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Android jetpack(Workmanager)篇

Android jetpack(Workmanager)篇

作者: 坑逼的严 | 来源:发表于2021-06-15 16:03 被阅读0次

    Workmanager是jetpack系列及其重要的一部分,他可以让用户设定定时任务,并设定一些条件,条件符合并到达时间后会自动执行,他的兼容性极高,在API23以上,它采用JobScheduler,以下采用AlarmManage和广播接受者。Workmanager他不是神,他也有延迟,他是系统提供出来的,很多app都能共享,所以同一时间的任务多,那么就会造成排队等候,就有了延迟。所以Workmanager适用于不急着使用的后台定时任务,如果像要下载文件等及时更新的,那么就还是service适合。

    使用

    设置Worker:

    public class MyWork extends Worker {
        public MyWork(@NonNull Context context, @NonNull WorkerParameters workerParams) {
            super(context, workerParams);
        }
    
        @NonNull
        @Override
        public Result doWork() {
            SystemClock.sleep(2000);
            Log.d("yanjin","doWork了!!!!");
            return Result.success();
        }
    }
    

    然后开始调用

    WorkManager workManager = WorkManager.getInstance(WorkerManagerActivity.this);
    workManager.enqueue(workRequest);
    

    那么就需要一个workRequest,这里我们设置一个一次性任务

    OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class)
                    .setConstraints(constraints)
                    .build();
    

    至此我们可以调用了,但是如果我们要加限制,那么就要额外添加如下代码:

    Constraints constraints = new Constraints.Builder()
                    .setRequiredNetworkType(NetworkType.NOT_REQUIRED)//设置网络情况
                    .setRequiresBatteryNotLow(true)//设置在电量不足的情况下不执行
                    .setRequiresCharging(true)//在充电时执行
                    .setRequiresStorageNotLow(true)//设置在容量不足的情况下不执行
    //                .setRequiresDeviceIdle(true)//在待机情况下执行,需要判断api大于23
                    .build();
    

    全部代码如下:

    public class WorkerManagerActivity extends AppCompatActivity {
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_worker_manager);
            findViewById(R.id.tv_one_time).setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    oneTime();
                }
            });
        }
    
        /**
         * 一次性任务
         */
        private void oneTime() {
            Constraints constraints = new Constraints.Builder()
                    .setRequiredNetworkType(NetworkType.NOT_REQUIRED)//设置网络情况
                    .setRequiresBatteryNotLow(true)//设置在电量不足的情况下不执行
                    .setRequiresCharging(true)//在充电时执行
                    .setRequiresStorageNotLow(true)//设置在容量不足的情况下不执行
    //                .setRequiresDeviceIdle(true)//在待机情况下执行,需要判断api大于23
                    .build();
            OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class)
                    .setConstraints(constraints)
                    .setInitialDelay(1000, TimeUnit.MILLISECONDS)//延时一秒
                    .build();
            WorkManager workManager = WorkManager.getInstance(WorkerManagerActivity.this);
            workManager.enqueue(workRequest);
        }
    }
    

    退避策略

    如果我们doWork里面返回的是Result.retry();那么我们很可能需要重试,比如我们上一次的任务因为没有网络导致没有执行,那么我们就要重试,并且我们还需要设置重试的时间间隔怎么办?那么就用到这个退避策略了。如下:

    OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class)
                    .setConstraints(constraints)
                    .setInitialDelay(1000, TimeUnit.MILLISECONDS)//延时一秒
                    .setBackoffCriteria(BackoffPolicy.LINEAR, Duration.ofSeconds(2))//线性增长,如果失败首先隔两秒再次请求,如果再次失败就是4秒
                    .build();
    

    BackoffPolicy还有EXPONENTIAL,指数型增长,可以自由试试。

    获取任务状态以及取消任务

    workManager.getWorkInfoByIdLiveData(workRequest.getId()).observe(this, new Observer<WorkInfo>() {
                @Override
                public void onChanged(WorkInfo workInfo) {
                    Log.d("yanjin","workInfo state = "+workInfo.getState());
                }
            });
    

    通过监听id就能获取到任务的状态,并且也可以取消任务。

    workManager.cancelWorkById(workInfo.getId());
    

    数据的传递

    workRequest中可以添加data数据源

    Data data = new Data.Builder()
                    .putString(KEY,"input")
                    .build();
            OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class)
                    .setConstraints(constraints)
                    .setInitialDelay(1000, TimeUnit.MILLISECONDS)//延时一秒
                    .setBackoffCriteria(BackoffPolicy.LINEAR, Duration.ofSeconds(2))//线性增长,如果失败首先隔两秒再次请求,如果再次失败就是4秒
                    .addTag(TAG)
                    .setInputData(data)
                    .build();
    

    在doWork中获取

    @NonNull
        @Override
        public Result doWork() {
            Data inputData = getInputData();
            String name = inputData.getString(WorkerManagerActivity.KEY);
            Log.d("yanjin","输出的数据 = "+name);
            SystemClock.sleep(2000);
    
            Data data = new Data.Builder()
                    .putString(WorkerManagerActivity.KEY,"input")
                    .build();
            return Result.success(data);
        }
    

    当然我们看到Result.success(data),同样我们也可以把处理的结果返回。在监听任务状态中获取

    workManager.getWorkInfoByIdLiveData(workRequest.getId()).observe(this, new Observer<WorkInfo>() {
                @Override
                public void onChanged(WorkInfo workInfo) {
                    if(workInfo != null && workInfo.getState() == WorkInfo.State.SUCCEEDED){
                        Data data = workInfo.getOutputData();
                        String name = data.getString(KEY);
                        Log.d("yanjin","传出的数据 = "+name);
                    }
    
                }
            });
    

    这样,一个轮回就完成了。

    周期性任务

    PeriodicWorkRequest是设置周期性执行任务的对象,大部分设置和OneTimeWorkRequest一样但是注意,他的最小周期是15分钟!!!

    任务链以及任务组合

    OneTimeWorkRequest workRequest1 = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            OneTimeWorkRequest workRequest2 = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            final WorkManager workManager = WorkManager.getInstance(WorkerManager2Activity.this);
            workManager.beginWith(workRequest1).then(workRequest2).enqueue();
    

    这是简单的任务链,先执行1再执行2。那么如果我们想要如下需求呢?


    image.png
    OneTimeWorkRequest workRequestA = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            OneTimeWorkRequest workRequestB = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            OneTimeWorkRequest workRequestC = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            OneTimeWorkRequest workRequestD = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            OneTimeWorkRequest workRequestE = new OneTimeWorkRequest.Builder(MyWork.class)
                    .build();
            WorkContinuation ABContinuation = WorkManager.getInstance(WorkerManager2Activity.this).beginWith(workRequestA).then(workRequestB);
            WorkContinuation CDContinuation = WorkManager.getInstance(WorkerManager2Activity.this).beginWith(workRequestC).then(workRequestD);
    //这里需要变成集合
            List<WorkContinuation> continuations = new ArrayList<>();
            continuations.add(ABContinuation);
            continuations.add(CDContinuation);
            WorkContinuation.combine(continuations).then(workRequestE).enqueue();
    

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