xcoding.commons.util

类 OptionalExecutorTask<Params,Progress,Result>

java.lang.Object

xcoding.commons.util.OptionalExecutorTask<Params,Progress,Result>

public abstract class OptionalExecutorTask<Params,Progress,Result>
extends java.lang.Object

### I delete this comments as it make the answer too long to submit ### 引入该类是为了辅助而不是替换AsyncTask，一般情况下的异步任务还是使用AsyncTask，但AsyncTask的线程池实现最多线程数只有5个， 这会导致不能使用AsyncTask运行长时间任务和多并发任务，该类为这两种情况提供了解决方案，长时间任务可以直接调用execute方法， 多并发任务可以调用executeOnExecutor方法来提供自己的线程池实现

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	OptionalExecutorTask.Status Indicates the current status of the task.

字段概要

字段

限定符和类型	字段和说明
static java.util.concurrent.Executor	THREAD_POOL_EXECUTOR An Executor that can be used to execute tasks in parallel.

构造器概要

构造器

构造器和说明
OptionalExecutorTask() Creates a new asynchronous task.

方法概要

限定符和类型	方法和说明
boolean	cancel(boolean mayInterruptIfRunning) Attempts to cancel execution of this task.
protected abstract Result	doInBackground(Params... params) Override this method to perform a computation on a background thread.
OptionalExecutorTask<Params,Progress,Result>	execute(Params... params) Executes the task with the specified parameters.
static void	execute(java.lang.Runnable runnable) Convenience version of execute(Object...) for use with a simple Runnable object.
OptionalExecutorTask<Params,Progress,Result>	executeOnExecutor(java.util.concurrent.Executor exec, Params... params) Executes the task with the specified parameters.
Result	get() Waits if necessary for the computation to complete, and then retrieves its result.
Result	get(long timeout, java.util.concurrent.TimeUnit unit) Waits if necessary for at most the given time for the computation to complete, and then retrieves its result.
OptionalExecutorTask.Status	getStatus() Returns the current status of this task.
static void	init()
boolean	isCancelled() Returns true if this task was cancelled before it completed normally.
protected void	onCancelled() Applications should preferably override onCancelled(Object).
protected void	onCancelled(Result result) Runs on the UI thread after cancel(boolean) is invoked and doInBackground(Object[]) has finished.
protected void	onPostExecute(Result result) Runs on the UI thread after doInBackground(Params...).
protected void	onPreExecute() Runs on the UI thread before doInBackground(Params...).
protected void	onProgressUpdate(Progress... values) Runs on the UI thread after publishProgress(Progress...) is invoked.
protected void	publishProgress(Progress... values) This method can be invoked from doInBackground(Params...) to publish updates on the UI thread while the background computation is still running.
static void	setDefaultExecutor(java.util.concurrent.Executor exec)

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

字段详细资料

THREAD_POOL_EXECUTOR

public static final java.util.concurrent.Executor THREAD_POOL_EXECUTOR

An Executor that can be used to execute tasks in parallel.

构造器详细资料

OptionalExecutorTask

public OptionalExecutorTask()

Creates a new asynchronous task. This constructor must be invoked on the UI thread.

方法详细资料

init

public static void init()

setDefaultExecutor

public static void setDefaultExecutor(java.util.concurrent.Executor exec)

getStatus

public final OptionalExecutorTask.Status getStatus()

Returns the current status of this task.

返回:

The current status.

doInBackground

protected abstract Result doInBackground(Params... params)

Override this method to perform a computation on a background thread. The specified parameters are the parameters passed to execute(Params...) by the caller of this task. This method can call publishProgress(Progress...) to publish updates on the UI thread.

参数:

params - The parameters of the task.

返回:

A result, defined by the subclass of this task.

另请参阅:

onPreExecute(), onPostExecute(Result), publishProgress(Progress...)

onPreExecute

protected void onPreExecute()

Runs on the UI thread before doInBackground(Params...).

另请参阅:

onPostExecute(Result), doInBackground(Params...)

onPostExecute

protected void onPostExecute(Result result)

Runs on the UI thread after doInBackground(Params...). The specified result is the value returned by doInBackground(Params...).

This method won't be invoked if the task was cancelled.

参数:

result - The result of the operation computed by doInBackground(Params...).

另请参阅:

onPreExecute(), doInBackground(Params...), onCancelled(Object)

onProgressUpdate

protected void onProgressUpdate(Progress... values)

Runs on the UI thread after publishProgress(Progress...) is invoked. The specified values are the values passed to publishProgress(Progress...).

参数:

values - The values indicating progress.

另请参阅:

publishProgress(Progress...), doInBackground(Params...)

onCancelled

protected void onCancelled(Result result)

Runs on the UI thread after cancel(boolean) is invoked and doInBackground(Object[]) has finished.

The default implementation simply invokes onCancelled() and ignores the result. If you write your own implementation, do not call super.onCancelled(result).

参数:

result - The result, if any, computed in doInBackground(Object[]), can be null

另请参阅:

cancel(boolean), isCancelled()

onCancelled

protected void onCancelled()

Applications should preferably override onCancelled(Object). This method is invoked by the default implementation of onCancelled(Object).

Runs on the UI thread after cancel(boolean) is invoked and doInBackground(Object[]) has finished.

