《編程之美》（Java實現） ：讓CPU佔用率畫直線和正弦曲線（Java實現）

1. public class CPUTest {  
2.       
3.     //定義時間片大小（毫秒）  
4.     public static final double TIME = 1000;  
5.     //畫直線方法  
6.     private static void lineGraph(double rate) throws InterruptedException{  
7.         while (true){  
8.             doSomeSimpleWork(rate * TIME);  
9.             Thread.sleep((long) (TIME - rate * TIME));  
10.         }  
11.     }  
12.     //畫正弦曲線方法  
13.     private static void sinGraph() throws InterruptedException{  
14.         double x = 0;  
15.         double y = 0;         
16.         while (true){  
17.             y = (Math.sin(x) + 1) * TIME / 2;  
18.             doSomeSimpleWork(y);  
19.             x += 0.1;  
20.             Thread.sleep((long) (TIME - y));  
21.         }  
22.     }  
23.     //佔用CPU方法  
24.     private static void doSomeSimpleWork(double time) {  
25.         long startTime = System.currentTimeMillis();  
26.         while ((System.currentTimeMillis() - startTime) < time) {  
27.         }  
28.     }  
29.       
30.     /** 
31.      * @param args the command line arguments 
32.      */  
33.     public static void main(String[] args) throws InterruptedException {  
34.         lineGraph(0.5);  
35.         sinGraph();  
36.     }  
37.       
38. }  

 

 

package cglib;

 

public class jiekou {

    public static void drawLine(){    
        int usage = 700;  
        System.out.println("Test Begins...");         
        while(true){          
            long start = System.currentTimeMillis();  
            while(System.currentTimeMillis() - start < usage );  
            try{  
                Thread.sleep(1000-usage);  
            }catch(Exception e){  
                System.out.print(e);  
            }         
        }  
    }  
    public static void drawSin(){  
        double x = Math.PI / 2;   
        while(true){  
            //下面這一句+1是由於sinx可能爲負數，最大爲-1,加上1的話就保證爲正了  
            //*0.5是應爲加1以後，最大數可能達到2，爲了限制在1之內，因此*0.5  
            long usage = (long)((Math.sin(x)+1)*0.5*1000);  
            System.out.println(usage);  
            long start =  System.currentTimeMillis();  
            while(System.currentTimeMillis() - start < usage);  
            try{  
                Thread.sleep(1000 - usage);  
            }catch(Exception e){  
                System.out.print(e);  
            }  
            x += 0.1;  
        }  
    }     
    public static void drawSinSpeedup(){  
        double x = Math.PI / 2;   
        //加入了刷新時間，能夠調控曲線彎曲程度  
        int flushtime = 5000;  
        while(true){  
            long usage = (long)((Math.sin(x)+1)*0.5*flushtime);  
            System.out.println(usage);  
            long start =  System.currentTimeMillis();  
            while(System.currentTimeMillis() - start < usage);  
            try{  
                Thread.sleep(flushtime - usage);  
            }catch(Exception e){  
                System.out.print(e);  
            }  
            x += 0.1;  
        }  
    }  
    
    public static void main(String[] args) throws InterruptedException {  
        drawLine();  
        drawSin();  
    }  

    }