.0.3"
}
}
Initialization
Initialize within your AbilityStage or main UIAbility:
onHandledException({
context: this.context,
onExceptionBack: (exception) => {
// Handle exception reporting (e.g., to server or third-party)
}
});
Configuration Options:
| Property | Type | Description |
|---|---|---|
context |
Context |
Application context for database and storage access. |
isExceptionSave |
boolean |
Save exceptions locally (default: true). |
isFileSave |
boolean |
Save exceptions as files (default: database storage). |
faultType |
FaultLogger.FaultType |
Exception type (default: NO_SPECIFIC). Options include CPP_CRASH, JS_CRASH, APP_FREEZE. |
isExceptionIntercept |
boolean |
Intercept exceptions (default: true). If false, callbacks and saving are disabled. |
onExceptionBack |
callback function | Callback function for handling exception information. |
Closing Exception Handling
onExceptionDestroy();
Viewing Exceptions
openExceptionDialog();
This opens a dialog displaying a list of exceptions. Users can view details, delete individual entries, or clear the entire log.
Library Implementation Details
The library simplifies HarmonyOS's built-in exception handling. It handles local exception storage using either file system (fs module) or relational database (relationalStore module) storage. Further enhancements might include more sophisticated reporting mechanisms.
Repository: https://ohpm.openharmony.cn/#/cn/detail/@abner%2Fcatch
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