另请参阅:

onCancelled(Object), cancel(boolean), isCancelled()

isCancelled

public final boolean isCancelled()

Returns true if this task was cancelled before it completed normally. If you are calling cancel(boolean) on the task, the value returned by this method should be checked periodically from doInBackground(Object[]) to end the task as soon as possible.

返回:

true if task was cancelled before it completed

另请参阅:

cancel(boolean)

cancel

public final boolean cancel(boolean mayInterruptIfRunning)

Attempts to cancel execution of this task. This attempt will fail if the task has already completed, already been cancelled, or could not be cancelled for some other reason. If successful, and this task has not started when cancel is called, this task should never run. If the task has already started, then the mayInterruptIfRunning parameter determines whether the thread executing this task should be interrupted in an attempt to stop the task.

Calling this method will result in onCancelled(Object) being invoked on the UI thread after doInBackground(Object[]) returns. Calling this method guarantees that onPostExecute(Object) is never invoked. After invoking this method, you should check the value returned by isCancelled() periodically from doInBackground(Object[]) to finish the task as early as possible.

参数:

mayInterruptIfRunning - true if the thread executing this task should be interrupted; otherwise, in-progress tasks are allowed to complete.

返回:

false if the task could not be cancelled, typically because it has already completed normally; true otherwise

另请参阅:

isCancelled(), onCancelled(Object)

get

public final Result get()
                 throws java.lang.InterruptedException,
                        java.util.concurrent.ExecutionException

Waits if necessary for the computation to complete, and then retrieves its result.

返回:

The computed result.

抛出:

java.util.concurrent.CancellationException - If the computation was cancelled.

java.util.concurrent.ExecutionException - If the computation threw an exception.

java.lang.InterruptedException - If the current thread was interrupted while waiting.

get

public final Result get(long timeout,
                        java.util.concurrent.TimeUnit unit)
                 throws java.lang.InterruptedException,
                        java.util.concurrent.ExecutionException,
                        java.util.concurrent.TimeoutException

Waits if necessary for at most the given time for the computation to complete, and then retrieves its result.

参数:

timeout - Time to wait before cancelling the operation.

unit - The time unit for the timeout.

返回:

The computed result.

抛出:

java.util.concurrent.CancellationException - If the computation was cancelled.

java.util.concurrent.ExecutionException - If the computation threw an exception.

java.lang.InterruptedException - If the current thread was interrupted while waiting.

TimeoutException - If the wait timed out.

java.util.concurrent.TimeoutException

execute

public final OptionalExecutorTask<Params,Progress,Result> execute(Params... params)

Executes the task with the specified parameters. The task returns itself (this) so that the caller can keep a reference to it.

Note: this function schedules the task on a queue for a single background thread or pool of threads depending on the platform version. When first introduced, AsyncTasks were executed serially on a single background thread. Starting with Build.VERSION_CODES.DONUT, this was changed to a pool of threads allowing multiple tasks to operate in parallel. After Build.VERSION_CODES.HONEYCOMB, it is planned to change this back to a single thread to avoid common application errors caused by parallel execution. If you truly want parallel execution, you can use the executeOnExecutor(java.util.concurrent.Executor, Params...) version of this method with THREAD_POOL_EXECUTOR; however, see commentary there for warnings on its use.

This method must be invoked on the UI thread.

参数:

params - The parameters of the task.

返回:

This instance of AsyncTask.

抛出:

java.lang.IllegalStateException - If getStatus() returns either AsyncTask.Status#RUNNING or AsyncTask.Status#FINISHED.

executeOnExecutor

public final OptionalExecutorTask<Params,Progress,Result> executeOnExecutor(java.util.concurrent.Executor exec,
                                                                            Params... params)

Executes the task with the specified parameters. The task returns itself (this) so that the caller can keep a reference to it.

This method is typically used with THREAD_POOL_EXECUTOR to allow multiple tasks to run in parallel on a pool of threads managed by AsyncTask, however you can also use your own Executor for custom behavior.

Warning: Allowing multiple tasks to run in parallel from a thread pool is generally not what one wants, because the order of their operation is not defined. For example, if these tasks are used to modify any state in common (such as writing a file due to a button click), there are no guarantees on the order of the modifications. Without careful work it is possible in rare cases for the newer version of the data to be over-written by an older one, leading to obscure data loss and stability issues. Such changes are best executed in serial; to guarantee such work is serialized regardless of platform version you can use this function with #SERIAL_EXECUTOR.

This method must be invoked on the UI thread.

参数:

exec - The executor to use. THREAD_POOL_EXECUTOR is available as a convenient process-wide thread pool for tasks that are loosely coupled.

params - The parameters of the task.

返回:

This instance of AsyncTask.

抛出:

java.lang.IllegalStateException - If getStatus() returns either AsyncTask.Status#RUNNING or AsyncTask.Status#FINISHED.

execute

public static void execute(java.lang.Runnable runnable)

Convenience version of execute(Object...) for use with a simple Runnable object.

publishProgress

protected final void publishProgress(Progress... values)

This method can be invoked from doInBackground(Params...) to publish updates on the UI thread while the background computation is still running. Each call to this method will trigger the execution of onProgressUpdate(Progress...) on the UI thread. onProgressUpdate(Progress...) will note be called if the task has been canceled.

参数:

values - The progress values to update the UI with.

另请参阅:

onProgressUpdate(Progress...), doInBackground(Params...)