Question

我想知道是否有更简单的方法来延迟执行java。

function(){
  command 1;   
  thread.sleep();
  command 2;
  thread.sleep();
  ... and soo on
}

我想延迟我的功能中的每一步是否有更好的方法来做到这一点？

Answer 1

你可以使用这样的东西，但我不是个好主意。我同意 DaveHowes ，没有其他简单的方法可以做到这一点。

package main;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.List;

public class TempClass {
    public static void main(String[] args) throws ParseException, InterruptedException, InvocationTargetException, NoSuchMethodException, IllegalAccessException {
        new TempClass().function();
    }

    private void function() throws NoSuchMethodException, InterruptedException, InvocationTargetException, IllegalAccessException {
        final Class aClass = this.getClass();
        List<Method> methods = new ArrayList<Method>() {{
            add(aClass.getDeclaredMethod("command1"));
            add(aClass.getDeclaredMethod("command2"));
        }};
        for (Method method : methods) {
            method.setAccessible(true);
            method.invoke(this);
            Thread.sleep(1000);
        }
    }

    private void command1() {
        System.out.println("command1");
    }

    private void command2() {
        System.out.println("command2");
    }
}

Answer 2

您可以将命令放入数据结构（如List）中，并将列表传递给执行命令的方法，然后休眠一段时间。或许更优雅，但肯定不会更简单。

您也可以考虑将它们添加到计时器中，但同样，它更优雅，但却带来了相当多的机器而没有给您带来很多功能上的改进。

Answer 3

你没有说你为什么要这样做;可能有更好的方法来实现您的最终目标，而不是为您的代码添加一堆延迟。

如果在应用程序的大部分内容都需要这样做，我会考虑在外部应用延迟机制：

如果这是用于调试，我会考虑使用JPDA的StepRequest类型。
如果您希望在生产代码中使用此代码，我会使用类似ASM的内容转换目标字节代码。

Answer 4

速度测试：

package test;

import net.sf.cglib.reflect.FastClass;
import net.sf.cglib.reflect.FastMethod;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;

public class Test {

    private static final long SLEEP = 0;
    private static final Object[] withoutParameters = new Object[0];

    public static void main(String[] args) throws NoSuchMethodException, InvocationTargetException, InterruptedException, IllegalAccessException {
        final Method[] methods = getMethods(Test.class, "command1", "command2");
        final FastMethod[] fastMethods = getFastMethods(Test.class, methods);
        final Test test = new Test();
        final int loop = 10* 1000 * 1000;

        long timeStamp = System.currentTimeMillis();
        for (int i = 0; i < loop; i++) {
            test.functionDirectCall();
        }
        System.out.println("DirectCall time:" + (System.currentTimeMillis() - timeStamp));

        timeStamp = System.currentTimeMillis();
        for (int i = 0; i < loop; i++) {
            test.functionMethod(methods);
        }
        System.out.println("Method time:" + (System.currentTimeMillis() - timeStamp));

        timeStamp = System.currentTimeMillis();
        for (int i = 0; i < loop; i++) {
            test.functionFastMethod(fastMethods);
        }
        System.out.println("FastMethod time:" + (System.currentTimeMillis() - timeStamp));
    }

    private void functionDirectCall() throws InterruptedException {
        this.command1();
        Thread.sleep(SLEEP);
        this.command2();
        Thread.sleep(SLEEP);
    }

    private void functionMethod(Method... methods) throws InvocationTargetException, IllegalAccessException, InterruptedException {
        for (Method method : methods) {
            method.invoke(this);
            Thread.sleep(SLEEP);
        }
    }

    private void functionFastMethod(FastMethod... fastMethods) throws InvocationTargetException, InterruptedException {
        for (FastMethod fastMethod : fastMethods) {
            fastMethod.invoke(this, withoutParameters);
            Thread.sleep(SLEEP);
        }
    }

    private static Method[] getMethods(final Class aClass, final String... methodNames) throws NoSuchMethodException {
        return new ArrayList<Method>() {{
            for (String methodName : methodNames) {
                final Method method = aClass.getDeclaredMethod(methodName);
                method.setAccessible(true);
                this.add(method);
            }
        }}.toArray(new Method[methodNames.length]);
    }

    private static FastMethod[] getFastMethods(final Class aClass, final Method... methods) {
        final FastClass fastClass = FastClass.create(aClass);
        return new ArrayList<FastMethod>() {{
            for (Method method : methods) {
                add(fastClass.getMethod(method));
            }
        }}.toArray(new FastMethod[methods.length]);
    }

    public void command1() throws InterruptedException {
        Thread.sleep(SLEEP);
    }

    public void command2() throws InterruptedException {
        Thread.sleep(SLEEP);
    }
}

<强>输出：

DirectCall time:17615
Method time:19051
FastMethod time:17952

延迟Java步骤执行

4 个答案: