应用退至后台一小段时间后,应用进程会被挂起,无法执行对应的任务。如果应用在后台仍需要执行耗时不长的任务,如状态保存等,可以通过本文申请短时任务,扩展应用在后台的运行时间。
申请短时任务的按钮,不可连续点击超过3次,否则会超出短时任务数量限制并报错。使用过程中更多的约束与限制请参考短时任务(ArkTS)的约束与限制。
常用接口如下表所示,具体API说明详见transient_task_api.h。
封装函数
- #include "napi/native_api.h"
- #include "transient_task/transient_task_api.h"
-
- TransientTask_DelaySuspendInfo delaySuspendInfo;
- const int32_t TransientTask_TIMER = 3;
- static void Callback(void)
- {
- // 短时任务即将结束,业务在这里取消短时任务
- OH_BackgroundTaskManager_CancelSuspendDelay(delaySuspendInfo.requestId);
- }
-
- // 申请短时任务
- static napi_value RequestSuspendDelay(napi_env env, napi_callback_info info)
- {
- napi_value result;
- int32_t res = OH_BackgroundTaskManager_RequestSuspendDelay("test", Callback, &delaySuspendInfo);
- if (res == 0) {
- napi_create_int32(env, delaySuspendInfo.requestId, &result);
- } else {
- napi_create_int32(env, -1, &result);
- }
- return result;
- }
-
- // 获取剩余时间
- static napi_value GetRemainingDelayTime(napi_env env, napi_callback_info info)
- {
- napi_value result;
- int32_t delayTime = 0;
- int32_t res = OH_BackgroundTaskManager_GetRemainingDelayTime(delaySuspendInfo.requestId, &delayTime);
- if (res == 0) {
- napi_create_int32(env, delayTime, &result);
- } else {
- napi_create_int32(env, -1, &result);
- }
- return result;
- }
-
- // 取消短时任务
- static napi_value CancelSuspendDelay(napi_env env, napi_callback_info info)
- {
- napi_value result;
- int32_t res = OH_BackgroundTaskManager_CancelSuspendDelay(delaySuspendInfo.requestId);
- napi_create_int32(env, res, &result);
- return result;
- }
-
- // 获取所有短时任务信息
- TransientTask_TransientTaskInfo transientTaskInfo;
-
- static napi_value GetTransientTaskInfo(napi_env env, napi_callback_info info)
- {
- napi_value result;
- napi_create_object(env, &result);
- int32_t res = OH_BackgroundTaskManager_GetTransientTaskInfo(&transientTaskInfo);
- napi_value napiRemainingQuota = nullptr;
- // 获取成功,格式化数据并返回给接口
- if (res == 0) {
- napi_create_int32(env, transientTaskInfo.remainingQuota, &napiRemainingQuota);
- napi_set_named_property(env, result, "remainingQuota", napiRemainingQuota); // 格式化当日总配额
-
- napi_value info {nullptr};
- napi_create_array(env, &info);
- uint32_t count = 0;
- // 格式化所有已申请的短时任务信息
- for (int index = 0; index < TransientTask_TIMER; index++) {
- if (transientTaskInfo.transientTasks[index].requestId == 0) {
- continue;
- }
-
- napi_value napiWork = nullptr;
- napi_create_object(env, &napiWork);
-
- napi_value napiRequestId = nullptr;
- napi_create_int32(env, transientTaskInfo.transientTasks[index].requestId, &napiRequestId);
- napi_set_named_property(env, napiWork, "requestId", napiRequestId);
-
- napi_value napiActualDelayTime = nullptr;
- napi_create_int32(env, transientTaskInfo.transientTasks[index].actualDelayTime, &napiActualDelayTime);
- napi_set_named_property(env, napiWork, "actualDelayTime", napiActualDelayTime);
-
- napi_set_element(env, info, count, napiWork);
- count++;
- }
- napi_set_named_property(env, result, "transientTasks", info);
- } else {
- napi_create_int32(env, 0, &napiRemainingQuota);
- napi_set_named_property(env, result, "remainingQuota", napiRemainingQuota);
- napi_value info {nullptr};
- napi_create_array(env, &info);
- napi_set_named_property(env, result, "transientTasks", info);
- }
- return result;
- }
注册函数
- EXTERN_C_START
- static napi_value Init(napi_env env, napi_value exports)
- {
- napi_property_descriptor desc[] = {
- {"RequestSuspendDelay", nullptr, RequestSuspendDelay, nullptr, nullptr, nullptr, napi_default, nullptr},
