harmony 鸿蒙@ohos.systemParameterEnhance (System Parameter)
@ohos.systemParameterEnhance (System Parameter)
The SystemParameter module provides system services with easy access to key-value pairs. You can use the APIs provided by this module to describe the service status and change the service behavior. The basic operation primitives are get and set. You can obtain the values of system parameters through getters and modify the values through setters.
For details about the system parameter design principles and definitions, see Parameter Management.
NOTE
- The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.
- The APIs provided by this module are system APIs.
- Third-party applications cannot use the APIs provided by this module, because system parameters each require specific discretionary access control (DAC) and mandatory access control (MAC) permissions.
Modules to Import
import systemparameter from '@ohos.systemParameterEnhance';
systemparameter.getSync
getSync(key: string, def?: string): string
Obtains the value of the system parameter with the specified key.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
def | string | No | Default value of the system parameter. It works only when the system parameter does not exist. The value can be undefined or any custom value. |
Return value
Type | Description |
---|---|
string | Value of the system parameter. If the specified key exists, the set value is returned. If the specified key does not exist and def is set to a valid value, the set value is returned. If the specified key does not exist and def is set to an invalid value (such as undefined) or is not set, an exception is thrown. |
Error codes
ID | Error Message |
---|---|
14700101 | if key is not found |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
try {
let info: string = systemparameter.getSync("const.ohos.apiversion");
console.log(JSON.stringify(info));
} catch(e) {
console.log("getSync unexpected error: " + e);
}
systemparameter.get
get(key: string, callback: AsyncCallback<string>): void
Obtains the value of the system parameter with the specified key.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
callback | AsyncCallback<string> | Yes | Callback used to return the result. |
Error codes
ID | Error Message |
---|---|
14700101 | if key is not found |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
systemparameter.get("const.ohos.apiversion", (err: BusinessError, data: string) => {
if (err == undefined) {
console.log("get test.parameter.key value success:" + data)
} else {
console.log(" get test.parameter.key value err:" + err.code)
}});
} catch(e) {
console.log("get unexpected error: " + e);
}
systemparameter.get
get(key: string, def: string, callback: AsyncCallback<string>): void
Obtains the value of the system parameter with the specified key. This API uses an asynchronous callback to return the result.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
def | string | Yes | Default value. |
callback | AsyncCallback<string> | Yes | Callback used to return the result. |
Error codes
ID | Error Message |
---|---|
14700101 | if key is not found |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
systemparameter.get("const.ohos.apiversion", "default", (err: BusinessError, data: string) => {
if (err == undefined) {
console.log("get test.parameter.key value success:" + data)
} else {
console.log(" get test.parameter.key value err:" + err.code)
}
});
} catch(e) {
console.log("get unexpected error:" + e)
}
systemparameter.get
get(key: string, def?: string): Promise<string>
Obtains the value of the system parameter with the specified key. This API uses a promise to return the result.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
def | string | No | Default value of the system parameter. It works only when the system parameter does not exist. The value can be undefined or any custom value. |
Return value
Type | Description |
---|---|
Promise<string> | Promise used to return the execution result. |
Error codes
ID | Error Message |
---|---|
14700101 | if key is not found |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
let p: Promise<string> = systemparameter.get("const.ohos.apiversion");
p.then((value: string) => {
console.log("get test.parameter.key success: " + value);
}).catch((err: BusinessError) => {
console.log("get test.parameter.key error: " + err.code);
});
} catch(e) {
console.log("get unexpected error: " + e);
}
systemparameter.setSync
setSync(key: string, value: string): void
Sets a value for the system parameter with the specified key.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
value | string | Yes | Value of the system parameter to set. |
Error codes
ID | Error Message |
---|---|
14700102 | if value is invalid |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
systemparameter.setSync("test.parameter.key", "default");
} catch(e) {
console.log("set unexpected error: " + e);
}
systemparameter.set
set(key: string, value: string, callback: AsyncCallback<void>): void
Sets a value for the system parameter with the specified key. This API uses an asynchronous callback to return the result.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
value | string | Yes | Value of the system parameter to set. |
callback | AsyncCallback<void> | Yes | Callback used to return the result. |
Error codes
ID | Error Message |
---|---|
14700102 | if value is invalid |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
systemparameter.set("test.parameter.key", "testValue", (err: BusinessError, data: void) => {
if (err == undefined) {
console.log("set test.parameter.key value success :" + data)
} else {
console.log("set test.parameter.key value err:" + err.code)
}});
} catch(e) {
console.log("set unexpected error: " + e);
}
systemparameter.set
set(key: string, value: string): Promise<void>
Sets a value for the system parameter with the specified key. This API uses a promise to return the result.
System capability: SystemCapability.Startup.SystemInfo
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
key | string | Yes | Key of the system parameter. |
value | string | Yes | Value of the system parameter to set. |
Return value
Type | Description |
---|---|
Promise<void> | Promise used to return the execution result. |
Error codes
ID | Error Message |
---|---|
14700102 | if value is invalid |
14700103 | if permission denied |
14700104 | if system internal error |
For details about the error codes, see System Parameter Error Codes.
Example
import { BusinessError } from '@ohos.base';
try {
let p: Promise<void> = systemparameter.set("test.parameter.key", "testValue");
p.then((value: void) => {
console.log("set test.parameter.key success: " + value);
}).catch((err: BusinessError) => {
console.log(" set test.parameter.key error: " + err.code);
});
} catch(e) {
console.log("set unexpected error: " + e);
}
你可能感兴趣的鸿蒙文章
harmony 鸿蒙System Common Events (To Be Deprecated Soon)
harmony 鸿蒙System Common Events
harmony 鸿蒙API Reference Document Description
harmony 鸿蒙Enterprise Device Management Overview (for System Applications Only)
harmony 鸿蒙BundleStatusCallback
harmony 鸿蒙@ohos.bundle.innerBundleManager (innerBundleManager)
harmony 鸿蒙@ohos.distributedBundle (Distributed Bundle Management)
harmony 鸿蒙@ohos.bundle (Bundle)
harmony 鸿蒙@ohos.enterprise.EnterpriseAdminExtensionAbility (EnterpriseAdminExtensionAbility)
- 所属分类: 后端技术
- 本文标签:
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
8、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