Android体系架构：WorkManager

女爷i 2023-10-18 17:21 2阅读 0赞

WorkManager是Android自最新的支持包androidx引入的后台任务框架。和JobSchedule 相似，是JobSchedule 的改进。

WorkManager可实现：

一次性执行任务，链式执行任务，周期性执行任务，一定条件下（网络，电量）执行任务，设备重启后执行上次未完成任务等。

在Android studio中build.gradle引入WorkManager：

implementation "androidx.work:work-runtime:2.0.1"

因为Androidx和过去android的支持包不兼容，需要配置：

android.useAndroidX=true
    android.enableJetifier=true

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package zhangphil.app;
    
    import android.content.Context;
    import android.os.SystemClock;
    
    import androidx.annotation.NonNull;
    import androidx.work.Data;
    import androidx.work.Worker;
    import androidx.work.WorkerParameters;
    
    import java.text.SimpleDateFormat;
    import java.util.Date;
    
    
    public class MyWorker extends Worker {
        private SimpleDateFormat mSimpleDateFormat = new SimpleDateFormat("HH:mm:ss:SSS");
        private Date mDate = new Date();
    
        public MyWorker(@NonNull Context context, @NonNull WorkerParameters workerParams) {
            super(context, workerParams);
        }
    
        @NonNull
        @Override
        public Result doWork() {
            int n = getInputData().getInt(MainActivity.KEY, 1);
    
            System.out.println(n + "," + getId() + "开始任务doWork()");
    
            SystemClock.sleep(3000);
    
            mDate.setTime(System.currentTimeMillis());
            Data outputData = new Data.Builder()
                    .putString(MainActivity.KEY, n + "@" + mSimpleDateFormat.format(mDate) + "#" + getId())
                    .build();
    
            return Result.success(outputData);
        }
    
        @Override
        public void onStopped() {
            super.onStopped();
    
            System.out.println("任务onStop()");
        }
    }

package zhangphil.app;
    
    import android.os.Bundle;
    import android.widget.TextView;
    
    import androidx.appcompat.app.AppCompatActivity;
    import androidx.lifecycle.LiveData;
    import androidx.lifecycle.Observer;
    import androidx.work.Constraints;
    import androidx.work.Data;
    import androidx.work.NetworkType;
    import androidx.work.OneTimeWorkRequest;
    import androidx.work.Operation;
    import androidx.work.WorkInfo;
    import androidx.work.WorkManager;
    
    import java.util.List;
    import java.util.concurrent.TimeUnit;
    
    public class MainActivity extends AppCompatActivity {
    
        public static String KEY = "KEY";
        private String TAG = "tag";
        private TextView text;
        private String string = "";
        private static int VALUE = 1;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            text = findViewById(R.id.text);
    
            Data myData = new Data.Builder()
                    .putInt(KEY, VALUE++)
                    .build();
    
            //约束条件。
            Constraints constraints = new Constraints.Builder()
                    .setRequiresBatteryNotLow(true)
                    .setRequiredNetworkType(NetworkType.NOT_REQUIRED)
                    .build();
    
            OneTimeWorkRequest.Builder argsWorkBuilder = new OneTimeWorkRequest.Builder(MyWorker.class)
                    .setConstraints(constraints)
                    .setInitialDelay(1, TimeUnit.SECONDS)
                    .setInputData(myData);
    
            OneTimeWorkRequest request = argsWorkBuilder
                    .addTag(TAG)
                    .build();
    
            System.out.println(request.getId() + "进入onCreate()");
    
            LiveData<List<WorkInfo>> liveData = WorkManager.getInstance().getWorkInfosByTagLiveData(TAG);
    
            liveData.observe(this, new Observer<List<WorkInfo>>() {
                @Override
                public void onChanged(List<WorkInfo> workInfos) {
                    for (WorkInfo workInfo : workInfos) {
                        if (workInfo != null && workInfo.getState() == WorkInfo.State.SUCCEEDED) {
                            display(workInfo.getOutputData().getString(KEY));
                        }
                    }
                }
            });
    
            Operation operation = WorkManager.getInstance()
                    .enqueue(request);
    
            //取消任务。
            //WorkManager.getInstance().cancelWorkById(request.getId());
        }
    
        private void display(String s) {
            string = string + s + "\n";
            text.setText(string);
        }
    }

WorkManager可以执行链式任务，假设有下面的任务链：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly96aGFuZ3BoaWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1][]

那么可以这么写链式任务：

WorkContinuation chain1 = WorkManager.getInstance()
      .beginWith(workA)
      .then(workB);
    
    WorkContinuation chain2 = WorkManager.getInstance()
      .beginWith(workC)
      .then(workD);
    
    WorkContinuation chain3 = WorkContinuation
      .combine(chain1, chain2)
      .then(workE);
    chain3.enqueue();

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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly96aGFuZ3BoaWwuYmxvZy5jc2RuLm5ldA_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20190419145623609.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly96aGFuZ3BoaWwuYmxvZy5jc2RuLm5ldA==,size_16,color_FFFFFF,t_70