AsyncTask任务优先级设置

在Android中，AsyncTask是一个用于执行后台任务的轻量级类

1. 自定义一个Executor：

import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

public class PriorityExecutor implements Executor {
    private static final int CORE_POOL_SIZE = 5;
    private static final int MAXIMUM_POOL_SIZE = 128;
    private static final int KEEP_ALIVE = 1;

    private final ThreadPoolExecutor threadPoolExecutor;

    public PriorityExecutor() {
        threadPoolExecutor = new ThreadPoolExecutor(
                CORE_POOL_SIZE,
                MAXIMUM_POOL_SIZE,
                KEEP_ALIVE,
                TimeUnit.SECONDS,
                new LinkedBlockingQueue<Runnable>());
    }

    @Override
    public void execute(final Runnable command) {
        if (command instanceof PriorityRunnable) {
            threadPoolExecutor.execute((PriorityRunnable) command);
        } else {
            threadPoolExecutor.execute(new PriorityRunnable(command, 0));
        }
    }
}

2. 创建一个实现Comparable接口的Runnable子类，用于设置任务优先级：

public class PriorityRunnable implements Runnable, Comparable<PriorityRunnable> {
    private final Runnable runnable;
    private final int priority;

    public PriorityRunnable(Runnable runnable, int priority) {
        this.runnable = runnable;
        this.priority = priority;
    }

    @Override
    public void run() {
        runnable.run();
    }

    @Override
    public int compareTo(PriorityRunnable another) {
        return Integer.compare(another.priority, this.priority);
    }
}

3. 使用自定义的PriorityExecutor执行AsyncTask：

PriorityExecutor priorityExecutor = new PriorityExecutor();

// 创建一个具有高优先级的任务
AsyncTask<Void, Void, Void> highPriorityTask = new AsyncTask<Void, Void, Void>() {
    // ...
};

// 创建一个具有低优先级的任务
AsyncTask<Void, Void, Void> lowPriorityTask = new AsyncTask<Void, Void, Void>() {
    // ...
};

// 使用自定义的PriorityExecutor执行任务
highPriorityTask.executeOnExecutor(priorityExecutor, (Void[]) null);
lowPriorityTask.executeOnExecutor(priorityExecutor, (Void[]) null);

通过这种方式，你可以为AsyncTask任务设置优先级。请注意，这种方法可能会影响应用程序的性能和响应时间，因此在使用时要谨慎。在大多数情况下，Android系统默认的线程池和任务调度策略已经足够满足需求。