AsyncTask任務(wù)優(yōu)先級(jí)設(shè)置

在A(yíng)ndroid中，AsyncTask是一個(gè)用于執(zhí)行后臺(tái)任務(wù)的輕量級(jí)類(lèi)

1. 自定義一個(gè)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. 創(chuàng)建一個(gè)實(shí)現(xiàn)Comparable接口的Runnable子類(lèi)，用于設(shè)置任務(wù)優(yōu)先級(jí)：

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. 使用自定義的PriorityExecutor執(zhí)行AsyncTask：

PriorityExecutor priorityExecutor = new PriorityExecutor();

// 創(chuàng)建一個(gè)具有高優(yōu)先級(jí)的任務(wù)
AsyncTask<Void, Void, Void> highPriorityTask = new AsyncTask<Void, Void, Void>() {
    // ...
};

// 創(chuàng)建一個(gè)具有低優(yōu)先級(jí)的任務(wù)
AsyncTask<Void, Void, Void> lowPriorityTask = new AsyncTask<Void, Void, Void>() {
    // ...
};

// 使用自定義的PriorityExecutor執(zhí)行任務(wù)
highPriorityTask.executeOnExecutor(priorityExecutor, (Void[]) null);
lowPriorityTask.executeOnExecutor(priorityExecutor, (Void[]) null);

通過(guò)這種方式，你可以為AsyncTask任務(wù)設(shè)置優(yōu)先級(jí)。請(qǐng)注意，這種方法可能會(huì)影響應(yīng)用程序的性能和響應(yīng)時(shí)間，因此在使用時(shí)要謹(jǐn)慎。在大多數(shù)情況下，Android系統(tǒng)默認(rèn)的線(xiàn)程池和任務(wù)調(diào)度策略已經(jīng)足夠滿(mǎn)足需求。