- {"GetRemainingDelayTime", nullptr, GetRemainingDelayTime, nullptr, nullptr, nullptr, napi_default, nullptr},
- {"CancelSuspendDelay", nullptr, CancelSuspendDelay, nullptr, nullptr, nullptr, napi_default, nullptr},
- {"GetTransientTaskInfo", nullptr, GetTransientTaskInfo, nullptr, nullptr, nullptr, napi_default, nullptr },
- };
- napi_define_properties(env, exports, sizeof(desc) / sizeof(desc[0]), desc);
- return exports;
- }
- EXTERN_C_END
注册模块
- static napi_module demoModule = {
- .nm_version = 1,
- .nm_flags = 0,
- .nm_filename = nullptr,
- .nm_register_func = Init,
- .nm_modname = "entry",
- .nm_priv = ((void*)0),
- .reserved = { 0 },
- };
-
- extern "C" __attribute__((constructor)) void RegisterEntryModule(void)
- {
- napi_module_register(&demoModule);
- }
- import backgroundTaskManager from '@kit.BackgroundTasksKit';
-
- export const RequestSuspendDelay: () => number;
- export const GetRemainingDelayTime: () => number;
- export const CancelSuspendDelay: () => number;
- export const GetTransientTaskInfo: () => backgroundTaskManager.TransientTaskInfo;
- import testTransientTask from 'libentry.so';
-
- @Entry
- @Component
- struct Index {
- @State message: string = '';
- // ...
-
- build() {
- Row() {
- Column() {
- // ...
- Text(this.message)
- .fontSize(50)
- .fontWeight(FontWeight.Bold)
- Button() {
- Text("RequestSuspendDelay").fontSize(20)
- }
- .id('request_suspend_delay')
- .margin({ top: 10, bottom: 10 })
- .width(250)
- .height(40)
- .backgroundColor('#0D9FFB')
- .onClick(() => {
- this.RequestSuspendDelay();
- })
-
- Button(){
- Text('GetRemainingDelayTime').fontSize(20)
- }
- .id('get_remaining_delay_time')
- .margin({ top: 10, bottom: 10 })
- .width(250)
- .height(40)
- .backgroundColor('#0D9FFB')
- .onClick(() => {
- this.GetRemainingDelayTime();
- })
-
- Button(){
- Text('CancelSuspendDelay').fontSize(20)
- }
- .id('cancel_suspend_delay')
- .margin({ top: 10, bottom: 10 })
- .width(250)
- .height(40)
- .backgroundColor('#0D9FFB')
- .onClick(() => {
- this.CancelSuspendDelay();
- })
-
- Button(){
- Text('GetTransientTaskInfo').fontSize(20)
- }
- .id('get_transient_task_info')
- .margin({ top: 10, bottom: 10 })
- .width(250)
- .height(40)
- .backgroundColor('#0D9FFB')
- .onClick(() => {
- this.GetTransientTaskInfo();
- })
- }
- .width('100%')
- }
- .height('100%')
- }
-
- RequestSuspendDelay() {
- let requestId = testTransientTask.RequestSuspendDelay();
- // ...
- console.info('The returned requestId is ' + requestId);
- }
-
- GetRemainingDelayTime() {
- let time = testTransientTask.GetRemainingDelayTime();
- console.info('The time is ' + time);
- }
-
- CancelSuspendDelay() {
- let result = testTransientTask.CancelSuspendDelay();
- console.info('The return value is ' + result);
- }
-
- GetTransientTaskInfo() {
- let info = testTransientTask.GetTransientTaskInfo();
- console.info('The transientTaskInfo is ' + JSON.stringify(info));
- }
- }
配置CMakeLists.txt,本模块需要用到的共享库是libtransient_task.so,在工程自动生成的CMakeLists.txt中的target_link_libraries中添加此共享库。
- target_link_libraries(entry PUBLIC libace_napi.z.so libtransient_task.so)
连接设备并运行程序。
点击 申请短时任务 按钮,控制台会打印日志,示例如下:
- The returned requestId is 1
点击 获取剩余时间 按钮,控制台会打印日志,示例如下:
- The time is 18000
点击 取消短时任务 按钮,控制台会打印日志,示例如下:
- The return value is 0
点击 获取所有短时任务信息 按钮,控制台会打印日志,示例如下:
- The transientTaskInfo is {"remainingQuota":600000,"transientTasks":[]}
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