单次任务和周期任务的创建和执行，现在已经清楚了。但是有问题，之前创建的Worker就是一个单纯的Worker，和任务添加者是没有关系的，如果需要传递参数，应该怎么做？
WorkRequest.Builder.setInputData(Data)就是我们要找的东西。
Data
参数传递使用了一个叫Data的类
/**
* A persistable set of key/value pairs which are used as inputs and outputs for
* {@link ListenableWorker}s. Keys are Strings, and values can be Strings, primitive types, or
* their array variants.
* <p>
* This is a lightweight container, and should not be considered your data store. As such, there is
* an enforced {@link #MAX_DATA_BYTES} limit on the serialized (byte array) size of the payloads.
* This class will throw {@link IllegalStateException}s if you try to serialize or deserialize past
* this limit.
*/
public final class Data {
// .....
public static final class Builder {
// .....
}
}
Data是一个轻量级的键值对数据类，键为String，值可以是String、原始类型以及它们的数组。如果是其他类型，就会有异常。
从下面代码就能看出：
public @NonNull Builder put(@NonNull String key, @Nullable Object value) {
if (value == null) {
mValues.put(key, null);
} else {
Class<?> valueType = value.getClass();
if (valueType == Boolean.class
|| valueType == Byte.class
|| valueType == Integer.class
|| valueType == Long.class
|| valueType == Float.class
|| valueType == Double.class
|| valueType == String.class
|| valueType == Boolean[].class
|| valueType == Byte[].class
|| valueType == Integer[].class
|| valueType == Long[].class
|| valueType == Float[].class
|| valueType == Double[].class
|| valueType == String[].class) {
mValues.put(key, value);
} else if (valueType == boolean[].class) {
mValues.put(key, convertPrimitiveBooleanArray((boolean[]) value));
} else if (valueType == byte[].class) {
mValues.put(key, convertPrimitiveByteArray((byte[]) value));
} else if (valueType == int[].class) {
mValues.put(key, convertPrimitiveIntArray((int[]) value));
} else if (valueType == long[].class) {
mValues.put(key, convertPrimitiveLongArray((long[]) value));
} else if (valueType == float[].class) {
mValues.put(key, convertPrimitiveFloatArray((float[]) value));
} else if (valueType == double[].class) {
mValues.put(key, convertPrimitiveDoubleArray((double[]) value));
} else {
throw new IllegalArgumentException(
String.format("Key %s has invalid type %s", key, valueType));
}
}
return this;
}
而且传递的数据大小也有限制，最大为MAX_DATA_BYTES（10K）
参数传递
有了Data的知识，现在就传递一个名称给DelayWorker，作为一个描述字符串。
读取
DelayWorker新增一个名称参数，并在任务里面读取并打印出来
class DelayWorker(context: Context, workerParams: WorkerParameters) : Worker(context, workerParams) {
override fun doWork(): Result {
val name = inputData.getString(ARG_NAME) // 获取名称，并在日志里打印出来
Log.d(TAG, "[$name] doWork on ${Thread.currentThread().id} started - ${System.currentTimeMillis()} -> $id")
// emulated work
Thread.sleep(3000)
Log.d(TAG, "[$name] doWork on ${Thread.currentThread().id} ended - ${System.currentTimeMillis()}")
return Result.success()
}
companion object {
const val ARG_NAME = "name" // 名称参数
}
}
写入
如前文所说，写入参数当然使用Worker.Builder的方法：
val request = OneTimeWorkRequestBuilder<DelayWorker>()
.setInputData(
Data.Builder()
.putString(DelayWorker.ARG_NAME, "ONE-TIME")
.build()
)
.build()
执行结果：
2021-01-14 10:01:34.920 12531-12531/com.jacee.examples.workmanager D/JTest: enqueue on 2 1610589694920
2021-01-14 10:01:34.961 12531-12570/com.jacee.examples.workmanager D/JTest: [ONE-TIME] doWork on 7172 started - 1610589694961 -> 8aa7a2ee-af7f-47ad-9f17-b898268dd487
2021-01-14 10:01:34.962 12531-12531/com.jacee.examples.workmanager D/JTest: onetime: 8aa7a2ee-af7f-47ad-9f17-b898268dd487: ENQUEUED
2021-01-14 10:01:34.966 12531-12531/com.jacee.examples.workmanager D/JTest: onetime: 8aa7a2ee-af7f-47ad-9f17-b898268dd487: RUNNING
2021-01-14 10:01:37.965 12531-12570/com.jacee.examples.workmanager D/JTest: [ONE-TIME] doWork on 7172 ended - 1610589697965
2021-01-14 10:01:38.024 12531-12531/com.jacee.examples.workmanager D/JTest: onetime: 8aa7a2ee-af7f-47ad-9f17-b898268dd487: SUCCEEDED
成功实现名称传递。
小结
今天的内容很简单，但又很重要 —— 带参的任务，一定不会是个低概率需求。
