延遲Java步驟執行

Question

我想知道是否有一種更簡單的方法來處理Java執行。

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

我想延遲功能的每一步，是否有更好的方法呢？

Answer 1

您可以使用類似的方法，但是我不是一個好主意。 我同意DaveHowes的觀點 ，沒有別的簡單方法可以做到這一點。

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

您可以將命令放入諸如List之類的數據結構中，並將該列表傳遞給執行該命令的方法，然后休眠一段時間。 也許更優雅一點，但肯定沒有更簡單。

您也可以考慮將它們添加到Timer中，但是，它再次更優雅，但是帶來了很多機器，而沒有在功能上進行很多改進。

Answer 3

您沒有說為什么要這樣做； 與在代碼中添加大量延遲相比，實現最終目標可能是更好的方法。

如果整個應用程序的大部分都需要這樣做，那么我將考慮在外部應用延遲機制：

• 如果這是為了調試，我將考慮使用JPDA的StepRequest類型。

• 在極少數情況下，您可能希望在生產代碼中使用ASM之類的東西來轉換目標字節代碼。

Answer 4

速度測試：

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);
    }
}

輸出：

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